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Diseases & Conditions

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ACL injury

Learn about this injury that affects one of the main ligaments in your knee and most commonly occurs during sports such as soccer and football.

ARDS

Acute respiratory distress syndrome (ARDS) is sudden and serious lung failure that can occur in people who are critically ill or have major injuries.

Abdominal aortic aneurysm

An aneurysm in the lower part of the aorta can grow slowly and silently. Know the symptoms of this dangerous condition and how it is treated.

Absence seizure

This type of seizure produces unexpected symptoms, such as a vacant stare, lip smacking and eyelid fluttering.

Acanthosis nigricans

Acanthosis nigricans — Comprehensive overview covers causes, treatment of this skin condition.

Achalasia

In achalasia, the muscles in your throat don't relax, preventing the passage of food and drink. Learn more about this rare digestive disorder.

Achilles tendinitis

Achilles tendinitis — Comprehensive overview covers symptoms, causes, treatment of this overuse injury.

Achilles tendon rupture

An Achilles tendon rupture is an injury that is usually painful and likely to affect your ability to walk. Surgical repair is sometimes necessary.

Acne

Learn more about this common skin condition, including causes, treatments and simple skin care steps you can do at home to help control it.

Acoustic neuroma

Acoustic neuroma is a tumor that grows on the balance and hearing nerve in the head that may cause hearing loss.

Acromegaly

An excess of growth hormone causes the bones to keep growing, which can lead to a number of serious complications if left untreated.

Actinic keratosis

Find out more about this skin condition that causes a rough, scaly patch after years of ultraviolet exposure from the sun or indoor tanning.

Acute coronary syndrome

Acute coronary syndrome refers to many conditions that cause sudden, low blood flow to the heart. Know the symptoms, causes and treatment.

Acute flaccid myelitis (AFM)

Know the possible symptoms of acute flaccid myelitis (AFM), a rare but serious condition that affects young children.

Acute kidney failure

Learn what happens when the kidneys suddenly stop working, as well as what causes this condition and how it's treated.

Acute liver failure

Acute liver failure is a rapid loss of liver function, often in someone without liver problems. It's a medical emergency that requires urgent care.

Acute lymphocytic leukemia

Learn about this cancer that forms in the blood and bone marrow. Treatments include medications and bone marrow transplant.

Acute myelogenous leukemia

Learn about this cancer that forms in the bone and bone marrow. Treatments include medications and bone marrow transplant.

Acute sinusitis

Learn the latest treatment and prevention strategies for dealing with the stuffy nose and head pain that can come with this upper respiratory condition.

Addison's disease

Learn about this rare but serious disorder of the adrenal glands that's treated by replacing needed hormones.

Adenomyosis

Displaced endometrial tissue from adenomyosis can cause an enlarged uterus and painful, heavy periods.

Adjustment disorders

Adjustment disorders are stress-related conditions where you feel overwhelmed and have a hard time adjusting to a stressful event or change.

Adrenal cancer

Learn about this rare cancer that begins in the adrenal glands. Find out about symptoms, diagnosis and treatment, including adrenalectomy.

Adrenoleukodystrophy

Find out about diagnosis and treatment of adrenoleukodystrophy — a hereditary disorder that affects the brain, nervous system and adrenal gland.

Adult Still's disease

Adult Still's disease — Comprehensive overview covers symptoms, complications, treatment of this inflammatory disorder.

Adult attention-deficit/hyperactivity disorder (ADHD)

This mental health disorder includes a combination of persistent problems, such as difficulty paying attention, hyperactivity and impulsive behavior.

Age spots (liver spots)

Learn more about the harmless dark spots on your skin that tend to appear as you age, especially in areas exposed to the sun. Treatment is available.

Agoraphobia

Agoraphobia is an anxiety disorder in which you fear and avoid places or situations where you might feel panicked, trapped, helpless or embarrassed.

Airplane ear

That fullness in your ear when on an airplane that's climbing or descending results from uneven air pressure between your middle ear and the environment.

Albinism

In this group of inherited disorders, there is little or no production of melanin, a pigment that determines hair, skin and eye color and vision development.

Alcohol intolerance

Having an immediate reaction after drinking alcohol, such as a stuffy nose and skin flushing, might indicate alcohol intolerance.

Alcohol poisoning

Alcohol poisoning is a serious and sometimes deadly consequence of drinking large amounts of alcohol in a short time. Here's what to do in an emergency.

Alcohol use disorder

Unhealthy alcohol use ranges from mild to severe, including alcoholism and binge drinking, putting health and safety at risk. Early treatment is important.

Alcoholic hepatitis

Drinking heavily over years can cause inflammation of the liver. If you have alcoholic hepatitis, you must stop drinking.

Allergies

Allergy symptoms can range from mild to severe, even life-threatening. Most allergies can't be cured, but treatments can help.

Alpha-gal syndrome

An allergic reaction to meat-based meals had researchers stumped — until they connected the condition to bites from certain ticks.

Alzheimer's disease

Alzheimer's disease causes a progressive loss of brain cells that leads to memory loss and the decline of other thinking skills.

Ambiguous genitalia

Learn about causes and treatment of ambiguous genitalia, a rare disorder of sex development in which a baby's external genitals are not clearly male or female.

Ameloblastoma

Learn more about the symptoms and treatment of this rare, noncancerous (benign) tumor that develops in the jaw.

Amenorrhea

Absence of menstruation (amenorrhea) may be linked to an underlying, treatable problem. Learn about amenorrhea causes and when to seek help.

Amnesia

Read about the causes of memory loss, and steps you can take to get it back.

Amniotic fluid embolism

A rare, serious condition occurs when fetal cells or the fluid that surrounds a baby in the uterus during pregnancy enter the mother's bloodstream.

Ampullary cancer

Learn more about treatments for cancer of the ampulla of Vater, including the Whipple procedure and minimally invasive surgery.

Amyloidosis

This rare disease can affect different organs in different people. Find out how early and accurate diagnosis can lead to better outcomes.

Amyotrophic lateral sclerosis (ALS)

This progressive nervous system disease, also known as Lou Gehrig's disease, destroys nerve cells.

Anal cancer

Learn about this cancer that affects the anal canal and causes bleeding and pain. Treatment is usually with a combination of radiation and chemotherapy.

Anal fissure

Learn what causes a tear in the anus and how to prevent or treat this often painful condition.

Anal itching

Learn about the causes, treatment and self-care tips for this common, sometimes embarrassing condition.

Anaphylaxis

Anaphylaxis, a severe allergic reaction, is an emergency. Learn who's at risk, what to watch for and what to do when it occurs.

Anemia

Anemia — Comprehensive overview covers symptoms, causes, treatment of this red blood cell deficiency.

Angelman syndrome

Learn about this genetic disorder that causes developmental delays, problems with speech and other symptoms.

Angina

Learn about a type of chest pain caused by reduced blood flow to the heart. This symptom is a sign of underlying heart disease.

Angiosarcoma

Learn about this rare cancer that begins in the blood vessels and lymph vessels. Treatments include surgery, radiation therapy and chemotherapy.

Ankylosing spondylitis

Learn about this inflammatory disease that can cause some of the vertebrae in the spine to fuse over time.

Anorexia nervosa

Anorexia is an eating disorder characterized by an abnormally low body weight, intense fear of gaining weight and a distorted perception of body weight.

Anorgasmia in women

Anorgasmia is regular difficulty having an orgasm after plenty of sexual stimulation. It affects many women, causing distress.

Anterior vaginal prolapse (cystocele)

Anterior prolapse happens when the pelvic floor muscles weaken and the bladder pushes into the top front part of your vagina. Learn how it's treated.

Anthrax

Learn about the symptoms and risks of anthrax, a rare but deadly bacterial disease that's been used in bioterrorism.

Antibiotic-associated diarrhea

Learn more about why you might get diarrhea while taking antibiotics, as well as how to treat or prevent this uncomfortable and sometimes serious problem.

Antiphospholipid syndrome

Learn about causes and treatment of this blood disorder that mainly affects women and may cause blood clots and miscarriages.

Antisocial personality disorder

People with this mental condition consistently disregard right and wrong, antagonize and manipulate others, and ignore other's rights and feelings.

Anxiety disorders

Learn the symptoms of this mental health condition, and ways to manage worry and fear that interfere with your daily activities.

Aortic dissection

This life-threatening condition occurs when blood leaks through a tear in the body's main artery (aorta). Know the symptoms and how it's treated.

Aortic valve disease

Learn more about diseases that affect the valve between the heart's main pumping chamber and the body's main artery (aorta).

Aortic valve regurgitation

Learn more about the symptoms and treatment of this condition in which the heart's aortic valve doesn't close tightly.

Aortic valve stenosis

Learn more about the symptoms and treatment of this condition, which reduces or blocks blood flow from the heart to the body.

Aphasia

Some conditions, including stroke or head injury, can seriously affect a person's ability to communicate. Learn about this condition and its care.

Aplastic anemia

Your body stops producing enough new blood cells in this rare and serious condition, possibly causing fatigue, higher risk of infections and uncontrolled bleeding.

Appendicitis

Is it just a bellyache or something more serious? Find out about the signs, symptoms and treatment for appendicitis — an inflammation of the appendix.

Arteriosclerosis / atherosclerosis

Learn about the symptoms, causes and treatment for hardening of the arteries.

Arteriovenous fistula

Irregular connections between arteries and veins may cause certain complications. Learn more about the causes and possible treatment options.

Arteriovenous malformation

An AVM is a tangle of blood vessels that affects the flow of blood and oxygen. Treatment can help.

Arthritis

Learn about how different types of arthritis affect joints in different ways, along with how to get relief from arthritis pain.

Asbestosis

Exposure to asbestos fibers causes this chronic lung disease. It may be decades before signs and symptoms such as shortness of breath and coughing appear.

Ascariasis

Learn more about the causes, treatment and prevention of this roundworm infection.

Aspergillosis

This fungal lung infection is caused by inhaling certain mold spores. It may be serious in those with asthma or other chronic lung diseases.

Asthma

Find out what can trigger asthma and how to relieve your symptoms and breathe easier.

Asthma attack

Learn how to recognize when you need to step up treatment.

Astigmatism

Imperfect curvature of your eye can cause blurred distance and near vision. Learn about this common and treatable eye condition.

Astrocytoma

Learn about this type of cancer that can occur in the brain or spinal cord.

Ataxia

Often caused by an underlying condition, ataxia affects muscle control and coordination and impacts movement, speech and swallowing.

Atelectasis

Atelectasis is a partly or completely collapsed lung. Know the symptoms and causes.

Athlete's foot

Learn about the causes, symptoms, prevention and treatment of this common fungal skin infection.

Atopic dermatitis (eczema)

Learn more about the causes, symptoms and treatments of this itchy rash that most often begins before age 5 and persists.

Atrial fibrillation

A fast, pounding heartbeat could be due to A-fib, a type of heart rhythm problem (arrhythmia). Know the warning signs and when treatment is needed.

Atrial septal defect (ASD)

This opening between the heart's upper chambers is this common congenital heart defect, but can be treated.

Atrial tachycardia

This type of fast heartbeat may occur after heart surgery or during pregnancy. But infections may trigger it, too. Learn how it's diagnosed and treated.

Atrioventricular canal defect

This congenital heart defect, also called atrioventricular septal defect, involves a hole in the heart and abnormal heart valves. Learn how it's treated.

Atrioventricular nodal reentry tachycardia (AVNRT)

This most common type of supraventricular tachycardia, a type of irregular heartbeat, tends to occur in young women. Know the symptoms and treatment.

Attention-deficit/hyperactivity disorder (ADHD) in children

This condition affects children, and may continue into adulthood. It can include difficulty sustaining attention, hyperactivity and impulsive behavior.

Atypical depression

With this depression, you may brighten in response to positive events, eat and sleep too much, feel heaviness in your arms or legs, and feel rejected.

Atypical hyperplasia of the breast

Learn how a diagnosis of atypical lobular hyperplasia or atypical ductal hyperplasia affects your risk of breast cancer and what you can do.

Autism spectrum disorder

Autism spectrum disorder is a serious condition related to brain development that impairs the ability to communicate and interact with others.

Autoimmune hepatitis

This type of hepatitis occurs when your immune system attacks your liver with destructive antibodies. Immune-suppressing medication is the main treatment.

Autoimmune pancreatitis

Autoimmune pancreatitis is a relatively uncommon disease of the pancreas that may be mistaken for pancreatic cancer.

Autonomic neuropathy

Damage to the nerves that control involuntary body functions, such as blood pressure and digestion, results in autonomic neuropathy.

Avascular necrosis (osteonecrosis)

A broken bone or dislocated joint can block blood flow to the bone, causing bone tissue to die.

Baby acne

Baby acne — Comprehensive overview covers causes, symptoms, treatment of this newborn complexion problem.

Back pain

Back pain is one of the most common reasons people go to the doctor. Home treatment and proper body mechanics often will heal your back within a few weeks.

Bacterial vaginosis

Learn about symptoms, treatments and prevention of this common vaginal infection.

Bad breath

Bad breath — Comprehensive overview covers causes, treatment and prevention.

Bags under eyes

Learn about causes, treatments and home remedies — including cool compresses and not smoking — for bags under eyes, which become more common as you age.

Baker's cyst

Baker's cyst — Comprehensive overview covers symptoms, causes, treatment of this bulge behind the knee.

Balance problems

Learn about the causes and treatments of conditions that leave you feeling dizzy or unsteady.

Barrett's esophagus

Barrett's esophagus, which is linked to chronic heartburn, can turn into cancer of the esophagus. Learn about treatment.

Bartholin's cyst

A Bartholin's cyst is a fluid-filled lump near the vaginal opening. It's rarely serious, but when infected, it can be painful.

Basal cell carcinoma

Learn about symptoms, treatment and prevention of this common skin cancer that often occurs on the head and neck.

Bed-wetting

Bed-wetting — Learn about causes and treatments, including moisture alarms, bladder training and medications.

Bedbugs

Learn more about the symptoms, treatment, prevention of these parasitic insects and their bites.

Bedsores (pressure ulcers)

Learn about the symptoms, treatment and prevention of this common skin condition that often affects older adults with limited mobility.

Bee sting

Learn more about symptoms, treatment, self-care tips and prevention of bee stings, which in some people cause severe allergic reaction.

Behcet's disease

This rare disorder causes blood vessel inflammation throughout the body. Signs and symptoms depend on which parts of the body are affected.

Bell's palsy

Learn more about Bell's palsy, which causes temporary facial paralysis. Find out why Bell's palsy happens and what to do about it.

Benign paroxysmal positional vertigo (BPPV)

Learn more about the symptoms, causes and treatment of intense dizziness episodes.

Benign peripheral nerve tumor

Learn more about the different types of tumors that grow on or around the nerves that link to your brain and spinal cord.

Benign prostatic hyperplasia (BPH)

Benign prostatic hyperplasia — also known as an enlarged prostate — is a common, but treatable urinary condition in older men.

Bicuspid aortic valve

People with this present-at-birth (congenital) defect have an abnormal heart valve that can leak or become narrowed. Know how it's diagnosed and treated.

Bile reflux

This digestive problem tends to develop in people who've had stomach surgery and sometimes contributes to gastroesophageal reflux disease (GERD).

Binge-eating disorder

People with binge-eating disorder frequently consume unusually large amounts of food and feel unable to stop eating. Learn about symptoms and treatment.

Bipolar disorder

Bipolar disorder causes extreme mood swings that include emotional highs (mania or hypomania) and lows (depression).

Bird flu (avian influenza)

Do you still need to worry about the bird flu? Get the facts about symptoms, causes and prevention of this infectious disease.

Black hairy tongue

Black hairy tongue is a temporary, harmless oral condition that gives your tongue a dark, furry appearance.

Bladder cancer

Blood in the urine (hematuria) sometimes is a sign of bladder cancer. Learn about other bladder cancer signs and symptoms and explore treatment options.

Bladder exstrophy

This rare birth defect occurs when the bladder develops outside the fetus during pregnancy. The condition can be repaired with surgery.

Bladder stones

Minerals in your urine can crystallize if you have trouble emptying your bladder completely, creating this potentially painful condition.

Blastocystis hominis

This microscopic organism is a parasite that can live in your digestive system. Whether it causes digestive problems isn't clear.

Blepharitis

This often chronic eyelid condition can be difficult to treat. It might be uncomfortable, but it doesn't usually damage eyesight and isn't contagious.

Blocked tear duct

Watery, irritated eyes may occur when your tears can't drain normally. Learn about this common eye condition that affects newborns and sometimes, adults.

Blood in urine (hematuria)

Seeing blood in your urine can be alarming. Although the cause might be benign, it's important to see a doctor in case the cause is more serious.

Body dysmorphic disorder

This mental disorder causes persistent, intense focus, shame and anxiety over perceived body defects, often resulting in many cosmetic procedures as a fix.

Body lice

Body lice are tiny insects that live in your clothing and feed on your blood. Find out how to treat and prevent this itchy nuisance of a bug.

Boils and carbuncles

Learn about symptoms, causes, treatment and prevention of these painful pus-filled infections that cause bumps under your skin or leaking sores.

Bone cancer

Bone cancer most commonly affects the long bones in the arms and legs. Some varieties occur primarily in children, while others affect mostly adults.

Bone metastasis

Learn about the symptoms and causes of cancer that spreads to the bones. Find out about treatments, including medications, radiation and surgery.

Bone spurs

Joint damage due to osteoarthritis is the most common cause of bone spurs. Most bone spurs create no problems and don't need treatment.

Borderline personality disorder

This mental health disorder includes a pattern of unstable intense relationships, distorted self-image, extreme emotions and impulsiveness.

Botulism

This rare but serious condition can be caused by bacteria that have contaminated food or an injury. Learn more about how to prevent it.

Brachial plexus injury

Learn about these nerve injuries that usually result from auto or motorcycle accidents and which procedures can help restore arm function.

Bradycardia

Find out more about the symptoms, diagnosis and treatment of a slower than typical heartbeat.

Brain AVM (arteriovenous malformation)

Brain AVM (arteriovenous malformation) — Comprehensive overview covers causes, symptoms and treatments.

Brain aneurysm

Learn about the signs and symptoms that may occur when a thinning wall of a blood vessel in your brain bulges — and know when to get emergency care.

Brain metastases

Learn about symptoms, diagnosis and treatment of cancers that spread to the brain (secondary, or metastatic, brain tumors).

Brain tumor

Find out more about the different brain tumor types and treatments, including surgery, radiation therapy and chemotherapy.

Breast cancer

Learn about this common cancer, including information on prevention, symptoms, diagnosis and treatment.

Breast cysts

A firm, round lump in breast tissue could be a fluid-filled cyst. Typically not cancerous, breast cysts often need no treatment.

Breast pain

Learn about possible causes and treatments for breast pain, along with self-care remedies that may help keep you comfortable when breast pain flares.

Broken ankle

A simple misstep or twisting injury can cause bone fractures. Treatment depends on the exact site of injury and its severity.

Broken arm

Treatment depends on the site and severity of the injury. Simple breaks might be treated with a sling and ice. Complicated fractures may require surgery.

Broken collarbone

Broken collarbone — Comprehensive overview covers causes, symptoms and treatment of this common injury.

Broken foot

A severely broken foot may require surgery to implant plates, rods or screws into the broken bone to maintain proper position during healing.

Broken hand

You may be at higher risk of a broken hand if you participate in contact sports like football or hockey, or if you have a condition in which bones become thinner and more fragile (osteoporosis).

Broken heart syndrome

Learn more about this temporary heart muscle condition that can mimic a heart attack. It may be triggered by stressful events, such as a loved one's death.

Broken leg

Broken leg — Comprehensive overview covers symptoms, diagnosis and treatment of this type of fracture.

Broken nose

Broken nose — Comprehensive overview covers symptoms, causes and treatments of a nasal fracture.

Broken ribs

Broken ribs — Comprehensive overview covers symptoms, causes and treatment of rib bone fractures.

Broken toe

Pain when wearing shoes and difficulty walking can signal a broken toe — so see your doctor to help it heal and ease pain.

Broken wrist

The most common type of wrist fracture occurs when people try to catch themselves during a fall and land hard on an outstretched hand.

Bronchiolitis

Infection in the small airways (bronchioles) of the lungs is common in young kids and babies. Signs may include coughing, wheezing and labored breathing.

Bronchitis

Bronchitis is an inflammation of the tubes that carry air to and from the lungs. Coughing and shortness of breath are the major symptoms.

Brucellosis

Contact with raw dairy products is the most common cause of this serious infectious disease that spreads from animals to people.

Brugada syndrome

Learn about the symptoms, causes and treatments for this heart rhythm condition that is sometimes inherited.

Bruxism (teeth grinding)

Bruxism is a condition in which you grind, gnash or clench your teeth unconsciously when you're awake or while you're sleeping.

Buerger's disease

Read about this blood vessel disease that limits blood flow, especially to your hands and feet. Quitting smoking is the best treatment for this condition.

Bulimia nervosa

With bulimia, a serious eating disorder, you eat large amounts of food and then purge to get rid of extra calories. Learn about symptoms and treatment.

Bullous pemphigoid

Learn about the symptoms, treatment and self-care strategies for this blistery skin condition that affects older adults.

Bundle branch block

A delay or obstruction in the pathway that electrical impulses travel to make your heart beat can make it harder for your heart to pump blood.

Bunions

A bunion is a bony bump that forms on the joint at the base of your big toe. Learn more about the causes and treatments of this sometimes painful disorder.

Burning mouth syndrome

This chronic burning, without an obvious cause, may affect the tongue, gums, lips, cheeks, roof of your mouth or widespread areas of your mouth.

Burns

Understand how to prevent, treat and recover from burns ranging from minor to life-threatening.

Bursitis

Bursitis is the painful inflammation of small, fluid-filled sacs that cushion the bones, tendons and muscles near your joints. Ice can ease symptoms.

C. difficile infection

Learn more about this diarrhea-causing infection that often occurs after antibiotic use. Many, but not all, affected people are in health care facilities.

COPD

This chronic inflammatory lung disease causes obstructed airflow from the lungs, resulting in breathing difficulty, cough, mucus production and wheezing.

CSF leak (Cerebrospinal fluid leak)

Cerebrospinal fluid leaks may originate from the brain or spine, causing headaches, dizziness and other symptoms.

Calciphylaxis

Learn more about this uncommon condition that affects small blood vessels and skin tissues, causing painful skin ulcers.

Cancer

Find out the basics about cancer, including symptoms, causes and treatments. Learn steps you can take to prevent cancer.

Canker sore

Canker sore — Learn about the causes, treatment and prevention of this painful mouth sore.

Carbon monoxide poisoning

Carbon monoxide is colorless, odorless, tasteless — and extremely dangerous. Don't count on detecting it. Instead, prevent it.

Carcinoid syndrome

Find out about skin flushing and other symptoms of this syndrome caused by a rare cancer called a carcinoid tumor.

Carcinoid tumors

Learn about these slow-growing cancers that usually begin in the digestive system or in the lungs. Treatments include peptide receptor radionuclide therapy.

Carcinoma of unknown primary

In this uncommon and aggressive type of cancer, doctors aren't sure where the cancer began. Learn how they determine which treatments are most likely to help.

Cardiogenic shock

Most often the result of a severe heart attack, this rare condition can be deadly if not treated immediately.

Cardiomyopathy

This disease of the heart muscle makes it harder for the heart to pump blood to the rest of the body. Learn the different types and how they're treated.

Carotid artery disease

Learn about carotid artery disease symptoms, prevention and treatment options including stenting, angioplasty and carotid endarterectomy.

Carpal tunnel syndrome

Learn more about the symptoms, diagnosis and treatment of this common nerve disorder affecting the hand and arm.

Castleman disease

This rare disorder involves an overgrowth of cells in your body's lymph nodes. Treatment varies depending on how many lymph nodes are involved.

Cataracts

Are things starting to look fuzzy or blurry? Find out about symptoms, diagnosis and treatment for this common eye condition.

Cavernous malformations

Understand the signs and symptoms that may occur when blood vessels in the brain or spinal cord are tightly packed and contain slow-moving blood.

Cavities/tooth decay

Cavities, also called tooth decay, are permanently damaged areas in the hard surface of your teeth that develop into tiny openings or holes.

Celiac disease

In celiac disease, wheat protein (gluten) in food damages the small intestine, making it hard to absorb nutrients and causing a variety of symptoms.

Cellulite

Learn more about this common skin condition that causes dimpling of the thighs and buttocks. Treatment may result in temporary improvement.

Cellulitis

Find out more about this potentially serious skin infection and how a few simple skin care tips can help prevent it.

Central sleep apnea

Find out how a mix-up in brain signals can affect your breathing during sleep and learn how this breathing disorder can be treated.

Cerebral palsy

Damage to the developing brain, usually before birth, causes this disorder of movement, muscle tone or posture.

Cervical cancer

Screening with Pap tests can reduce the risk of this cancer that begins in the cervix. Learn more about symptoms, causes, prevention and treatment.

Cervical dystonia

This rare movement disorder causes neck muscles to contract involuntarily. This can make your head twist or turn into often painful positions.

Cervical spondylosis

As people age, the spinal disks in the neck shrink and bone spurs often develop. If symptoms occur, nonsurgical treatments are usually effective.

Cervicitis

Sexually transmitted infections are often the reason why a woman develops inflammation of the cervix, which can cause abnormal discharge and bleeding.

Chagas disease

Learn more about this inflammatory, infectious disease caused by a parasite and found in the feces of the triatomine bug.

Charcot-Marie-Tooth disease

Learn how to spot the symptoms and how doctors treat this group of peripheral nerve disorders.

Chemo brain

Learn about the memory and thinking changes that sometimes happen during and after cancer treatment. Find out about chemo brain treatments and ways to cope.

Chest pain

Chest pain has many possible causes — and some of them are serious. Here's why it's so important to see your health care provider about chest pain.

Chiari malformation

Find out about the symptoms, causes, and treatment of this brain disorder in which brain tissue extends into the spinal canal.

Chickenpox

Learn more about the symptoms, treatment and prevention of this once common childhood illness.

Chilblains

For some people, cold exposure means chilblains — itchy, red patches that can become sores. Find out how to treat and prevent this seasonal skin condition.

Child abuse

Child abuse includes physical, sexual, emotional and medical abuse, as well as neglect. Learn about signs, risk factors, how to get help and prevention.

Childhood apraxia of speech

Speech therapy can help children with this speech disorder that's caused by a problem with communication between the brain and the muscles used for speech.

Childhood asthma

The lungs and airways of children with asthma become inflamed, interfering with daily activities. Some children can have dangerous attacks.

Childhood obesity

Childhood obesity can lead to various conditions, including type 2 diabetes and high blood pressure. Learn how to protect your child's health.

Childhood schizophrenia

This severe mental disorder in children involves hallucinations, delusions, and disordered thinking and behavior that can impair the ability to function.

Chlamydia trachomatis

Chlamydia trachomatis is a common sexually transmitted infection (STI) that can lead to serious health problems if left untreated. Learn more about symptoms, treatment, prevention.

Cholangiocarcinoma (bile duct cancer)

Learn about symptoms, risk factors, diagnosis and treatment, including transplant, for this rare cancer that affects the bile ducts of older adults.

Cholecystitis

Cholecystitis is gallbladder inflammation. Learn the causes, symptoms, complications and treatment.

Cholera

Cholera is a treatable — yet potentially fatal — bacterial disease that causes diarrhea and dehydration. Learn how to lower your risk.

Cholestasis of pregnancy

Cholestasis of pregnancy makes an expectant mom very itchy, and it can be dangerous for her baby. Know the causes and treatment.

Chondrosarcoma

Learn about this rare type of cancer that primarily affects bone, particularly in the shoulders, hips and pelvis. Treatment usually involves surgery.

Chordoma

Find out about this rare type of bone cancer. Learn about innovative chordoma treatments, including minimally invasive surgery and proton therapy.

Choroid plexus carcinoma

This rare type of cancerous brain tumor occurs mainly in children under 2. Treatment usually involves surgery and radiation therapy.

Chronic cough

A cough that lasts for weeks could be caused by smoking, postnasal drip, asthma, acid reflux, respiratory infections, COPD or another underlying problem.

Chronic daily headaches

If you have a headache most days, you might have one of the most disabling headache conditions, chronic daily headaches. Aggressive treatment and long-term management might help.

Chronic exertional compartment syndrome

Learn about this condition that causes pain and swelling in muscles of the legs or arms during exercise.

Chronic fatigue syndrome

This complicated disorder may be triggered by an infection. While there's no cure for chronic fatigue syndrome, treatment focuses on improving symptoms.

Chronic granulomatous disease

Learn about this inherited disease usually diagnosed in childhood that makes it difficult for your body to fight infections.

Chronic hives

Learn how this long-lasting skin condition that causes itchy welts is diagnosed and what treatments work best.

Chronic kidney disease

Learn about kidney failure symptoms, tests, diagnosis and treatment options, including medication, dialysis and kidney transplant.

Chronic lymphocytic leukemia

Learn about this cancer that forms in white blood cells called lymphocytes. Treatments include chemotherapy, targeted therapy and immunotherapy.

Chronic myelogenous leukemia

Learn about chronic myelogenous leukemia (CML) symptoms and causes. Find out how doctors treat CML, including targeted therapy and bone marrow transplant.

Chronic pelvic pain in women

Chronic pelvic pain can be a symptom of another disease or a condition in its own right. Learn how this painful condition is diagnosed and treated.

Chronic sinusitis

Read more about possible causes of lasting sinus troubles, what treatments are available and how you can prevent this problem in the future.

Chronic traumatic encephalopathy

This type of brain degeneration is likely caused by recurrent concussions, but what causes the damage isn't well understood.

Churg-Strauss syndrome

This rare blood vessel disease may cause breathing trouble, face pain and a persistent runny nose. Medications can help.

Cirrhosis

Cirrhosis is an advanced stage of scarring and damage of the liver. Find out about symptoms and treatment of this life-threatening liver condition.

Claudication

Too little blood flow to the legs and arms can cause pain, especially during exercise. Learn more about diagnosing and treating intermittent claudication.

Cleft lip and cleft palate

Surgery can fix openings or splits in the upper lip, or the roof of the mouth (palate), or both types of these birth defects.

Clubfoot

This term describes a range of congenital foot abnormalities in which the foot is twisted out of shape or position, keeping it from moving up and down.

Cluster headache

These painful headaches cause severe pain on one side of the head and tend to occur in frequent bouts called cluster periods.

Coarctation of the aorta

Learn more about the causes and treatment of this usually congenital heart condition that is treatable but requires lifelong follow-up.

Cold sore

Learn more about the causes, symptoms, treatment and prevention of this common lip sore caused by the herpes simplex virus type 1 (HSV-1).

Cold urticaria

Learn more about the symptoms and treatment of this allergic skin reaction caused by cold that most often affects young adults.

Colic

Consoling a baby who cries a lot for no apparent reason is a challenge. Learn strategies for caring for your infant and coping with the stress.

Colon cancer

Find out about symptoms and risk factors for colon cancer, also called colorectal cancer. Learn about treatment options, including minimally invasive surgery.

Colon polyps

Have you had your colonoscopy? Colon polyps typically don't cause symptoms, so it's important to have regular screenings.

Color blindness

Is it red or is it green? Learn more about what causes color blindness and how to tell whether or not you can distinguish between certain shades of color.

Coma

Coma is a state of prolonged unconsciousness with many possible causes. While it rarely lasts longer than a few weeks, some people never wake from a coma.

Common cold

A viral infection of your nose and throat can include signs and symptoms such as a stuffy nose, sore throat, cough and low-grade fever.

Common cold in babies

This viral infection causes a runny nose and nasal congestion in babies. Find out how to ease symptoms and when to see a doctor.

Common warts

Find out tips for preventing and dealing with this common skin condition that causes small, rough growths on your fingers and hands.

Complex regional pain syndrome

Learn about this neurological condition that may affect an arm or a leg after an injury or surgery. Early treatment may prevent a recurrence.

Complicated grief

In complicated grief, painful emotions of loss don't improve with time and are so severe that you have trouble recovering and resuming your own life.

Compulsive gambling

Compulsive gambling is an addictive disorder — the uncontrollable urge to keep gambling despite the toll it takes on your life.

Compulsive sexual behavior

Compulsive sexual behavior or hypersexuality is an excessive preoccupation with sexual fantasies, urges or behaviors that disrupts your life or is harmful to you or others.

Concussion

This brain injury causes symptoms such as headaches, dizziness and difficulty concentrating that usually improve within days to weeks.

Congenital adrenal hyperplasia

Congenital adrenal hyperplasia (CAH) is a group of inherited genetic conditions that limits the adrenal glands' ability to make certain vital hormones.

Congenital heart defects in children

Learn about symptoms, tests and treatments for children born with a problem in the structure of the heart (congenital heart defect).

Congenital heart disease in adults

A heart problem present at birth may not cause symptoms until adulthood. Learn how adult congenital heart disease is treated and what complications may occur.

Congenital mitral valve anomalies

Learn how these congenital heart defects can cause your mitral valve to leak or become narrowed.

Conjoined twins

If an early embryo only partially separates and two fetuses develop, they remain physically connected — most often at the chest, abdomen or pelvis.

Constipation

Chronically constipated? Find out what could be the cause and learn how to prevent and treat infrequent bowel movements.

Constipation in children

Learn what could cause constipation in your child, what you can do to prevent it and treatments that will get the bowel moving again.

Contact dermatitis

Contact with certain substances, such as poison ivy, skin lotions and detergents, can cause a red, itchy rash. Here's how to manage this common form of dermatitis.

Convergence insufficiency

Convergence insufficiency typically causes one eye to drift outward when you're trying to focus, making it hard to concentrate and tiring your eyes.

Corns and calluses

Find out more about these hardened areas of skin that often affect the feet and fingers. Try these self-care tips to make corns and calluses disappear.

Coronary artery disease

Learn about this serious heart condition in which the major blood vessels that supply your heart with blood become damaged or diseased.

Coronavirus disease 2019 (COVID-19)

Find out about coronavirus disease 2019 (COVID-19) and the coronavirus that causes it (SARS-CoV-2). Learn about symptoms, risks and ways to protect yourself.

Corticobasal degeneration (corticobasal syndrome)

Learn about this rare condition that affects your nerve cells and may cause difficulties in speech, movement and thinking.

Costochondritis

This chest wall pain, caused by inflammation, usually improves on its own.

Cough headaches

Often triggered by coughing and other types of straining, these headaches can be harmless or signal another problem in the brain.

Cradle cap

Learn about the symptoms, treatments and home care tips for this short-lived type of seborrheic dermatitis that's common in infants.

Craniopharyngioma

Learn more about this noncancerous tumor that forms near the brain's pituitary gland, including diagnosis and treatment options.

Craniosynostosis

This condition results in premature fusing of one or more of the joints between the bone plates of an infant's skull before the brain is fully formed.

Creutzfeldt-Jakob disease

Learn more about the definition, symptoms, causes and diagnosis of this degenerative brain disorder that leads to dementia.

Crohn's disease

Crohn's disease can cause stomach pain, severe diarrhea and weight loss. Learn about symptoms and treatment for this debilitating, but treatable, digestive condition.

Croup

This upper airway infection obstructs breathing and causes a barking cough. It involves swelling around the voice box, windpipe and bronchial tubes.

Cryoglobulinemia

When abnormal proteins in your blood clump together at temperatures below 98.6 F (37 C), it can block blood flow and damage your skin, joints and nerves.

Cushing syndrome

High levels of the hormone cortisol in your body cause this endocrine disorder. Learn about symptoms, causes and treatment.

Cutaneous B-cell lymphoma

Learn about this type of cancer that starts in the white blood cells and affects the skin. Treatment options include surgery, radiation and chemotherapy.

Cutaneous T-cell lymphoma

Learn about this type of non-Hodgkin's lymphoma that attacks the skin. Find out about cutaneous T-cell lymphoma (CTCL) symptoms, diagnosis and treatments.

Cyclic vomiting syndrome

Cyclic vomiting syndrome often starts in childhood and is marked by spells of vomiting several times an hour over a period of hours or days.

Cyclospora infection

Learn more about the symptoms, causes, treatment of this foodborne intestinal illness that causes watery, sometimes explosive, diarrhea.

Cyclothymia (cyclothymic disorder)

Also called cyclothymic disorder, this mood disorder causes emotional ups and downs that are less extreme than bipolar disorder. Learn about treatment.

Cystic fibrosis

This inherited condition causes severe damage to the lungs, digestive system and other organs. Learn about improvements in screening and treatments.

Cystitis

Cystitis is an inflammation of the urinary bladder. It's most often caused by a bacterial infection but may have other causes.

Cytomegalovirus (CMV) infection

Understand the symptoms and treatment of this common viral infection that can cause health problems for babies and people who have weakened immunity.

Dandruff

Learn about the causes of this sometimes embarrassing, flaky scalp disorder and which medicated shampoos and self-care habits may help control it.

De Quervain's tenosynovitis

De Quervain's tenosynovitis — Comprehensive overview of symptoms, treatment of this painful wrist condition.

Deep vein thrombosis (DVT)

You can develop this potentially serious condition, with few or no symptoms. It's good to know the risk factors.

Dehydration

Dehydration is especially common and dangerous for infants, young children and older adults. Learn more about treating and preventing dehydration.

Delayed ejaculation

Learn what could be causing delayed or absent ejaculation and how it can be treated.

Delayed sleep phase

Learn more about this sleep condition that causes a delay in usual sleep patterns.

Delirium

This serious disturbance in mental abilities develops fast and results in confused thinking and reduced awareness of surroundings. Symptoms and causes vary.

Dementia

This group of symptoms with many causes affects memory, thinking and social abilities. Some symptoms may be reversible.

Dengue fever

Learn how to identify the symptoms of this serious, mosquito-borne infection and how to protect yourself from infection.

Depersonalization-derealization disorder

Depersonalization-derealization disorder is when you feel that you're observing yourself from outside your body or that things around you aren't real.

Depression (major depressive disorder)

Depression is a mood disorder that causes a persistent feeling of sadness and loss of interest and can interfere with your daily functioning.

Dermatitis

Learn about the types, symptoms, causes and treatments — moisturizers and medications — for this itchy skin condition that affects people of all ages.

Dermatofibrosarcoma protuberans

Learn about symptoms and diagnosis for this rare type of skin cancer. DFSP treatments include Mohs surgery, radiation and targeted therapy.

Dermatographia

Dermatographia — Comprehensive overview covers symptoms, treatment of this skin condition.

Dermatomyositis

Muscle weakness and a skin rash are hallmarks of dermatomyositis. There's no cure, but treatments can relieve symptoms.

Desmoid tumors

Learn how doctors use surgery, radiation therapy, chemotherapy and other medications to treat desmoid tumors, also known as aggressive fibromatosis.

Deviated septum

Learn how uneven nostrils can cause congestion, nosebleeds or other symptoms in severe cases.

DiGeorge syndrome (22q11.2 deletion syndrome)

DiGeorge syndrome (22q11.2 deletion syndrome) is a disorder caused by a defect in chromosome 22, resulting in poor development of several body systems.

Diabetes

Learn more about the different types of this blood sugar disorder, who's at risk and how each type can be treated.

Diabetes insipidus

Learn more about this unusual disorder that disrupts the body's fluid balance, causing excessive urination and possibly leading to dehydration.

Diabetic coma

Diabetic coma is a life-threatening diabetes complication. Learn about its causes, treatment and prevention.

Diabetic hyperosmolar syndrome

Learn more about the symptoms, treatment and prevention of this life-threatening diabetes complication caused by extremely high blood sugar levels.

Diabetic hypoglycemia

Low blood sugar can make you feel awful and is potentially dangerous. Learn about low blood sugar symptoms and treatments for someone with diabetes.

Diabetic ketoacidosis

Learn more about the symptoms, treatment and prevention of this serious diabetes complication.

Diabetic nephropathy (kidney disease)

Diabetic nephropathy is a common complication in people with diabetes. Learn how managing your diabetes may prevent or delay damage to your kidneys.

Diabetic neuropathy

High blood sugar can lead to nerve damage in feet and other areas of the body. Know the signs and how to take steps to prevent this diabetes complication.

Diabetic retinopathy

Good diabetes control and regular exams can help prevent this diabetes complication that affects the eyes. Find out how.

Diaper rash

Dealing with diaper rash? Follow these tips to soothe your baby's irritated skin.

Diarrhea

Learn more about what causes this common, unpleasant digestive condition, and how you can treat and prevent it.

Diffuse idiopathic skeletal hyperostosis (DISH)

Bony hardening of ligaments where they attach to your spine might cause no symptoms, or it can cause progressive pain and stiffness.

Dilated cardiomyopathy

In this heart muscle disease, the heart's main pumping chamber stretches and can't pump blood well. Learn about the causes and treatment.

Diphtheria

This rare but serious bacterial infection can cause organ damage and breathing problems. This disease is often treatable but is also preventable with a vaccine.

Dislocated elbow

Dislocated elbow — Comprehensive overview covers symptoms, causes, treatments of this common elbow injury.

Dislocated shoulder

Dislocated shoulder — Comprehensive overview covers symptoms, causes and treatment of this shoulder injury.

Dissociative disorders

Dissociative disorders are mental disorders that involve experiencing a disconnection between thoughts, memories, surroundings, actions and identity.

Diverticulitis

This common colon disease develops when small pouches form in the colon wall and become infected, causing pain, fever and abnormal bowel function.

Dizziness

Dizziness has many possible causes. How long it lasts and any other symptoms you have can help pinpoint the cause.

Double uterus

Learn about symptoms, diagnosis and treatment of this uncommon abnormality of the uterus that's present at birth.

Double-outlet right ventricle

Learn about this heart condition that's present at birth in which two major blood vessels aren't attached to the heart in the proper positions.

Down syndrome

Down syndrome is a genetic disorder caused when abnormal cell division results in extra genetic material from chromosome 21.

Dressler syndrome

Learn about the symptoms and treatment of inflammation of the sac surrounding the heart in post-cardiac injury syndromes.

Drug addiction (substance use disorder)

With drug addiction (substance use disorder), you can't control your use of legal or illegal drugs or alcohol and may continue using despite the harm it causes.

Drug allergy

Learn which drugs are more likely to cause an allergic reaction, what symptoms look like and what treatments can calm such a reaction.

Dry eyes

Dry eyes is a common — and very treatable — condition. Find out what causes dry eyes and how to relieve symptoms.

Dry macular degeneration

Blurred or reduced central vision could be a sign of macular degeneration. Find out about symptoms and treatment for this common eye disorder.

Dry mouth

Dry mouth (xerostomia) refers to a condition in which the salivary glands in your mouth don't make enough saliva to keep your mouth wet.

Dry skin

Learn more about the causes of and self-care tips for a common flaky skin condition that tends to be temporary or seasonal but may become a lifelong problem.

Dry socket

Dry socket, a painful dental condition, occurs when the blood clot at the site of a tooth extraction dislodges or dissolves before the wound has healed.

Ductal carcinoma in situ (DCIS)

Noninvasive breast cancer often has no signs or symptoms. Find out how doctors diagnose DCIS and learn about treatment, including mastectomy and lumpectomy.

Dumping syndrome

People who have had stomach or weight-loss surgery can develop dumping syndrome, which causes cramping, diarrhea and, sometimes, low blood sugar.

Dupuytren's contracture

Dupuytren's contracture — Comprehensive overview covers symptoms, risk factors, treatment of this hand condition.

Dural arteriovenous fistulas

Treatments for these abnormal connections between an artery and the brain's dura include endovascular embolization and stereotactic radiosurgery.

Dust mite allergy

Dust mite allergy can lead to year-round sniffles and sneezes. Here's how to find relief.

Dwarfism

Very short stature of 4 feet 10 inches or less that results from a genetic or medical condition is considered dwarfism. Learn about causes and treatment.

Dysarthria

This condition affects muscles used for speaking. Speech therapy and treating the underlying cause may improve speech.

Dyshidrosis

Learn about the symptoms, causes and treatment of this skin condition that causes little blisters on the hands.

Dyslexia

Dyslexia is a learning disorder involving difficulty reading due to problems identifying speech sounds and learning how they relate to letters and words.

Dysphagia

Learn more about what causes persistent trouble swallowing, along with therapies for treating this condition.

Dystonia

Find out more about this painful muscle contraction disorder and ways to improve muscle function.

E. coli

Most strains of E. coli bacteria are harmless, but some can cause severe symptoms. Learn about symptoms and treatment of this common foodborne illness.

Ear infection (middle ear)

These usually get better on their own, but sometimes medicine is needed. Find out more about how doctors diagnose and treat this common ear condition.

Earwax blockage

Learn simple steps for treatment and self-care of this common problem, including earwax removal.

Eating disorders

Eating disorders, such as anorexia, bulimia and binge-eating disorder, seriously impact health. Learn about symptoms and treatments.

Ebola virus and Marburg virus

Understand the causes and symptoms of these tropical viruses, and tips to prevent illness.

Ebstein anomaly

In this rare heart defect, the tricuspid heart valve didn't form properly. This can affect the heart's ability to pump blood. Know the risks and symptoms.

Ectopic pregnancy

Ectopic pregnancy occurs outside the uterus, threatening the mother's life. It can't continue normally. But swift treatment can prevent deadly blood loss.

Ectropion

Ectropion is an eye condition in which your eyelid sags or turns outward. Find out about causes and treatment for this common eye problem.

Edema

Learn about symptoms, causes and treatment of edema — swelling caused by excess fluid in body tissues — as well as home remedies that could ease swelling.

Egg allergy

Egg allergy can cause a serious reaction in children and adults. Here's how to recognize egg allergy symptoms, and what to do if a severe reaction occurs.

Ehlers-Danlos syndrome

Learn about these complex genetic disorders that cause problems with connective tissue in the skin, joints and blood vessel walls.

Ehrlichiosis and anaplasmosis

Learn how to prevent and treat the tick-borne diseases ehrlichiosis and anaplasmosis.

Eisenmenger syndrome

There's no cure for this serious complication of a heart defect, but treatments help control symptoms and improve quality of life.

Elevated blood pressure

If your blood pressure is slightly elevated, eating better and moving more can help prevent prehypertension from becoming high blood pressure.

Embryonal tumors

Embryonal tumors include medulloblastomas, embryonal tumors with multilayered rosettes, medulloepitheliomas, atypical teratoid/rhabdoid tumors, and PNETs.

Emphysema

Emphysema is a lung problem that makes it hard to catch your breath. It's one of the conditions that make up chronic obstructive pulmonary disease (COPD).

Encephalitis

Learn about this potentially life-threatening condition associated with inflammation of the brain and what you can do to prevent the condition.

Encopresis

Encopresis, also called fecal incontinence or soiling, occurs when constipation causes impacted stool to fill the colon, and liquid stool leaks out.

End-stage renal disease

When kidneys no longer function well enough to meet a body's needs, treatment involves kidney dialysis or kidney transplant.

Endocarditis

Learn what causes this infection of the inner lining of the heart chambers and valves (endocardium) and find out how to prevent and treat it.

Endometrial cancer

Learn about the symptoms and causes of this cancer of the uterus. Treatments include hysterectomy, radiation therapy, chemotherapy and other drug treatments.

Endometriosis

Learn about endometriosis, including possible treatments for this condition that causes pain and sometimes infertility in many women.

Enlarged breasts in men (gynecomastia)

Learn how an imbalance of the hormones estrogen and testosterone can cause swelling of the breast tissue in boys or men.

Enlarged heart

Cardiomegaly is another word for this sign or symptom that may be caused by certain heart conditions or even pregnancy. Know how it's treated.

Enlarged liver

Having a larger than normal liver is a sign of a serious problem, such as liver disease, congestive heart failure or cancer.

Enlarged spleen (splenomegaly)

Learn about what your spleen does and what can happen if it becomes enlarged.

Entropion

In entropion, your eyelid turns inward, causing lashes and skin to rub against the eye. Learn about causes and treatment for this irritating eye condition.

Eosinophilic esophagitis

Learn more about the causes and treatment of eosinophilic esophagitis — a digestive disease caused by an allergic reaction.

Ependymoma

Learn about this tumor that forms from ependymal cells in the brain and spinal cord. Treatments include surgery and radiation therapy.

Epidermoid cysts

Find out more about this usually harmless, common skin bump in adults.

Epidermolysis bullosa

Learn about this group of inherited skin diseases that often shows up in infancy and cause fragile, blistering skin. Severe forms may be life-threatening.

Epididymitis

Males of any age can get epididymitis, an inflammation of the coiled tube (epididymis) at the back of the testicle that stores and carries sperm. It's usually caused by a bacterial infection.

Epiglottitis

Prompt treatment is essential for a blocked windpipe.

Epilepsy

Learn about epilepsy symptoms, possible causes of epilepsy and how epilepsy is treated, including surgical treatment options.

Epithelioid sarcoma

This rare, slow-growing soft tissue cancer tends to occur in teenagers and young adults — often in a hand, wrist, arm or leg, but it can start in other areas.

Erectile dysfunction

Understand what can cause the inability to get and keep an erection firm enough for sex and the possible treatment options.

Esophageal cancer

Esophageal cancer — Comprehensive overview covers symptoms, causes, treatment of cancer of the esophagus.

Esophageal spasms

This digestive condition is sometimes mistaken for heart pain. Learn about symptoms and treatment for these painful contractions in the esophagus.

Esophageal varices

Learn how to spot and what to do if you experience signs of this serious complication of liver disease.

Esophagitis

Learn more about the causes and treatment of inflammation of the esophagus.

Essential thrombocythemia

This disorder causes your body to make too many platelets, a sticky component of blood cells. Having too many platelets increases your risk of blood clots.

Essential tremor

Learn about this disorder that causes uncontrollable shaking, and find out how it differs from Parkinson's disease.

Esthesioneuroblastoma

Find out about this rare cancer that begins in the upper portion of the nasal cavity. Learn about symptoms and treatments, including minimally invasive surgery.

Ewing sarcoma

Learn about diagnosis and treatment of this bone and soft tissue cancer, including chemotherapy, radiation, proton beam therapy and limb-saving surgery.

Exercise headaches

Learn about the causes and treatments of this puzzling disorder.

Exercise-induced asthma

Regular exercise is beneficial in many ways, but for some people, exercise can trigger breathing problems. Medication can help.

Eye floaters

Many people over age 50 experience eye floaters. Learn more about this common problem, including causes, other risk factors and treatment options.

Eye melanoma

Eye melanoma is a type of eye cancer. Learn about symptoms and treatments for this rare cancer. It's also called ocular melanoma or uveal melanoma.

Eyestrain

Gazing for long stretches at computer or digital screens is a frequent eyestrain culprit. Find out how to relieve — and prevent — this common problem.

Factitious disorder

Factitious disorder ― a serious mental disorder in which someone deceives others by appearing sick, by purposely getting sick or by self-injury.

Factor V Leiden

This inherited clotting disorder can increase your chance of developing abnormal blood clots, most commonly in your legs or lungs.

Familial Mediterranean fever

This genetic autoinflammatory disorder causes recurrent fevers and painful inflammation. Treatment can prevent attacks and complications.

Familial adenomatous polyposis

This inherited condition leads to colon cancer. Treatment consists of having frequent screenings and having surgery to remove all or part of the colon.

Familial hypercholesterolemia

This inherited condition can cause extremely high levels of "bad" cholesterol, even in childhood, and can lead to early heart attacks and death.

Farsightedness

Do you see distant objects clearly, but develop a blur as they come close? This vision problem, called farsightedness, is easily corrected with prescription lenses.

Febrile seizure

These frightening but generally harmless seizures are triggered by a fever and affect infants and young children.

Fecal incontinence

Learn about this common but potentially embarrassing problem that causes some people to avoid social situations. Treatments are available.

Female infertility

Learn about infertility in women, including possible causes, what tests might be needed and fertility treatments available to help with getting pregnant.

Female sexual dysfunction

Learn more about female sexual difficulties — what causes them and possible treatments, including medications.

Fetal alcohol syndrome

Fetal alcohol syndrome results from alcohol exposure during the mother's pregnancy, causing irreversible brain damage and growth problems in the child.

Fetal macrosomia

When a baby in utero grows much larger than average for gestational age, it can lead to complications during childbirth for both mother and baby.

Fever

Medications can lower a fever, but sometimes it's better left untreated. Fever may play a role in helping your body fight off infections.

Fibroadenoma

A fibroadenoma is a type of noncancerous (benign) breast lump. Unless you have symptoms that bother you, treatment might not be needed.

Fibrocystic breasts

Learn about this condition that's common in women, including symptoms, possible causes and testing to determine when breast cysts might need treatment.

Fibromuscular dysplasia

Learn more about this condition that can narrow different arteries, including ones that supply blood to your kidneys, brain, heart or abdomen.

Fibromyalgia

This complicated disorder amplifies painful sensations by affecting the way your brain processes pain signals. Medications, therapy and exercise can help.

Fibrous dysplasia

Fibrous dysplasia — Irregular bone growths can cause pain, bone deformities or fractures. Treatments may manage pain and stabilize bones.

Flatfeet

Flatfeet — Comprehensive overview covers causes, treatment of this often symptomless foot condition.

Floor of the mouth cancer

Learn about the symptoms of this type of cancer that forms under your tongue. Floor of the mouth cancer treatments include surgery, radiation and chemotherapy.

Folliculitis

Learn more about how damaged hair follicles become infected. This condition may clear up on its own, but severe infections can cause scarring or hair loss.

Food allergy

For people with food allergies, symptoms can range from annoying to life-threatening. Learn about diagnosis and treatment of this common immune reaction.

Food poisoning

Learn more about this foodborne illness that can cause nausea, vomiting and diarrhea within hours of eating contaminated food.

Foot drop

Foot drop is a general term that describes a difficulty in lifting the front part of the foot. It's often caused by compression of a nerve.

Frontal lobe seizures

In this common form of epilepsy, the seizures stem from the front of the brain. They can produce symptoms that appear to be psychiatric.

Frontotemporal dementia

Read more about this less common type of dementia that can lead to personality changes, speech difficulties and movement problems.

Frostbite

Learn how to prevent cold injury to the skin when outdoors in freezing temperatures and how to treat and recover from frostbite.

Frozen shoulder

Frozen shoulder — Comprehensive overview covers symptoms, causes and treatment of this painful joint condition.

Fuchs' dystrophy

Fuchs' dystrophy can cause eye pain and vision problems that worsen over time. Medications can help symptoms, but surgery may offer long-term relief.

Functional dyspepsia

Feeling burning stomach pain or other ulcer symptoms with no detectable cause? A range of treatments can offer relief for this common digestive disorder.

Functional neurologic disorder/conversion disorder

This disorder includes nervous system symptoms affecting movement or the senses that are not caused by medical disease. Treatment can help with recovery.

Galactorrhea

Galactorrhea is a type of milky nipple discharge in people who aren't breast-feeding. Find out more about the possible causes and treatments.

Gallbladder cancer

Learn about this cancer that begins in the gallbladder. Treatment typically involves surgery. Chemotherapy and radiation therapy may be options.

Gallstones

Gallstones are hard pieces of material that can form in your gallbladder. Learn about causes and treatment for this sometimes painful digestive disorder.

Ganglion cyst

Ganglion cysts — Comprehensive overview covers causes, treatment of lumps on wrist, hand or foot.

Gangrene

A severe bacterial infection or lack of blood flow can cause body tissue to die. Know the warning signs and symptoms of this life-threatening condition.

Gas and gas pains

Learn about what is normal digestive system gas, what contributes to gas, and what you can do to lessen gas or gas pains.

Gastritis

Gastritis — inflammation of the stomach lining — has many possible causes. Find out how to relieve the distressing symptoms.

Gastroesophageal reflux disease (GERD)

GERD, in which stomach acid moves into the esophagus, causes discomfort and may lead to precancerous changes in the lining of the esophagus.

Gastrointestinal bleeding

Bleeding from anywhere in your digestive tract is a symptom of a disorder. Bleeding can be hidden or obvious, slight or severe.

Gastrointestinal stromal tumor (GIST)

Learn about this type of cancer that usually happens in the stomach or small intestine. Treatments often include surgery and targeted therapy.

Gastroparesis

Learn about symptoms and treatment for gastroparesis — a digestive condition that affects muscles in your stomach and prevents it from emptying properly.

Gaucher disease

An enzyme that breaks down certain fatty substances doesn't work properly in people with Gaucher disease. Enzyme replacement therapy often helps.

Gender dysphoria

Learn about the treatments that can help alleviate discomfort that can arise when there's a difference between gender identity and sex assigned at birth.

Generalized anxiety disorder

Excessive, ongoing anxiety and worry can interfere with your daily activities and may be a sign of generalized anxiety disorder, but treatment can help.

Genital herpes

Genital herpes — Comprehensive overview covers symptoms, treatment of this highly contagious disease.

Genital warts

The human papillomavirus (HPV) causes the most common of sexually transmitted infections. Vaccines can help protect against the HPV strains that cause genital warts.

Geographic tongue

Geographic tongue may look alarming, but it doesn't cause health problems. It can sometimes cause tongue discomfort and more sensitivity to certain foods.

Gestational diabetes

This high blood sugar disorder develops during pregnancy and can affect your pregnancy and your baby's health. Read about risks, prevention and treatment.

Giant cell arteritis

Head pain and tenderness are the most common symptoms of giant cell arteritis, an inflammation of the lining of your arteries.

Giardia infection (giardiasis)

Stomach cramps, nausea and watery diarrhea could indicate a giardia infection. Find out how to treat and prevent this waterborne parasite.

Gilbert's syndrome

This inherited liver condition affects the liver's ability to break down red blood cells. It usually has no serious medical consequences.

Gingivitis

Gingivitis is a common and mild form of gum disease that causes irritation, redness and swelling of your gums.

Glaucoma

Having regular eye exams can help catch glaucoma early and save your eyesight. Find out about symptoms and treatment for this vision-stealing eye disease.

Glioblastoma

Learn about this aggressive cancer that can occur in the brain or spinal cord. Glioblastoma treatments include surgery, radiation and chemotherapy.

Glioma

Gliomas are among the most common types of brain cancer. Learn more about diagnosis and treatment, including innovative research to find new therapies.

Glomerulonephritis

Learn about symptoms, causes and treatments for acute and chronic glomerulonephritis, a type of kidney inflammation.

Goiter

Enlargement of the thyroid gland may be caused by autoimmune disorders, an iodine-poor diet, pregnancy-related hormones and other factors.

Golfer's elbow

Golfers, tennis players and others who repeatedly use their wrists or clench their fingers can develop this painful condition.

Gonorrhea

This common sexually transmitted infection often causes no signs or symptoms. Learn more about treatment, prevention and possible complications.

Gout

This type of arthritis can cause sudden, severe attacks of pain, swelling, redness and tenderness — often in the big toe.

Grand mal seizure

Learn all about grand mal seizures — the type of seizure that can cause convulsions — and how to help if you see someone having one.

Granuloma annulare

Learn about this painless skin condition mainly affecting young adults in which bumps form a ring. The rash can be long lasting or recur after treatment.

Granulomatosis with polyangiitis

Granulomatosis with polyangiitis causes inflammation in the blood vessels in your nose, sinuses, throat, lungs and kidneys. Prompt treatment is vital.

Graves' disease

Learn about the symptoms, causes and treatment of this immune system disorder that results in the overproduction of thyroid hormones (hyperthyroidism).

Greenstick fractures

Greenstick fractures — Comprehensive overview covers symptoms, diagnosis and treatment of this childhood bone injury.

Group B strep disease

This common bacterium, usually harmless in healthy adults, can cause serious illness in newborns and adults with certain chronic conditions, such as diabetes.

Growing pains

Learn about this common condition involving leg pain in children, including growing pain symptoms and how to ease discomfort.

Growth plate fractures

Growth plate fractures — This common childhood bone injury often needs immediate treatment as it can result in a shorter, longer or crooked limb.

Guillain-Barre syndrome

This rare autoimmune disorder affects the nerves, causing weakness and tingling in the arms and legs that rapidly spreads throughout the body.

H1N1 flu (swine flu)

Find out more about the flu caused by the H1N1 virus. Learn how to prevent and treat the flu.

HIV/AIDS

Learn more about this potentially life-threatening infection that spreads through blood, sex and childbirth. Know how to prevent and treat it.

HPV infection

This common viral infection often gets better on its own, but when it doesn't, it may cause a variety of warts and can even lead to some cancers.

Hair loss

This common and sometimes stressful condition may result from heredity, medications or medical conditions. Treatment may reverse or slow hair loss.

Hairy cell leukemia

This slow-growing cancer doesn't always need immediate treatment. Learn how doctors decide to start chemotherapy and biological therapy for hairy cell leukemia.

Hammertoe and mallet toe

Hammertoe and mallet toe — Comprehensive overview covers causes, symptoms and treatment of these foot deformities.

Hamstring injury

Hamstring injury — Comprehensive overview covers symptoms, treatments, self-care, prevention of this leg muscle injury.

Hand-foot-and-mouth disease

Learn about the symptoms and treatment of this contagious viral infection that's characterized by sores in the mouth and a rash on the hands and feet.

Hangovers

Unpleasant signs and symptoms can develop after drinking too much alcohol — but severe signs may indicate alcohol poisoning, a life-threatening emergency.

Hantavirus pulmonary syndrome

Learn about the rodent-transmitted virus that causes severe — and sometimes fatal — lung disease with flu-like symptoms that can rapidly worsen.

Hashimoto's disease

Learn about the symptoms and treatment of this thyroid disorder caused by an immune-system dysfunction.

Hay fever

Find out more about how to diagnose and get relief from this common condition that can make you feel awful, seasonally and year-round.

Head lice

Find out how these tiny insects that feed on blood from the human scalp can spread from person to person, along with treatment options.

Headaches in children

Find out more about headaches in children, which may or may not be serious. They can often be managed with medications and healthy habits.

Hearing loss

Age- and noise-related hearing loss are common and can affect quality of life. But many treatments are available.

Heart arrhythmia

Learn about common heart rhythm disorders that can cause your heart to beat too fast, too slow or irregularly.

Heart attack

A blockage of blood flow to the heart can damage or destroy heart muscle.

Heart disease

Learn about symptoms, causes and treatment of heart disease, a term describing a wide range of conditions that can affect the heart.

Heart failure

Learn about this chronic disease that needs lifelong management, and find out what treatments help you live longer and may even strengthen your heart.

Heart murmurs

Learn about symptoms, causes and treatments of abnormal heart sounds.

Heart palpitations

Know when and how feelings of a rapid, fluttering or pounding heartbeat are treated.

Heart valve disease

Learn about this condition in which one or more of your heart valves doesn't work properly.

Heartburn

Occasional heartburn is a common, manageable condition — but when is it a problem?

Heat exhaustion

An overheated body can lead to dangerous symptoms. Get tips to prevent heat exhaustion and how to cool down quickly when it happens.

Heat rash

Learn more about the symptoms, causes and treatment of this heat-related problem of the skin that affects people of all ages.

Heatstroke

Know the signs and what to do for this dangerous increase in body temperature.

Helicobacter pylori (H. pylori) infection

Learn more about the symptoms, tests and treatments of this infection with Helicobacter pylori bacteria.

Hemangioma

Learn more about the causes and treatment of this red mark on the skin of babies that fades over time.

Hemifacial spasm

Learn about diagnosis and treatment of this nervous system disorder that causes muscles to twitch on one side of the face.

Hemochromatosis

Hemochromatosis is a condition in which your body stores too much iron. Learn about symptoms, causes and treatment of this inherited liver disorder.

Hemolytic uremic syndrome (HUS)

Damage to the small blood vessels in the kidneys can cause clots that clog the organ’s filtering system. This can lead to life-threatening kidney failure.

Hemophilia

In this inherited disorder, the blood lacks one of several clot-forming proteins. The result is prolonged bleeding, which can be life-threatening.

Hemorrhoids

There are many effective options for easing the discomfort of hemorrhoids — swollen veins in your anus and lower rectum.

Henoch-Schonlein purpura

Learn about the symptoms, causes and treatment of this blood vessel disease, also called IgA vasculitis, that causes a purplish rash on the lower legs.

Hepatitis A

Hepatitis A is a contagious liver infection caused by a virus. Learn more about its symptoms, treatment and prevention, including hepatitis A vaccine.

Hepatitis B

Hepatitis B is a contagious liver infection caused by a virus. It may become long lasting. Know the symptoms, treatment and prevention of hepatitis B.

Hepatitis C

Many people with hepatitis C don't even know they're infected. Find out about symptoms and treatment for this potentially dangerous liver disease.

Hepatocellular carcinoma

Learn about innovative treatments for the most common type of liver cancer (hepatocellular carcinoma, or HCC), including liver transplant and ablation.

Hepatopulmonary syndrome

This lung condition causes low oxygen levels and shortness of breath in people who have advanced liver disease.

Hereditary hemorrhagic telangiectasia

This inherited blood vessel disorder can cause severe nosebleeds, strokes, bleeding in the digestive tract and anemia.

Herniated disk

This condition occurs most often in the lower back. In many cases, it causes no symptoms and requires no treatment. Surgery is rarely needed.

Hiatal hernia

A hiatal hernia occurs when part of the stomach bulges into the chest. It can cause severe heartburn but is treatable.

Hiccups

Caused by contractions of your diaphragm, hiccups are usually harmless. But rarely, hiccups may be a sign of an underlying medical problem.

Hidradenitis suppurativa

Learn more about the causes, symptoms and treatments of this long-term condition that causes painful lumps and tunnels under the skin.

High blood pressure (hypertension)

Learn the symptoms and treatment of this condition — which raises your risk of heart attack and stroke — and the lifestyle changes that can lower the risk.

High blood pressure in children

Children can develop high blood pressure for the same reasons adults do — excess weight, poor nutrition and lack of exercise.

High cholesterol

You need some cholesterol in your blood to build healthy cells. But high cholesterol can increase your risk of heart disease. Lifestyle changes can help.

Hilar cholangiocarcinoma

Learn about how this type of bile duct cancer is diagnosed and treated.

Hip dysplasia

In infancy, this condition often can be corrected with a soft brace. Older children and young adults might require surgery to correct the misalignment.

Hip fracture

The risk of breaking a hip increases with age. Learn about lifestyle changes that can keep bones strong and reduce risk of breaking.

Hip labral tear

Sports such as soccer, football and golf can increase your risk of damaging the ring of cartilage that helps cushion and stabilize your hip joint.

Hirschsprung's disease

This digestive disorder that's present at birth affects the nerves in the colon. It causes severe constipation but can be treated.

Hirsutism

Learn more about causes and complications of unwanted excess hair in women and what self-care methods and medical treatments are effective.

Histoplasmosis

Learn more about the symptoms and treatment of this sometimes life-threatening fungal disease caused by spores in bird and bat droppings.

Hives and angioedema

Learn more about these common but short-lived skin conditions, their symptoms, causes and home remedies, and how to prevent them.

Hoarding disorder

Hoarding disorder is a persistent difficulty discarding or parting with possessions because of a perceived need to save them.

Hodgkin's lymphoma (Hodgkin's disease)

Learn how this cancer differs from other lymphomas. Find out about risk factors and treatments, such as chemotherapy, radiation and bone marrow transplant.

Horner syndrome

Find out about Horner syndrome, an interruption in nerve signals from the brain to the eye and face on one side of the body.

Hot flashes

Hot flashes are the most common symptom of menopause. Learn about strategies for relief of hot flashes, including hormone therapy and natural remedies.

Hunter syndrome

This rare metabolic disorder can affect the lungs, heart, joints, connective tissue, brain and nervous system. Treatments may help complications.

Huntington's disease

This condition causes a progressive breakdown of nerve cells in the brain. Find out about what signs to watch for and how treatments may help.

Hurthle cell cancer

Learn about this rare type of aggressive thyroid cancer. Treatment typically involves surgical removal of the thyroid gland.

Hydrocele

Find out more about the symptoms, causes and possible treatments for this swelling in the scrotum.

Hydrocephalus

Read more about this potentially fatal disorder that causes fluid buildup in the brain — resulting in a range of symptoms, from headaches to poor balance.

Hydronephrosis

Learn about this condition that occurs when urine doesn't drain properly from the upper urinary tract, leading to kidney swelling.

Hypercalcemia

Hypercalcemia can weaken your bones, create kidney stones, and interfere with how your heart and brain work. Treatment depends on the cause.

Hypereosinophilic syndrome

Hypereosinophilic syndrome is a disorder of certain types of white blood cells that can cause life-threatening damage to your organs.

Hyperglycemia in diabetes

Hyperglycemia in diabetes can occur for many reasons. Know the causes, symptoms and treatments of high blood sugar and when to get emergency help.

Hyperhidrosis

Learn more about causes, symptoms, treatment and self-care tips for this embarrassing condition that causes heavy sweating unrelated to heat or exercise.

Hyperoxaluria and oxalosis

Learn about symptoms, causes, diagnosis and treatment for this rare kidney disorder, which develops in people who have too much oxalate in the urine.

Hyperparathyroidism

Learn about symptoms, tests and treatment for this condition caused by overactivity of the parathyroid gland.

Hyperthyroidism (overactive thyroid)

Learn more about the consequences of an overactive thyroid, along with various treatment options available for this condition.

Hypertrophic cardiomyopathy

In this condition, the heart muscle thickens, which makes it harder for the heart to pump blood. Learn about the causes and treatment.

Hypoglycemia

Low blood sugar can cause uncomfortable symptoms, such as dizziness and confusion, and can quickly become serious if left untreated.

Hyponatremia

Hyponatremia is the term used when your blood sodium is too low. Learn about symptoms, causes and treatment of this potentially dangerous condition.

Hypoparathyroidism

Learn more about this uncommon condition in which low levels of parathyroid hormone upsets the balance of calcium and phosphorus in your body.

Hypopituitarism

Learn about the symptoms and treatment of this rare hormonal disorder caused by a problem with the pituitary gland.

Hypoplastic left heart syndrome

Learn more about this rare congenital heart condition that results in underdevelopment of the left side of the heart.

Hypospadias

Hypospadias is a birth defect in which the opening of the urethra is located on the underside of the penis instead of the tip. Learn about treatment.

Hypothermia

Learn about symptoms, treatment and prevention of hypothermia — a life-threatening condition in which the body loses heat faster than it can generate it.

Hypothyroidism (underactive thyroid)

Feeling sluggish? Gaining unexpected weight? Your thyroid gland may not be working effectively. Learn more about causes and treatments of this condition.

Ichthyosis vulgaris

Ichthyosis vulgaris — Comprehensive overview covers signs, symptoms, causes, diagnosis and treatment.

Idiopathic hypersomnia

Idiopathic hypersomnia is a sleep disorder that causes you to be excessively sleepy during the day and to have trouble waking up from sleep.

IgA nephropathy (Berger's disease)

This disease causes kidney inflammation that, over time, can interfere with your kidneys' ability to filter waste from your blood.

Illness anxiety disorder

Excessive worry that you're seriously ill based on minor symptoms can result in major emotional distress and disrupt your life. Also called hypochondria.

Immune thrombocytopenia (ITP)

Caused by low levels of platelets, symptoms may include purple bruises called purpura, as well as tiny reddish-purple dots that look like a rash.

Impacted wisdom teeth

Impacted wisdom teeth — Learn about symptoms, complications and treatment of impacted wisdom teeth.

Impetigo

Learn about the symptoms, causes and treatment of this highly contagious bacterial skin infection common in infants and young children.

Incompetent cervix

Sometimes the cervix opens and thins early, making it unable to support a pregnancy. Learn more about this difficult-to-diagnose condition.

Indigestion

Is it indigestion or something else? Find out about causes, symptoms and treatment for this common digestive disorder.

Infant jaundice

Learn about this common condition in newborns, especially those born preterm. With close monitoring and light therapy, complications are rare.

Infant reflux

This common and messy condition is usually harmless. Most babies outgrow it by age 18 months.

Infectious diseases

Viruses, bacteria, fungi and parasites can all cause infection. Find out more about how to prevent and treat these conditions.

Infertility

Find out about the challenges of infertility, when to seek help, causes, risk factors, and treatments including insemination and in vitro fertilization.

Inflammatory bowel disease (IBD)

Chronic diarrhea and belly pain could be caused by inflammatory bowel disease. Learn about IBD causes, diagnosis and treatment.

Inflammatory breast cancer

Learn about this rare, aggressive type of breast cancer that causes a red, swollen breast. Treatments include surgery, radiation, chemotherapy and others.

Influenza (flu)

Learn more about the symptoms, causes and prevention of this potentially fatal viral infection that attacks the respiratory system.

Ingrown hair

Learn about causes, treatment and prevention of this common, painful skin condition — sometimes called razor bumps, barber's itch, shave bumps and pseudofolliculitis barbae.

Ingrown toenails

Learn about causes, prevention and treatment of this common, painful nail condition that usually affects the big toe.

Inguinal hernia

What happens if part of the intestine bulges through a weak spot in abdominal muscle? This condition can be painful and often requires surgery to fix.

Insomnia

Insomnia is a disorder that can make it hard to fall asleep, hard to stay asleep, or cause you to wake up too early and not be able to get back to sleep.

Intermittent explosive disorder

This mental disorder involves repeated, sudden episodes of impulsive, aggressive, violent behavior or verbal outbursts that cause major distress in life.

Interstitial cystitis

Bladder pain and urinary frequency flare with certain triggers if you have this condition. Learn about treatments and self-care.

Interstitial lung disease

In interstitial lung disease, progressive lung can cause permanent breathing problems. Learn the causes, including many toxins in the environment.

Intestinal ischemia

Learn more about what happens when blood flow to part of the digestive system is reduced, and how this serious condition is treated.

Intestinal obstruction

A blocked intestine needs prompt medical care. Learn about symptoms and the wide range of causes for this serious but treatable digestive disorder.

Intracranial hematoma

This collection of blood within the skull is a serious, possibly life-threatening, complication of head trauma.

Intracranial venous malformations

Intracranial venous malformations are abnormally enlarged veins in your brain. Find out more about diagnosis and treatment of this neurological condition.

Intussusception

This rare but serious disorder occurs when one part of the intestine slides into another part, like a collapsible telescope.

Invasive lobular carcinoma

Breast cancer that begins in the milk-producing glands of the breast is uncommon. Learn what sets lobular carcinoma apart from other breast cancer types.

Iritis

Learn about who's at risk of this eye condition and why you should get treatment right away if you have symptoms.

Iron deficiency anemia

Iron deficiency anemia — Comprehensive overview covers symptoms, causes, treatment of this blood disorder.

Irritable bowel syndrome

Find out about irritable bowel syndrome symptoms and diagnosis. Often, lifestyle changes help manage this common, chronic bowel disorder.

Ischemic colitis

Ischemic colitis occurs when a part of the colon experiences a decrease in blood flow. It can cause serious complications but usually resolves on its own.

Itchy skin (pruritus)

Learn about causes of this common irritating skin condition and which treatments and self-care measures may provide relief.

Jaw tumors and cysts

Also called odontogenic tumors and cysts, these typically benign lesions develop in the jawbone or the soft tissues in the mouth. They vary in severity.

Jellyfish stings

Learn more about prevention and first aid for these painful injuries that are common among people swimming in seawater and are rarely life-threatening.

Jet lag disorder

Jetting across time zones can take a toll on your body's internal clock. Here's how to cope with fatigue and other symptoms while traveling.

Jock itch

Learn more about this common treatable fungal infection that causes a red itchy rash in the groin and inner thighs.

Juvenile idiopathic arthritis

Learn about this type of arthritis that affects children and can cause growth problems, joint damage and eye inflammation.

Kaposi's sarcoma

Kaposi's sarcoma, a cancer caused by a virus, occurs in AIDS and in transplant patients taking anti-rejection drugs. It appears as purplish skin spots.

Kawasaki disease

Learn more about this condition that primarily affects young children and causes inflammation in the walls of the arteries throughout the body.

Keloid scar

Learn about how to prevent, remove or flatten these problematic raised scars that form over scars from acne, tattoos, piercing and other injuries.

Keratitis

An inflamed, red eye could mean you have keratitis. Find out how to spot and treat this potentially dangerous eye problem.

Keratoconus

Keratoconus occurs when your cornea bulges outward, causing vision problems. Find out about symptoms, causes and treatment for this eye condition.

Keratosis pilaris

Find out more about this harmless, nonitchy skin condition that causes bumpy, rough skin on the upper arms, thighs or buttocks.

Kidney cancer

Learn about the symptoms and causes of kidney cancer and renal cell carcinoma. Find out about treatments, such as nephrectomy and immunotherapy.

Kidney cysts

Kidney cysts — round pouches of fluid on or in the kidneys — are sometimes discovered during routine imaging exams. Learn when treatment may be needed.

Kidney infection

A urinary tract infection that travels to your kidneys can be dangerous. Seek prompt medical treatment if you develop signs and symptoms.

Kidney stones

Learn about the symptoms, risks, causes and treatment of this often intensely painful condition.

Kleptomania

Kleptomania is the recurrent inability to resist urges to steal items that you generally don't really need and that usually have little value.

Klinefelter syndrome

This genetic disorder occurs when a male is born with an extra copy of the X chromosome and may result in low testosterone production and infertility.

Klippel-Trenaunay syndrome

Main signs of this congenital disorder involve a red birthmark (port-wine stain), vein malformations, and overgrowth of tissues and bones.

Knee bursitis

Knee bursitis is inflammation of a small fluid-filled sac (bursa) situated near your knee joint. Knee bursitis causes pain and can limit your mobility.

Knee pain

Learn about this common complaint, which can result from an injury or medical condition, and find out which treatments may help.

Krabbe disease

Find out more about this rare, inherited condition that damages nerve cells. Krabbe disease typically causes worsening signs and symptoms starting in infancy.

Kyphosis

This exaggerated, forward rounding of the back is often caused by osteoporosis in older women. Spinal malformations can cause kyphosis in infants or teens.

Lactose intolerance

Not being able to fully digest the sugar (lactose) in milk can lead to diarrhea, gas and bloating after eating or drinking dairy products.

Laryngitis

Learn about the symptoms, causes and treatment for this common irritation of the voice box.

Latex allergy

Latex allergy is a reaction to proteins in natural rubber latex — found in medical gloves, balloons and more.

Lazy eye (amblyopia)

Abnormal visual development early in life can cause reduced vision in one eye, which often wanders inward or outward.

Lead poisoning

Learn about lead poisoning symptoms and treatment of lead exposure in children and adults. Explore ways to keep your kids safe from lead exposure.

Left ventricular hypertrophy

Learn more about this heart condition that causes the walls of your heart's main pumping chamber to become enlarged and thickened.

Legg-Calve-Perthes disease

This childhood condition occurs when blood supply is temporarily interrupted to the ball part of the hip joint, making it fracture easily and heal poorly.

Legionnaires' disease

Bacteria that can live in water from air conditioning systems, showers and spas cause this severe form of pneumonia.

Leiomyosarcoma

Learn about this rare cancer that begins in smooth muscle tissue. Leiomyosarcoma treatments include surgery, radiation therapy and chemotherapy.

Leukemia

Learn about this cancer that forms in the blood and bone marrow.

Leukoplakia

Leukoplakia appears as thickened, white patches on your gums, cheeks and bottom of your mouth that can't be scraped off.

Lewy body dementia

This common dementia is caused by a buildup of proteins in the brain, and it affects thinking, memory and motor control.

Lice

Learn how to get rid of these tiny, wingless, parasitic insects and keep them from coming back.

Lichen nitidus

Lichen nitidus — Comprehensive overview covers symptoms, treatment of this harmless skin condition.

Lichen planus

Learn about the causes, symptoms and treatment of this skin condition that causes swelling and irritation in the skin, hair, nails, mouth and vagina.

Lichen sclerosus

Learn more about the causes, symptoms, complications, treatment and self-care tips for this blotchy skin condition that affects the genital and anal areas.

Lip cancer

Lip cancer often appears as a sore on your lip that doesn't heal. Learn about lip cancer treatments, including surgery, radiation and chemotherapy.

Lipoma

Lipoma — Comprehensive overview covers symptoms, causes, treatment of this usually harmless fatty tumor that tends to show up in middle age.

Liposarcoma

Learn about diagnosis and treatment options for this type of soft tissue sarcoma that forms from fat cells.

Listeria infection

This foodborne bacterial illness can be very serious for some people. Learn about symptoms, treatment and tips for prevention.

Liver cancer

Learn how doctors use surgery, liver transplant, radiation, chemotherapy and other methods to treat hepatocellular carcinoma and other types of liver cancer.

Liver disease

The liver has a lot of important functions including ridding the body of toxins. Learn about problems that can affect the liver and how to avoid them.

Liver hemangioma

A liver hemangioma is a noncancerous mass that typically doesn't need treatment. Find out more about this common liver condition and when to get treatment.

Lobular carcinoma in situ (LCIS)

If a breast biopsy reveals you have LCIS, your risk of breast cancer is increased. Learn how you can reduce your risk through medications and other strategies.

Long QT syndrome

Learn more about the causes and treatment of this heart rhythm condition that can potentially cause fast, chaotic heartbeats.

Low blood pressure (hypotension)

Low blood pressure isn't always a concern. But sometimes hypotension can cause dizziness and fainting or be life-threatening. Learn when it's treated.

Low sex drive in women

Many women experience a low sex drive at some point. But you can get your desire back. Learn about the diagnosis and treatment of lost libido in women.

Low sperm count

Having a low sperm count can make conceiving a child difficult, but not necessarily impossible. Learn about possible causes and treatment.

Lung cancer

Learn about the approaches doctors take to treating this deadly form of cancer, including minimally invasive surgery, targeted therapy and immunotherapy.

Lupus

Learn how this disease can affect your joints, skin, kidneys and other areas of your body, along with how to get symptom control.

Lupus nephritis

Learn about this common lupus complication affecting the kidneys, including symptoms to watch for, how it's diagnosed and what treatments are available.

Lyme disease

The most common tick-borne illness in North America and Europe, Lyme disease is caused by the bite of an infected tick.

Lymphedema

Damaged or removed lymph nodes can affect how lymph fluid drains. Fluid buildup leads to swelling. Treatments include compression and massage.

Lymphoma

Cancer that forms in the germ-fighting lymphatic system is called lymphoma. Types of lymphoma include Hodgkin's lymphoma and non-Hodgkin's lymphoma.

Lynch syndrome

Learn about this disorder caused by inherited genetic mutations that increases the risk of colon cancer, endometrial cancer and other forms of cancer.

MCAD deficiency

This inherited genetic disorder prevents the breakdown of certain fats needed for energy, causing dangerously low blood sugar (hypoglycemia) if not treated.

MRSA infection

MRSA infections often occur in health care settings, but they can happen anywhere. Find out about symptoms and treatment for this virulent staph infection.

Malaria

Learn about the symptoms, causes, treatment and prevention of this infectious disease transmitted to humans through mosquito bites.

Male breast cancer

Breast cancer can affect anyone, including men. Learn about the signs and symptoms of this cancer. Treatment most often involves surgery.

Male hypogonadism

This condition affects the ability of men's bodies to produce enough testosterone or enough sperm or both.

Male infertility

Male infertility often plays a role when couples have trouble conceiving. Find out what causes male infertility and available options for treatment.

Malignant hyperthermia

This rare genetic disorder triggers a severe reaction to certain anesthesia drugs, causing rigid muscles, high fever, fast heart rate and rapid breathing.

Malignant peripheral nerve sheath tumors

MPNSTs are cancers that form in the linings of nerves. Treatment includes surgery, radiation therapy and, sometimes, chemotherapy.

Mammary duct ectasia

Mammary duct ectasia is a noncancerous breast condition that affects the milk ducts. Learn the signs and symptoms and when treatment might be needed.

Marfan syndrome

This inherited disorder affects the skeleton and the eyes. It can also harm the large blood vessel that carries blood from the heart to the rest of the body.

Mastitis

Redness, pain and swelling in your breast could be mastitis — inflammation of breast tissue. Find out about mastitis symptoms, treatment and self-care.

Measles

Learn about this vaccine-preventable disease that used to be common in childhood and is well known for a characteristic red, splotchy rash and high fever.

Median arcuate ligament syndrome (MALS)

Stomach pain after eating isn't always indigestion. It could be MALS, also called celiac artery compression. Know the warning signs and symptoms.

Medication overuse headaches

When medications that ease headache pain are used too often, these drugs can actually start causing headaches. Learn about prevention and treatment.

Medulloblastoma

Medulloblastoma is the most common cancerous brain tumor in children. Treatment usually includes a combination of surgery, radiation and chemotherapy.

Melanoma

Learn about melanoma symptoms, such as suspicious moles, and find out about melanoma treatments, including surgery, radiation therapy and immunotherapy.

Membranous nephropathy

Membranous nephropathy is a sometimes silent kidney problem. But it can be serious. Learn the symptoms, treatment and how clinical trials may help.

Meniere's disease

This chronic disorder affects balance and hearing, causing unpredictable episodes of dizziness and hearing problems.

Meningioma

Meningioma is the most common type of tumor that forms in the head and may affect the brain. Find out about meningioma symptoms, diagnosis and treatment.

Meningitis

Spot the signs and understand the treatment options for meningitis, an infection that has several possible causes.

Menopause

Find out about this biological change and its long-term health implications — and learn how to manage bothersome hot flashes and other menopause symptoms.

Menorrhagia (heavy menstrual bleeding)

Learn about the causes and treatment of heavy menstrual periods.

Menstrual cramps

Menstrual cramps — pain in the lower abdomen just before or during menstrual periods — can range from mild to severe. Learn about treatment options.

Mental illness

A wide range of mental health conditions affect mood, thinking and behavior and can make you miserable and cause problems in daily life.

Merkel cell carcinoma

Learn about this aggressive skin cancer. Find out about symptoms, diagnosis and treatments, including Mohs surgery, radiation and immunotherapy.

Mesenteric ischemia

Mesenteric ischemia can come on suddenly or develop over time. Find out more about this condition that restricts blood flow to the small intestine.

Mesenteric lymphadenitis

This painful condition, which involves inflamed lymph nodes in the membrane that connects your bowel to your abdominal wall, usually affects children and teens.

Mesothelioma

Learn about this uncommon cancer that's linked to asbestos exposure. Mesothelioma treatments include surgery, radiation and chemotherapy.

Metabolic syndrome

Having three or more specific risk factors, such as high blood pressure or abdominal fat, boosts your risk of type 2 diabetes and heart disease.

Metachromatic leukodystrophy

This rare genetic disorder causes fatty substances (sulfatides) to build up in your brain and nervous system, causing progressive loss of nerve function.

Metatarsalgia

Metatarsalgia is a condition in which the ball of your foot becomes painful and inflamed. Learn about the causes, treatments and prevention of this injury.

Microcephaly

When an infant's head is smaller than expected, it may be microcephaly — a brain abnormality that often develops in the womb and affects child development.

Microscopic colitis

Persistent, watery diarrhea could be a sign of microscopic colitis. Find out about testing and treatment for this inflammatory disorder of the colon.

Migraine

Find out about painful migraine headaches that can last hours to days. Other symptoms may include nausea, vomiting, and sensitivity to light and sound.

Migraine with aura

Learn more about migraine that causes pain and sensory disturbances (aura), such as flashes of light, blind spots or tingling in your hands or face.

Mild cognitive impairment (MCI)

Learn more about this stage between the normal cognitive decline of aging and the more serious decline of dementia.

Milia

Milia — Comprehensive overview covers symptoms, causes, treatment of this newborn complexion problem.

Milk allergy

Find out what happens when the immune system reacts abnormally to proteins in milk, causing allergic signs and symptoms such as hives and wheezing.

Miscarriage

Learn about miscarriage symptoms, what might cause a miscarriage and how to cope with pregnancy loss.

Mitral valve disease

Learn more about diseases that affect the valve between the left heart chambers, including mitral valve regurgitation and mitral valve stenosis.

Mitral valve prolapse

This heart condition, also called Barlow syndrome, affects the valve separating the left heart chambers. Know the symptoms and when it’s treated.

Mitral valve regurgitation

Learn more about the symptoms and treatment of the most common heart valve condition, which causes blood to leak backward in the heart.

Mitral valve stenosis

Learn about symptoms, causes and treatment of this condition that affects your heart's mitral valve.

Mittelschmerz

Some women experience pain on one side of the lower abdomen midway through their menstrual cycles. This cyclic pelvic pain is known as mittelschmerz.

Mixed connective tissue disease

Mixed connective tissue disease has signs and symptoms of multiple disorders, making it difficult to diagnose. There's no cure, but medications can help.

Molar pregnancy

Molar pregnancy is a rare complication that requires early treatment. Learn more about diagnosis and treatment of this type of pregnancy loss.

Mold allergy

Coughing, sneezing and itchy eyes often accompany this common allergy. Find out how to treat this condition and help keep it under control.

Moles

Learn about moles (nevi), what causes them, whether they put you at increased risk of skin cancer and how to check a mole for signs of skin cancer.

Molluscum contagiosum

Learn how to prevent and treat this common skin infection that affects people of all ages.

Monoclonal gammopathy of undetermined significance (MGUS)

This condition happens when your bone marrow produces an abnormal protein in your blood. It can sometimes progress to certain types of blood cancer.

Mononucleosis

Learn about the symptoms and treatment of the kissing disease in adults and children.

Mood disorders

Specialists in psychiatry and psychology at Mayo Clinic diagnose and treat adults and children with depression, bipolar disorder and other mood disorders.

Morning sickness

Learn more about pregnancy-related nausea and vomiting, along with remedies that may help ease that queasy feeling.

Morphea

Learn more about this rare, painless skin condition, including risk factors, symptoms, complications and treatment.

Morton's neuroma

Learn how this painful foot disorder is diagnosed, as well as its causes and treatment.

Mosquito bites

Mosquito bites — Comprehensive overview covers prevention, treatment and role in disease transmission.

Mouth cancer

Learn what doctors and dentists look for when diagnosing mouth cancer. Find out about oral cancer treatments, including surgery, chemotherapy and radiation.

Moyamoya disease

This rare disorder occurs when blood flow to the brain is blocked or narrowed and a tiny cluster of blood vessels forms at the base of the brain.

Multiple endocrine neoplasia, type 1 (MEN 1)

Learn about diagnosis and treatment for multiple endocrine neoplasia, type 1 (MEN 1) — a rare disorder that causes tumors and overproduction of hormones.

Multiple myeloma

Learn about this cancer that forms from white blood cells called plasma cells. Multiple myeloma treatments include medications and bone marrow transplant.

Multiple sclerosis

This nervous system disorder causes a range of symptoms — and while there's no cure, it's possible to have long periods of remission.

Multiple system atrophy (MSA)

This rare neurological disorder affects the body's involuntary processes such as movement and blood pressure.

Multisystem inflammatory syndrome in children (MIS-C) and COVID-19

Learn about the symptoms of MIS-C, a serious condition linked to coronavirus disease 2019 (COVID-19). Get help fast if your child shows any signs.

Mumps

Find out more about the symptoms and treatment of this viral illness and how vaccination prevents it.

Muscle cramp

Muscle cramp — Comprehensive overview covers causes, treatment, prevention of cramped muscles.

Muscle strains

Minor strains may only overstretch a muscle or tendon, while more severe injuries may involve partial or complete tears in these tissues.

Muscular dystrophy

Read about different types of this progressive disease that interferes with the creation of new muscle, as well as treatments to help with symptoms.

Myasthenia gravis

A breakdown in the communication between nerves and muscles causes weakness and fatigue of muscles under your voluntary control.

Myelodysplastic syndromes

Learn how medications and bone marrow transplants are used to control complications caused by these syndromes that affect the bone marrow.

Myelofibrosis

Find out more about this bone marrow cancer. Learn about symptoms, diagnosis and treatments for primary myelofibrosis and secondary myelofibrosis.

Myocardial ischemia

Myocardial ischemia reduces blood flow to the heart and may cause chest pain – but not always. Learn all the signs and symptoms and how to treat it.

Myocarditis

Learn about the diagnosis and treatment of this inflammation of the heart muscle that can reduce the heart's ability to pump blood.

Myoclonus

These uncontrollable jerking motions, which include normal hiccups and "sleep starts," can be disabling when caused by an underlying health condition.

Myofascial pain syndrome

In this condition, pressure on trigger points can cause persistent pain in the muscle itself and sometimes in seemingly unrelated parts of your body.

Myxofibrosarcoma

Learn about this connective tissue cancer that often starts in the arms and legs. MFS treatments include surgery, radiation therapy and chemotherapy.

Naegleria infection

Naegleria infection is caused by an amoeba most often found in warm, fresh water. Learn what symptoms to look for in this rare, often fatal infection.

Nail fungus

Learn about symptoms, treatment and prevention of this common infection among older adults that causes nails to discolor and crumble.

Narcissistic personality disorder

This mental health disorder includes an inflated sense of importance, a deep need for excessive admiration, fragile self-esteem and troubled relationships.

Narcolepsy

Learn more about this sleep disorder that causes periods of involuntary sleep, sleep paralysis and early rapid eye movement (REM) sleep.

Nasal and paranasal tumors

Learn about these cancerous and noncancerous growths that form in and around the nose. Treatments include surgery, radiation and chemotherapy.

Nasal polyps

Nasal polyps are painless, noncancerous growths that can lead to a lost sense of smell or infection. Medication or surgery can help.

Nasopharyngeal carcinoma

Nasopharyngeal carcinoma is cancer that occurs in the nasopharynx, which is located behind your nose and above the back of your throat.

Nearsightedness

Tired of squinting at objects in the distance? There are many effective treatment options for nearsightedness, and some preventive options emerging.

Neck pain

Neck pain — Comprehensive overview covers causes of neck pain and neck pain relief options.

Nephrogenic systemic fibrosis

Learn about symptoms, risk factors and possible treatments for this rare disorder in people with advanced kidney disease.

Nephrotic syndrome

Swelling around your feet and ankles is a common sign of this condition that occurs when your kidneys pass too much protein in your urine.

Neuroblastoma

Learn more about the symptoms, diagnosis and treatment of neuroblastoma, one of the most common cancers of childhood.

Neurodermatitis

Learn more about this itchy skin condition that can disrupt your sleep and daily activities. Successful treatment depends on resisting the urge to scratch.

Neuroendocrine tumors

Learn about the types of tumors that make up this group of rare cancers. Find out about symptoms, causes, diagnosis and treatments.

Neurofibroma

Neurofibroma is a noncancerous nerve tumor that can appear anywhere in the body, forming soft bumps on or under the skin. Treatment may involve surgery.

Neurofibromatosis

This genetic disorder causes tumors on nerve tissue, but surgery and other therapies can manage pain and other symptoms.

Neuromyelitis optica

Understand more about this condition that affects the spinal cord and eye nerves and is sometimes mistaken for multiple sclerosis.

Nickel allergy

Nickel allergy, often caused by nickel in jewelry, is a form of contact dermatitis. Things such as coins and zippers also may provoke nickel allergy.

Nicotine dependence

Nicotine dependence can be tough to kick, but treatments and resources are available to boost your chances of success.

Niemann-Pick

Niemann-Pick — Learn more about this inherited disease that mainly affects children, causing malfunction of the nerves, brain and other organs.

Nightmare disorder

Nightmare disorder involves disturbing or scary dreams that awaken you, causing distress or preventing adequate sleep.

Non-Hodgkin's lymphoma

Learn more about the symptoms, risk factors and treatment of this cancer of the lymphatic system that causes swollen lymph nodes.

Nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease is becoming more common in the Western world. Find out how to treat and prevent this potentially dangerous liver disease.

Nonallergic rhinitis

A number of factors can trigger this bothersome nonallergic condition. Learn how to get relief from your runny, stuffy nose.

Nonmelanoma skin cancer

Learn about treatment options for all types of nonmelanoma skin cancer, including squamous cell carcinoma, basal cell carcinoma and others.

Noonan syndrome

Noonan syndrome is a genetic disorder that may cause unusual facial features, short stature, heart defects, eye conditions and other health problems.

Norovirus infection

This highly contagious virus spreads through contaminated food, water or surfaces and causes vomiting and diarrhea. Learn ways to protect yourself.

Obesity

Obesity isn't just a cosmetic concern. It is a medical problem that increases the risk of heart disease, diabetes and certain cancers.

Obsessive-compulsive disorder (OCD)

OCD features a pattern of unwanted thoughts and fears (obsessions), leading to repetitive behaviors (compulsions) that interfere with daily activities.

Obstructive sleep apnea

Learn the signs that point to this common and potentially serious sleep disorder and find out the treatments that can help you sleep better.

Occupational asthma

Dust, fumes and other substances you come into contact with at work can cause asthma. Find out how to recognize this common type of asthma.

Ocular rosacea

Learn about symptoms, causes and treatments of ocular rosacea — an eye condition that often affects people who have skin rosacea.

Oligodendroglioma

Learn about this type of tumor that can occur in the brain or spinal cord.

Oppositional defiant disorder (ODD)

ODD is a childhood mental health disorder that includes frequent and persistent anger, irritability, arguing, defiance or vindictiveness toward authority.

Optic neuritis

Learn about this painful eye disorder that affects your optic nerve and what your doctor may recommend for treatment.

Oral lichen planus

This chronic inflammatory condition results in white, lacy patches; red, swollen tissues; or open sores inside your mouth that may cause burning or pain.

Oral thrush

Oral thrush is a fungal infection caused by the overgrowth of Candida albicans, which causes creamy white lesions on the tongue and lining of your mouth.

Orchitis

This inflammation of one or both testicles can cause pain and infertility. It's usually caused by a bacterial infection or the mumps virus.

Orthostatic hypotension (postural hypotension)

If you have this form of low blood pressure, you might feel dizzy or lightheaded or you might faint when you rise from sitting or lying down.

Osteoarthritis

This most common form of arthritis mainly affects joints in your hands, knees, hips and spine. There's no cure, but symptoms can be managed.

Osteochondritis dissecans

Osteochondritis dissecans most commonly affects children who are very active in sports. Learn about the symptoms and treatment of this joint condition.

Osteomyelitis

Bones don't easily get infected, but certain situations, such as a serious injury, bloodstream infection or surgery, may lead to a bone infection.

Osteoporosis

Fractures associated with this bone-weakening condition can be life-altering. Good nutrition, regular exercise and medications can help.

Osteosarcoma

Learn about the symptoms and causes of this bone cancer that occurs most often in children. Find out about treatments, including limb-sparing operations.

Ovarian cancer

Learn more about cancer of the ovaries, including symptoms and treatments, such as surgery, chemotherapy and targeted therapy.

Ovarian cysts

Many women have ovarian cysts at some time. Most are harmless, but some can cause serious symptoms. Know what symptoms to watch for.

Ovarian hyperstimulation syndrome

Learn about this possible complication of fertility treatments and how to recognize when you need to contact your care team.

Overactive bladder

Learn how you can get relief for frequent, sudden urges to urinate, which may point to overactive bladder or urinary incontinence.

Paget's disease of bone

Find out about this condition that can make bones fragile and misshapen, along with the osteoporosis drugs that can treat it.

Paget's disease of the breast

This rare form of breast cancer causes breast skin changes. Learn about the symptoms, causes, diagnosis and treatments, including surgery.

Painful intercourse (dyspareunia)

Painful intercourse can occur in women for various reasons, ranging from physical problems to emotional concerns. Medications or other therapies may help.

Pancreatic cancer

Learn about symptoms, risk factors, prevention, diagnosis, surgery, chemotherapy and other treatment for this serious condition affecting the pancreas.

Pancreatic cysts

Most pancreatic cysts are benign, but some types are cancerous. Find out about symptoms, causes and treatment of cysts in the pancreas.

Pancreatic neuroendocrine tumors

Learn about these cancers that start in the hormone-producing cells of the pancreas. Explore innovative treatments, including the Whipple procedure and PRRT.

Pancreatitis

Pancreatitis can occur suddenly or build up over time. Learn about symptoms, causes and treatment of this potentially serious digestive system disorder.

Panic attacks and panic disorder

Learn about effective treatment for sudden episodes of intense fear that trigger severe physical reactions when there is no real danger or apparent cause.

Paraganglioma

Learn about this rare tumor that begins in nerve cells and sometimes causes high blood pressure. It's usually benign but sometimes spreads.

Paraneoplastic syndromes of the nervous system

This group of uncommon disorders affects people who have cancer, and occurs when parts of the immune system attack parts of the nervous system.

Parkinson's disease

There's no cure for this progressive movement disorder, but treatments can help significantly improve your symptoms.

Parotid tumors

Learn about parotid tumor symptoms and diagnosis. Find out how doctors use operations, such as parotidectomy, to treat parotid tumors.

Partial anomalous pulmonary venous return

In this congenital heart defect, some of the lung blood vessels connect to the wrong places in the heart. Learn more about the causes, symptoms and treatment.

Parvovirus infection

Learn more about the symptoms, causes, treatment and prevention of this common childhood infection — sometimes called slapped-cheek disease.

Patellar tendinitis

Jumper's knee — a common knee injury — affects the tendon that stretches from the kneecap (patella) to the shinbone.

Patellofemoral pain syndrome

Patellofemoral pain syndrome — Comprehensive overview covers symptoms, treatment of this knee condition common among runners.

Patent ductus arteriosus (PDA)

Learn about symptoms, causes and treatment of patent ductus arteriosus, a common — and treatable — heart defect that occurs shortly after birth.

Patent foramen ovale

Learn more about the causes and complications of this condition in which a hole in the heart doesn't close the way it should after birth.

Peanut allergy

Peanut allergy can be serious. Find out what you need to know to prevent a life-threatening reaction, and get the latest on treatment approaches.

Pectus excavatum

Pectus excavatum causes the breastbone to sink into the chest. This can affect heart and lung function. Surgery helps correct the deformity.

Pediatric brain tumors

Pediatric brain tumors include medulloblastoma, glioma, embryonal tumor, germ cell brain tumor, spinal cord tumor, craniopharyngioma and pineoblastoma.

Pediatric obstructive sleep apnea

If your child's breathing becomes repeatedly blocked during sleep — either partially or completely — pediatric obstructive sleep apnea could be the cause.

Pelvic inflammatory disease (PID)

This serious infection of the female reproductive organs can cause long-term complications such as infertility and chronic pain. Know the symptoms and causes.

Pemphigus

Learn about symptoms, causes, treatment and self-care tips for this group of rare conditions that causes blisters and sores on the skin or mucous membranes.

Penicillin allergy

Understand the importance of an accurate diagnosis for penicillin allergy and the best practices for antibiotic treatment options.

Peptic ulcer

Feeling a dull or burning pain in your stomach? It could be a peptic ulcer — a common, treatable digestive condition. Find out more.

Pericardial effusion

Learn the symptoms, causes and treatment of excess fluid around the heart.

Pericarditis

Inflammation of the tissue surrounding the heart can cause symptoms similar to other heart conditions. Know how pericarditis is diagnosed and treated.

Perimenopause

Discover effective treatments and learn self-care strategies for hot flashes, night sweats, vaginal dryness and other perimenopause symptoms.

Periodontitis

This serious gum infection damages the soft tissue and can destroy the bone that supports your teeth. It can cause teeth to loosen or lead to tooth loss.

Peripheral artery disease (PAD)

Learn more about this common circulatory condition, often first signaled by leg pain when walking. Lifestyle changes and medications can help.

Peripheral nerve injuries

These types of injuries affect the nerves that link the brain and spinal cord to nerves in other parts of the body.

Peripheral nerve tumors

Learn more about growths that form on nerves connecting to the spinal cord. Surgery is the most common nerve tumor treatment.

Peripheral neuropathy

Learn what may cause the prickling, tingling or numb sensations of nerve damage and how to prevent and treat this painful disorder.

Peritonitis

Peritonitis — Comprehensive overview covers causes, symptoms, treatment of this abdominal infection.

Persistent depressive disorder (dysthymia)

Also called dysthymia, this chronic form of depression may cause you to lose interest in life, feel hopeless, lack productivity and have low self-esteem.

Persistent post-concussive symptoms (Post-concussion syndrome)

Find out what to do when symptoms such as headache, fatigue and dizziness last longer than expected after the injury that caused the concussion.

Personality disorders

A personality disorder is a mental disorder involving a rigid and unhealthy pattern of thinking, functioning and behaving.

Pet allergy

Family pet making you sneeze? Find out about diagnosis, treatment and handy household tips for relieving bothersome pet allergy symptoms.

Peyronie's disease

Understand what causes bent and painful erections, and learn what treatments are available.

Phantom pain

Read about this puzzling condition that causes people to feel pain where a part of the body has been amputated. A number of treatments are available.

Phenylketonuria (PKU)

PKU is caused by a change in the gene that helps create an enzyme needed to break down phenylalanine. Treatment includes a special diet and medication.

Pheochromocytoma

Find out more about the symptoms, causes and treatment of this rare adrenal gland tumor that is usually noncancerous.

Pilonidal cyst

Pilonidal cyst — Comprehensive overview covers causes, symptoms and treatments of this skin abnormality.

Pinched nerve

Pressure on a nerve can lead to numbness, tingling or pain that’s often improved by resting the area.

Pineoblastoma

Learn about this rare cancer that begins in the brain's pineal gland. Pineoblastoma treatments include surgery, radiation therapy and chemotherapy.

Pink eye (conjunctivitis)

Pink eye (conjunctivitis) is uncomfortable and contagious, but — like the common cold — rarely requires medication or staying home.

Pinworm infection

Learn more about the symptoms, treatment and prevention of this common type of intestinal worm infection.

Pituitary tumors

Learn more about the symptoms, causes and treatment of these abnormal growths that develop in your pituitary gland.

Pityriasis rosea

Pityriasis rosea — Comprehensive overview covers symptoms, causes and treatment of this common skin condition.

Placenta accreta

During pregnancy, if part of the placenta grows too far into the uterine wall, it can remain attached after childbirth, causing severe maternal blood loss.

Placenta previa

Learn about how this pregnancy complication is diagnosed and managed to reduce risks to your baby's health and your own.

Placental abruption

This uncommon pregnancy complication, in which the placenta separates from the wall of the uterus, can endanger both the mother and the baby.

Plague

Learn about the symptoms, risk factors, and treatment of this extremely rare, potentially fatal infectious disease transmitted by fleas and rodents.

Plantar fasciitis

Learn about this most common cause of stabbing heel pain.

Plantar warts

Learn about the causes, treatment and prevention of these hard, sometimes painful growths that appear on the heel or ball of the foot.

Pleurisy

In this condition, the tissues that line the lungs and chest cavity (pleura) become inflamed, causing sharp chest pain that worsens during breathing.

Pneumonia

Pneumonia — Learn about the symptoms, causes and treatment of this serious lung infection.

Pneumonitis

Pneumonitis is a general term for lung inflammation. It can cause difficulty breathing and is often accompanied by a cough.

Pneumothorax

A collapsed lung occurs when air leaks into the space between your lung and chest wall. This air pushes on the outside of your lung and makes it collapse.

Poison ivy rash

Learn about the symptoms, causes and home remedies for this itchy skin rash and how to prevent it.

Polio

Learn more about this contagious viral illness that in its most severe form causes nerve injury leading to paralysis, difficulty breathing and sometimes death.

Polycystic kidney disease

Learn how treatments and lifestyle changes might help reduce damage to your kidneys from polycystic kidney disease.

Polycystic ovary syndrome (PCOS)

Polycystic ovaries, hormone imbalance and irregular periods are telltale signs and symptoms of PCOS. Find out about PCOS treatments.

Polycythemia vera

This slow-growing blood cancer mainly affects people over 60. Treatments and lifestyle changes may reduce complications and ease symptoms.

Polyhydramnios

Learn about symptoms, causes and treatment for polyhydramnios — excessive accumulation of amniotic fluid during pregnancy.

Polymorphous light eruption

Learn more about the symptoms and treatments for this sun-induced skin rash that usually appears in spring or summer, and also after using tanning beds.

Polymyalgia rheumatica

Older adults who suddenly develop muscle pain and stiffness, especially in the shoulders, might have polymyalgia rheumatica.

Polymyositis

The muscle weakness associated with polymyositis can make it difficult to climb stairs or reach overhead. Breathing and swallowing also can be affected.

Popliteal artery entrapment syndrome

Calf pain cramping your style during a workout? Know the signs and symptoms of popliteal artery entrapment syndrome.

Porphyria

Porphyria is a group of disorders that result from a buildup of porphyrin in your body, affecting your nervous system, skin and other organs.

Post-polio syndrome

This syndrome causes a number of potentially serious symptoms that appear decades after the polio virus.

Post-traumatic stress disorder (PTSD)

Post-traumatic stress disorder (PTSD) is a mental health condition triggered by a terrifying event, causing flashbacks, nightmares and severe anxiety.

Post-vasectomy pain syndrome

Learn about post-vasectomy pain syndrome (PVPS) — How it happens after a vasectomy, tests to diagnose it and treatment options.

Posterior cortical atrophy

This rare neurological syndrome that's often caused by Alzheimer's disease affects vision and coordination.

Posterior vaginal prolapse (rectocele)

Learn about symptoms and possible treatments for this pelvic floor disorder where the rectum presses against weak tissues, bulging into the vagina.

Postherpetic neuralgia

This complication of shingles can cause pain, itching and numbness long after the shingles rash clears. Treatments can ease symptoms.

Postpartum depression

Learn the risk factors and symptoms of depression in new mothers, as well as effective treatment that can help you manage symptoms and bond with your baby.

Postpartum preeclampsia

Learn about this rare condition that's typically associated with pregnancy, but that can occur after delivery, too. Untreated, it can lead to serious complications.

Prader-Willi syndrome

Prader-Willi syndrome is a rare genetic disorder that results in physical, mental and behavioral problems, including a constant sense of hunger.

Precocious puberty

Read about the signs and symptoms, causes, and risk factors that may cause a child's body to begin changing into an adult's body too soon.

Prediabetes

Blood sugar levels start to rise even before you get type 2 diabetes. Find out what steps you can take to prevent diabetes from developing.

Preeclampsia

Learn about the diagnosis, treatment of this pregnancy complication of high blood pressure with related damage to the kidneys or other organs.

Premature birth

Having a preemie can be overwhelming. Here's what you need to know about your baby's care and the possible complications of a premature birth.

Premature ejaculation

Understand what causes premature ejaculation, as well as how to treat it and prevent it.

Premature ventricular contractions (PVCs)

Premature ventricular contractions (PVCs) are extra heartbeats that disrupt the heart rhythm. PVCs are common.

Premenstrual syndrome (PMS)

Mood swings, cramps and irritability are just a few telltale clues that you're getting your period. Learn what you can do for PMS symptom relief.

Presbyopia

Have you noticed — yet — having to hold books at arm's length to read them? Find out what options are available when it happens.

Prescription drug abuse

Using a prescription medication in a way not intended by the doctor can lead to drug abuse. Learn about risk factors and treatment for drug misuse.

Preterm labor

Going into labor before your due date is serious, but knowing the risk factors and how to manage them can help.

Priapism

Understand the symptoms, possible causes and treatment of prolonged erection of the penis, including when to seek emergency care.

Primary biliary cholangitis

Primary biliary cholangitis is a type of liver disease that damages the bile ducts. Early treatment may help prevent liver failure.

Primary immunodeficiency

Frequent infections could mean you have an immune system disorder. The conditions in this category are usually caused by genetic changes.

Primary lateral sclerosis (PLS)

This motor neuron disease causes nerves within the brain to slowly break down, resulting in muscle weakness primarily in the legs, arms and tongue.

Primary ovarian insufficiency

Primary ovarian insufficiency, also called premature ovarian failure, occurs in women under age 40. Hormone therapy can lessen uncomfortable symptoms.

Primary progressive aphasia

Find out more about this type of dementia that affects the speech and language areas of the brain.

Primary sclerosing cholangitis

Liver damage can result from this potentially serious disease in which scarring blocks the bile ducts. A liver transplant is the only known cure.

Proctitis

Proctitis means inflammation of the rectal lining. This condition is often a treatment side effect or part of a more generalized disease.

Progeria

Progeria is an extremely rare, progressive genetic disorder that causes children to age rapidly, beginning in their first two years of life.

Progressive supranuclear palsy

Learn about this brain disorder that interferes with the ability to walk, move your eyes, talk and eat.

Prolactinoma

Learn how this pituitary gland tumor alters certain hormone levels and leads to problems such as infertility, decreased libido and vision problems.

Prostate cancer

Learn about detection, diagnostic approaches, treatment options and advances for prostate cancer, including robotic prostatectomy and current research.

Prostatitis

Learn about tests and treatments for disorders of the prostate gland that cause pain, difficult or painful urination, and other symptoms.

Pseudobulbar affect

Pseudobulbar affect — Overview covers symptoms, treatment of this neurological condition that's characterized by uncontrollable laughing and crying.

Pseudocholinesterase deficiency

This causes sensitivity to certain muscle relaxants used during anesthesia. Muscles may stay relaxed for too long, interfering with movement and breathing.

Pseudogout

Pseudogout — Comprehensive overview covers symptoms, treatment, prevention of this disease that mimics gout.

Pseudomembranous colitis

This inflammatory colon condition is usually caused by the bacterium C. difficile. The use of high-dose antibiotics may let these germs grow unchecked.

Pseudotumor cerebri (idiopathic intracranial hypertension)

Headaches and vision loss can result from this increased pressure inside your brain that occurs with no obvious reason.

Psoriasis

Learn about this common skin condition that causes red, scaly, itchy patches and how you can combine medications with self-care habits to manage it.

Psoriatic arthritis

This form of arthritis affects some people who have psoriasis — a disease that features red patches of skin topped with silvery scales.

Pubic lice (crabs)

Pubic lice (crabs) are an itchy, but treatable, nuisance. Find out how to spot and treat this common sexually transmitted infection (STI).

Pulmonary atresia

Learn more about this life-threatening congenital heart condition that changes the way blood travels from the heart to the rest of the body.

Pulmonary atresia with intact ventricular septum

Also called PA/IVS, this rare congenital heart defect is diagnosed at or shortly after birth. Learn how it may be treated with one or more procedures.

Pulmonary atresia with ventricular septal defect

This congenital heart defect affects the valve between the heart and lungs and includes a hole in the heart. Learn more about the surgeries and procedures needed to treat it.

Pulmonary edema

Get more information about what causes this potentially life-threatening lung condition, and learn how to treat and prevent it.

Pulmonary embolism

Pulmonary embolism is often caused by blood clots that travel to the lungs from the legs. Prevention is aimed at stopping clots from forming in the legs.

Pulmonary fibrosis

Pulmonary fibrosis — Learn about the symptoms, causes and treatment of this serious lung disease that occurs when lung tissue becomes damaged and scarred.

Pulmonary hypertension

Learn more about the warning signs and symptoms and treatment of high blood pressure in the lungs.

Pulmonary valve stenosis

When the valve between the heart and lungs is narrowed, blood flow slows. Know the symptoms of this type of valve disease and how it's treated.

Pyloric stenosis

In this condition, a valve between an infant's stomach and small intestine fails to open enough for food to pass through. Surgery is the treatment.

Pyoderma gangrenosum

Learn about the symptoms, treatment and risk factors of this skin condition with open sores, along with advice on how to cope with it.

Q fever

Learn more about the symptoms, treatment and prevention of this often mild bacterial infection spread by animals.

REM sleep behavior disorder

REM sleep behavior disorder is a sleep disorder in which you physically and vocally act out vivid, often unpleasant dreams during REM sleep.

Rabies

Learn about this deadly virus that most often spreads to people through the bite of an infected animal.

Radiation enteritis

This complication of radiation therapy for cancer can cause stomach pain, vomiting or diarrhea. For most people, symptoms go away within weeks.

Radiation sickness

Read about what happens when someone is exposed to high doses of radiation, and what you can do to prevent such exposure in an emergency.

Ramsay Hunt syndrome

A shingles outbreak can affect the facial nerve near one of your ears, potentially causing facial paralysis and hearing loss.

Raynaud's disease

Learn how this disease causes parts of your body, mainly fingers and toes, to numb, chill and possibly turn colors from cold temperatures or stress.

Reactive arthritis

This joint pain is triggered by an infection in another part of the body — often the intestines, genitals or urinary tract.

Reactive attachment disorder

Reactive attachment disorder is when an infant or young child doesn't establish healthy attachments with parents or caregivers due to neglect.

Rectal cancer

Find out about rectal cancer symptoms, causes and prevention. Learn about treatments, including chemotherapy, radiation and surgery.

Rectal prolapse

It's unclear what exactly causes this rare condition in which the rectum slips outside of the anus. Find out about symptoms and treatment.

Rectovaginal fistula

An abnormal connection between the rectum and vagina allows gas or stool to pass into the vagina. Learn about fistula treatment and self-care.

Recurrent breast cancer

Learn about symptoms that alert doctors to a breast cancer recurrence and strategies for treating cancer that comes back after initial treatment.

Renal artery stenosis

Read more about what happens when the arteries leading to your kidneys become narrowed, as well as potential treatments for this condition.

Residual limb pain

This common pain in the part of a limb that remains after an amputation has many causes and effective treatment options.

Respiratory syncytial virus (RSV)

This common illness affects the lungs. It can seem like a cold, but may be severe, especially in children. Know the symptoms and treatment.

Restless legs syndrome

Uncomfortable sensations in your legs can interrupt your sleep — making you drag through your day. These therapies calm the restlessness and improve sleep.

Retinal detachment

Eye floaters and reduced vision are signs of possible retinal detachment. Find out about causes and treatment for this eye emergency.

Retinal diseases

Learn about the symptoms, diagnosis and treatment for various conditions that affect the retinas and vision. Find out when it's time to contact a doctor.

Retinoblastoma

Learn about the symptoms, causes and treatments for this eye cancer that occurs in young children.

Retractile testicle

Find out about this condition that allows the testicle to move between the scrotum and groin.

Retrograde ejaculation

Learn about the symptoms and treatment options for this condition that can cause male infertility.

Rett syndrome

This rare genetic disorder affects the way the brain develops, causing a progressive inability to use muscles for eye and body movements and language.

Reye's syndrome

Learn more about the causes and treatment of Reye's syndrome, a rare but serious condition causing swelling in the liver and brain.

Rhabdomyosarcoma

RMS, a rare soft tissue cancer, affects children more often than adults. Treatment may include surgery, chemotherapy and radiation therapy.

Rheumatic fever

Learn about this serious complication of strep throat and scarlet fever and what you can do to prevent it.

Rheumatoid arthritis

This chronic inflammatory disorder can affect more than just your joints. It can also damage your skin, eyes, lungs, heart and blood vessels.

Rickets

Learn what can cause this bone-softening disease in children and how supplements may prevent or treat the condition.

Ringworm (body)

Learn more on causes, symptoms, treatments of this easily spread fungal skin infection that itches and is related to athlete's foot.

Ringworm (scalp)

Learn more on causes, symptoms, treatments of this easily spread, itchy fungal skin infection and how to prevent it.

Rocky Mountain spotted fever

Recognize Rocky Mountain spotted fever early to get prompt and potentially lifesaving treatment.

Rosacea

Learn more about this common facial skin condition, including symptoms, triggers, good skin care and medications to treat it.

Roseola

Learn about the symptoms, causes and treatment of this common childhood infection and rash caused by two strains of herpes virus.

Rotator cuff injury

This common shoulder disorder is often caused by repetitive overhead motions in jobs or sports. Extensive rotator cuff tears may require surgery.

Rotavirus

Learn more about this common childhood condition that causes fever, vomiting, diarrhea and sometimes abdominal pain.

Rubella

Learn more about the symptoms and prevention of this contagious viral infection best known for its distinctive red rash.

Rumination syndrome

Learn about this condition that results in repetitive regurgitation and reswallowing meals. Behavioral therapy and medication are treatments.

Ruptured eardrum (perforated eardrum)

A ruptured eardrum is a hole or tear in your eardrum, the thin tissue that separates your ear canal from your middle ear.

Ruptured spleen

A break in the surface of your spleen, usually from a forceful blow to your abdomen, can cause life-threatening internal bleeding.

Sacral dimple

Sacral dimple — Comprehensive overview covers complications, treatment of this indentation on the lower back.

Sacroiliitis

Sacroiliitis — Comprehensive overview covers symptoms, causes, diagnosis, treatment of inflammation of the sacroiliac joints.

Salivary gland tumors

Learn about this rare tumor that forms in the salivary glands. Treatments include surgery and radiation therapy.

Salmonella infection

This common bacterial infection is spread through contaminated food or water and affects the intestinal tract. Learn more about prevention and treatment.

Sarcoidosis

This inflammatory disease results in growth of tiny granulomas in different parts of the body, including the lungs, eyes, skin and heart.

Sarcoma

Learn about this cancer that forms in the bones and the connective tissue. Find out about symptoms, diagnosis, treatment and the many types of sarcoma.

Scabies

Learn more about this infectious condition that causes intense itching, usually in areas where the skin folds, such as around joints.

Scarlet fever

Learn more about the symptoms, causes, complications and treatment of this strep-related bacterial infection.

Schizoaffective disorder

This mental health disorder includes schizophrenia symptoms, such as delusions or hallucinations, and mood disorder symptoms, such as depression or mania.

Schizoid personality disorder

Schizoid personality disorder is an uncommon condition in which people consistently shy away from interaction with others and have a limited range of emotional expression.

Schizophrenia

This severe mental disorder can result in hallucinations, delusions, and extremely disordered thinking and behavior that interfere with daily living.

Schizotypal personality disorder

This personality disorder may include odd or eccentric thinking and behavior, few ― if any ― close relationships, and a significant distrust of others.

Schwannoma

Learn about the diagnosis and treatment of this usually benign, slow-growing tumor that begins in peripheral nerve cells.

Sciatica

Sciatica — Comprehensive overview covers symptoms, treatment of this acute back, pelvic and leg pain.

Scleroderma

This group of rare diseases involves the hardening and tightening of the skin and connective tissues. Some forms can affect internal organs.

Sclerosing mesenteritis

In sclerosing mesenteritis, tissue in the abdomen becomes inflamed and scarred. Learn about symptoms, diagnosis and treatment for this rare condition.

Scoliosis

This sideways curvature of the spine occurs most often during the growth spurt just before puberty. Treatment may include braces or surgery.

Scorpion sting

Learn more about symptoms, risk factors, treatment and prevention of this type of sting, which is painful but rarely life-threatening.

Scrotal masses

Scrotal masses have many underlying causes. Even painless scrotal masses should be evaluated promptly by a doctor.

Seasonal affective disorder (SAD)

This type of depression is related to changes in seasons and begins and ends at about the same times every year.

Sebaceous carcinoma

Learn about diagnosis and treatments for this rare cancer that often affects the eyelid. Treatments include Mohs surgery and radiation.

Seborrheic dermatitis

Find out what you can do to treat this flaky skin condition that can cause scaly skin and stubborn, itchy dandruff.

Seborrheic keratosis

Learn more about the symptoms and treatments of this common, noncancerous skin growth that gradually appears as you age.

Secondary hypertension

Learn more about high blood pressure that's caused by another medical condition. Find out about risk factors and treatments to help you stay healthy.

Seizures

Learn about seizure types, what causes seizures, what happens during a seizure and what you can do if you see someone having a seizure.

Self-injury/cutting

Deliberately hurting your own body, such as cutting or burning, is a harmful way to cope with emotional pain, intense anger and frustration.

Separation anxiety disorder

Intense or prolonged separation anxiety that interferes with school or other daily activities or includes panic attacks. Learn about treatment.

Sepsis

Learn more about the symptoms and treatment of sepsis, a serious infection-related illness.

Septic arthritis

Learn about this painful infection in a joint and why prompt treatment can help minimize joint damage.

Serotonin syndrome

Learn how certain drug interactions or an increase in the dose of certain drugs can cause serotonin levels to rise to potentially dangerous levels.

Severe acute respiratory syndrome (SARS)

Learn about this contagious and sometimes fatal respiratory illness. The last known infection was reported in 2004.

Sex headaches

Learn about the causes and treatment of this type of headache.

Sexually transmitted diseases (STDs)

Find out the signs and symptoms of STDs and what you can do to prevent them, along with the treatments available if you're diagnosed with one.

Shaken baby syndrome

Understand why shaking a baby can cause brain damage, and why getting immediate medical care can save a child’s life or prevent serious health problems.

Shellfish allergy

It's possible to be allergic to some types of shellfish without reacting to other types. Learn more about this common food allergy.

Shigella infection

Shigella infection is an intestinal infection that causes diarrhea. Learn how to recognize, treat and prevent the spread of this contagious condition.

Shin splints

Shin splints are common in runners, dancers and military recruits. Learn how modifying your exercise routine can help prevent shin splints from recurring.

Shingles

Learn more about the symptoms, causes, treatment and vaccine prevention of this painful condition affecting the nerves.

Short bowel syndrome

Short bowel syndrome occurs when part of the small intestine is missing, either at birth or after surgery. The syndrome keeps you from absorbing needed nutrients.

Sick sinus syndrome

This heart rhythm disorder causes slow, paused or irregular heartbeats. Learn the symptoms and how it's treated.

Sickle cell anemia

Learn about the symptoms, causes and treatment of this inherited blood disorder that, in the United States, is more common among Black people.

Sinus headaches

Sinus headaches are often to blame for headache with facial pain — but that pain might actually be a migraine.

Sjogren's syndrome

If you're bothered by dry eyes and mouth, talk to your doctor about whether you have the autoimmune condition Sjogren's syndrome.

Skin cancer

Learn about skin cancer, including basal cell carcinoma, melanoma and squamous cell carcinoma. Find out about symptoms, treatments and ways to lower your risk.

Sleep apnea

Snoring loudly could be an indication of sleep apnea, a disorder in which breathing stops and starts repeatedly during sleep.

Sleep terrors (night terrors)

Sleep terrors (night terrors) are episodes of screaming, intense fear and flailing while still asleep.

Sleepwalking

Comprehensive overview covers causes, treatment and prevention of this usually harmless sleep disorder.

Small bowel cancer

Small bowel cancer starts in the small intestine. Find out more about symptoms and treatments, including surgery, chemotherapy and targeted therapy.

Small bowel prolapse (enterocele)

Learn more about this condition also called a vaginal hernia that happens when the small bowel pushes down onto the top of the vagina.

Small intestinal bacterial overgrowth (SIBO)

Small intestinal bacterial overgrowth (SIBO) can occur when excess bacteria builds up in the small intestine. Learn more about this bowel disorder.

Small vessel disease

Also called coronary microvascular disease, this type of heart disease can be hard to detect. Know the symptoms and how it's diagnosed and treated.

Smallpox

Learn about the symptoms, causes and vaccine prevention of this contagious, disfiguring and sometimes fatal viral disease.

Snoring

Is the sound of snoring disrupting sleep in your household? Find out causes and treatment options for this common problem.

Social anxiety disorder (social phobia)

Learn more on this disorder where everyday interactions cause significant worry and self-consciousness because you fear being judged negatively by others.

Soft palate cancer

Learn about the symptoms of this type of cancer that forms in the back part of the mouth. Treatment options might include surgery, radiation and chemotherapy.

Soft tissue sarcoma

This rare type of cancer can begin in the muscles, fat, blood vessels, nerves, tendons and the lining of joints. Treatment usually includes surgery.

Solitary fibrous tumor

This rare type of tumor most often occurs near the lungs. Surgery is the preferred treatment. Radiation and chemotherapy may be needed in some instances.

Solitary rectal ulcer syndrome

Solitary rectal ulcer syndrome is a rare condition that's often linked to chronic constipation. Learn more about symptoms and treatment.

Somatic symptom disorder

Learn about symptoms, causes and treatment for this disorder, which is linked with major emotional distress and impairment.

Sore throat

Find out what causes this common affliction, when to see a doctor and what you can do to get relief from a sore throat.

Specific phobias

Specific phobias are an overwhelming and unreasonable fear of objects or situations that pose little real danger but provoke anxiety and avoidance.

Spermatocele

Learn more about this noncancerous testicular disorder that may require surgery if it's causing discomfort. But, the condition often needs no treatment.

Spider bites

Learn more about prevention, symptoms, complications and treatment of spider bites, which are usually harmless.

Spina bifida

Fetal surgery during pregnancy may improve outcomes for babies with myelomeningocele, a severe form of spina bifida. Learn the latest treatment options.

Spinal arteriovenous malformation (AVM)

Learn more about how this rare blood vessel disorder can affect the spinal cord.

Spinal cord injury

Learn more about what happens after your spinal cord has been damaged.

Spinal cord tumor

Spinal cord tumors can cause serious problems such as pain and paralysis. Find out how more about management and treatment.

Spinal headaches

These headaches can happen after a spinal tap procedure or spinal anesthesia, and usually don’t require treatment.

Spinal stenosis

Learn about this common back problem caused by narrowing of space in the spine. Lifestyle changes, physical therapy and medication can decrease the pain.

Spontaneous coronary artery dissection (SCAD)

A torn blood vessel in the heart can cause a heart attack. Learn about the diagnosis and treatment of this medical emergency.

Sprained ankle

Sprained ankle — Injury to a ligament of the ankle can usually be treated with at-home care and appropriate exercises to get you back on your feet.

Sprains

A sprain is a stretching or tearing of ligaments — the tough bands of tissue that connect two bones together in your joints. Ice and elevation can help.

Squamous cell carcinoma of the skin

Squamous cell carcinoma is a common skin cancer that usually looks like a red bump or a scaly sore. Learn about symptoms and explore treatment options.

Stage 4 prostate cancer

Find out how doctors diagnose and treat advanced prostate cancer that has spread to the lymph nodes or other parts of the body.

Staph infections

Learn about the symptoms, causes and treatment of these potentially lethal infections.

Stevens-Johnson syndrome

Learn more about the causes of this rare disorder of the skin and mucous membranes, its early signs, and whether it's preventable.

Stickler syndrome

This genetic disorder can cause serious vision, hearing and joint problems. Children may be born with a cleft palate and distinctive facial features.

Stomach cancer

Learn about cancer that forms in the stomach, including gastroesophageal junction cancer. Find out about symptoms, causes and treatments.

Stomach polyps

These masses of cells that form on your stomach lining usually don't cause signs or symptoms.

Strep throat

Learn more about the symptoms, causes and treatment of this throat bacterial infection in children and adults.

Stress fractures

Stress fractures are tiny cracks in bones often caused by overuse or osteoporosis. Learn how to prevent and treat them.

Stress incontinence

Coughing, laughing, running — all can lead to accidental urine leakage if you have stress incontinence. Learn about treatment options and self-care.

Stretch marks

Find out the symptoms of and treatment for this painless condition that causes streaks on the abdomen, breasts, hips, buttocks and thighs.

Stroke

Promptly spotting stroke symptoms leads to faster treatment and less damage to the brain.

Stuttering

Stuttering, sometimes called stammering, is a speech disorder that involves frequent and significant problems with normal fluency and flow of speech.

Sty

A sty is a painful red bump along the eyelash line that can often be treated with home remedies. Find out more about this irritating eyelid infection.

Subarachnoid hemorrhage

Find out more about diagnosis and treatment options for this bleeding in the brain.

Subconjunctival hemorrhage (broken blood vessel in eye)

Subconjunctival hemorrhage is a broken blood vessel in the eye — learn more about this common, harmless condition that clears up without treatment.

Sudden cardiac arrest

Learn about this medical emergency that involves sudden loss of heart function, and find out how fast, appropriate care might keep it from being deadly.

Sudden infant death syndrome (SIDS)

Learn about possible causes, risks and prevention of the sudden unexplained death of a seemingly healthy baby in the first year of life.

Suicide and suicidal thoughts

Suicide can be prevented. Learn suicide warning signs and how to reach out for immediate help and professional treatment.

Sun allergy

Learn more about the causes, symptoms and treatment of this itchy, red rash that is an allergic reaction to sunlight.

Sunburn

Long hours in the sun and unprotected skin mean one thing: sunburn. Here's what you can do for sunburn relief.

Supraventricular tachycardia

SVT is an irregularly fast heartbeat. For many people, treatment and lifestyle changes can control or eliminate this type of heart rhythm disorder (arrhythmia).

Suspicious breast lumps

Most breast lumps are benign, but it's important to see your doctor for a prompt evaluation.

Sweating and body odor

Learn more about the causes, treatment and self-care of this skin condition. Unusual changes may mean a medical problem.

Sweet's syndrome

Learn about the symptoms, causes and treatment of this painful skin condition that most often affects women between the ages of 30 and 60.

Swimmer's ear

The moist environment from water remaining in your ear after swimming or bathing can lead to this infection in the outer ear canal.

Swimmer's itch

Swimmer's itch — Learn more about the symptoms, treatment and prevention of this itchy rash that usually affects people swimming in freshwater lakes.

Swollen knee

Swollen knee — Comprehensive overview covers symptoms, causes, treatment of water on the knee.

Swollen lymph nodes

Learn more about swollen lymph nodes, including possible causes and treatments your doctor may recommend.

Synovial sarcoma

Synovial sarcoma is a rare type of cancer that tends to arise near large joints, particularly the knee, in young adults. The main treatment is surgery.

Syphilis

Understand how syphilis spreads, what you can do for prevention and how it’s treated.

Syringomyelia

The development of a fluid-filled cyst in the spinal cord can eventually damage the cord and cause symptoms such as pain and muscle weakness.

Systemic capillary leak syndrome

This rare disorder involves recurrent flares of plasma leakage. This causes a sharp drop in blood pressure, which can result in organ failure and death.

Systemic mastocytosis

Excess mast cells can build up in skin, bone and organs. When triggered, the cells release substances that can cause allergic reactions and organ damage.

TEN

Learn more about the causes, symptoms, treatment and risks of this life-threatening, rare skin disorder, also called toxic epidermal necrolysis.

TMJ disorders

Treatment options for pain in your jaw joint and in the muscles that control jaw movement can include pain management, medical therapies and surgery.

Tachycardia

Learn more about the symptoms and treatment of this heart rhythm disorder (arrhythmia), which causes a rapid heart rate.

Takayasu's arteritis

Understand this rare disease that damages the aorta, the large artery that carries blood from your heart to the rest of your body.

Tapeworm infection

This infection may have a major "ick" factor, but it usually only causes a mild intestinal illness.

Tay-Sachs disease

This rare, inherited disease causes a buildup of fatty acids that damages the brain and typically results in muscle control loss, blindness and paralysis.

Teen depression

This serious mental health problem affects how your teenager thinks, feels and behaves, and can cause emotional, functional and physical problems.

Temporal lobe seizure

These seizures begin in the temporal lobes of the brain, and can trigger a variety of symptoms, such as odd feelings, fear and unresponsiveness.

Tendinitis

Repetitive activities and weekend warrior exercise can aggravate tendons, causing pain and swelling.

Tennis elbow

Tennis elbow — Painful condition is caused by repetitive motions of the wrist and arm. Non-athletes are also affected. Learn how to prevent and treat it.

Tension headache

These common headaches are commonly triggered by stress and may be managed through a regimen of healthy habits and medications.

Testicular cancer

Mayo Clinic testicular cancer care reflects deep expertise across all the disciplines that your needs demand, working as an integrated team.

Testicular torsion

Sudden, severe pain in the scrotum could be testicular torsion. Learn about symptoms and treatment for this health emergency.

Tetanus

Learn about treatment of the serious bacterial infection commonly known as lockjaw and the vaccines that prevent it.

Tetralogy of Fallot

Learn more about a rare condition caused by a combination of four heart defects that are present at birth (congenital).

Thalassemia

Some forms of this inherited blood disorder usually show up before the age of 2, often causing anemia. More severe forms of the disease require regular blood transfusions.

Thoracic aortic aneurysm

Learn about this serious condition in which the upper part of the body's main artery becomes weak and may rupture.

Thoracic outlet syndrome

This group of disorders causes symptoms including pain or numbness due to pressure on the blood vessels or nerves between the collarbone and rib.

Throat cancer

Learn more about this type of cancer that affects your throat (pharynx), voice box (larynx) or tonsils.

Thrombocytopenia (low platelet count)

Thrombocytopenia — Comprehensive overview covers symptoms, causes, treatment of a low platelet count.

Thrombocytosis

This condition occurs when your body produces too many platelets, the cells that help blood clot. Thrombocytosis can cause clotting or bleeding problems.

Thrombophlebitis

Learn more about this inflammation of a blood vessel that can interrupt flow.

Thumb arthritis

This common condition can cause pain and mobility issues, making simple tasks difficult. Treatment may include medications, splints and sometimes surgery.

Thunderclap headaches

These headaches are sudden and severe, and can warn of a life-threatening condition — so seek immediate medical attention.

Thyroid cancer

Learn about thyroid cancer diagnosis and treatment, including thyroid surgery, radioactive iodine and thyroid hormone therapy.

Thyroid nodules

Find out what can cause lumps in the thyroid gland and how your doctor may treat them.

Tinea versicolor

Learn about the symptoms, causes, treatments of this common skin infection that usually responds to treatment.

Tinnitus

Tinnitus can be caused by many health conditions. As such, the symptoms and treatment options vary by person. Get the facts in this comprehensive overview.

Toe walking in children

Walking on toes or the balls of the feet is fairly common in children who are learning to walk. Most children outgrow it.

Tongue-tie (ankyloglossia)

With tongue-tie (ankyloglossia), a band of tissue (frenulum) tethers the tongue, restricting the range of motion. Learn about symptoms and treatment.

Tonsil cancer

Find out how doctors use innovative treatments such as transoral robotic surgery and proton therapy to treat this type of throat cancer.

Tonsillitis

Learn about the causes and treatment of tonsillitis, a common cause of sore throat in children.

Tooth abscess

A bacterial infection at the tip of the tooth root usually occurs from an untreated dental cavity, an injury or prior dental work.

Torn meniscus

Any activity that causes you to twist or rotate your knee, especially when putting your full weight on it, can cause this common knee injury.

Total anomalous pulmonary venous return (TAPVR)

In this congenital heart defect, the lung's blood vessels attach to the wrong places in the heart. Know the symptoms and how it's diagnosed.

Tourette syndrome

The repetitive movements and sounds called tics that characterize Tourette syndrome can affect daily life — but there are ways to manage them.

Toxic hepatitis

Find out about symptoms and treatment for toxic hepatitis — liver inflammation caused by exposure to certain substances, such as alcohol or medications.

Toxic shock syndrome

Toxic shock syndrome is a rare, potentially fatal complication of certain types of bacterial infections. Learn about symptoms, risk factors and treatment.

Toxoplasmosis

Read about symptoms, causes, treatment and tips for prevention of this parasitic infection that for some people, can cause severe complications.

Trachoma

Trachoma is the leading preventable cause of blindness worldwide. Find out about symptoms, treatment and prevention of this serious eye disease.

Transient global amnesia

When your memory suddenly disappears, it can be frightening — but transient global amnesia is typically temporary and harmless.

Transient ischemic attack (TIA)

This typically short bout of stroke-like symptoms doesn't cause permanent damage — but may serve as a warning sign of a future stroke.

Transposition of the great arteries

This serious, rare heart problem present at birth requires surgery to correct. Learn about its symptoms and treatment.

Transverse myelitis

This neurological disorder occurs when a section of the spinal cord is inflamed, causing pain, weakness, sensory problems and dysfunction in the body.

Traumatic brain injury

If a head injury causes a mild traumatic brain injury, long-term problems are rare. But a severe injury can mean significant problems.

Traveler's diarrhea

Learn how to avoid contaminated food and water that may lead to this common travel hazard. Plus, find out what to do if it strikes.

Trichinosis

Learn about the symptoms, treatment and prevention of this type of roundworm infection.

Trichomoniasis

This common sexually transmitted infection is caused by a parasite. Reduce your risk by using condoms when you have sex.

Trichotillomania (hair-pulling disorder)

Trichotillomania (hair-pulling disorder) involves recurrent, irresistible urges to pull out hair from your body. Therapy may help reduce or stop urges.

Tricuspid atresia

Learn how this congenital heart valve defect blocks blood flow from the heart to the lungs. Treatment involves multiple surgeries.

Tricuspid valve regurgitation

A leaky tricuspid valve may make you feel tired and have difficulty exercising. Learn how this type of heart valve disease is diagnosed and treated.

Trigeminal neuralgia

Learn about this painful nerve condition that can jolt areas on the face with electric-shock-like pain.

Trigger finger

Learn more about this painful condition that causes a finger to get stuck in a bent position, including how to treat it.

Triple X syndrome

Females with this genetic disorder have three X chromosomes instead of two. Symptoms can be mild or include developmental delays and learning disabilities.

Truncus arteriosus

Learn more about this rare heart defect that makes it difficult for the heart to pump the right amount of blood to the lungs and the body.

Tuberculosis

Learn about the symptoms, treatment and prevention of this common infectious disease.

Tuberous sclerosis

Tuberous sclerosis is a rare genetic disorder that causes noncancerous (benign) tumors ― unexpected overgrowths of normal tissue ― in parts of the body.

Tularemia

Tularemia is a rare infection caused by bacteria found mainly in wild animals. Learn how to prevent this infection and recognize its symptoms.

Turner syndrome

Turner syndrome affects only females as the result of a missing or partially missing X chromosome, causing a variety of medical and developmental problems.

Type 1 diabetes

Learn about the symptoms, causes, treatment of this chronic condition in which the pancreas produces little or no insulin.

Type 1 diabetes in children

Know what symptoms to look for, as well as more about diagnosis, treatment and daily living with this lifelong insulin-dependent condition.

Type 2 diabetes

High blood sugar levels are the key problem in diabetes. Learn about lifestyle changes to lower your risk and treatments to manage diabetes.

Type 2 diabetes in children

More children are being diagnosed with this blood sugar condition. Learn how to help manage or prevent this chronic disease in your child.

Typhoid fever

Learn more about the symptoms, cause and treatment of this serious intestinal illness.

Ulcerative colitis

Learn about symptoms and treatment of ulcerative colitis — an inflammatory bowel disease that causes swelling and sores in the digestive tract.

Umbilical hernia

Learn about this condition in which your intestines create a bulge near your navel.

Undescended testicle

Learn about causes, complications and treatment of this condition in which one or both testicles aren't in their normal place within the scrotum.

Undifferentiated pleomorphic sarcoma

Learn about this cancer that most often happens in the soft tissues of the arms and legs. Treatments include surgery, radiation therapy and chemotherapy.

Ureteral cancer

Find out how doctors use minimally invasive surgery to treat this rare cancer that forms in the tubes that connect your kidneys to your bladder.

Ureteral obstruction

Learn about what causes blockage of the tubes that carry urine from the kidneys to the bladder, tests you might need and how the condition can be treated.

Urethral stricture

Narrowing of the tube that carries urine from the body (urethra) can restrict urine flow and cause a variety of problems.

Urinary incontinence

Learn about possible causes of the loss of bladder control and what treatments are available for this problem.

Urinary tract infection (UTI)

Urinary symptoms — such as blood in the urine and burning with urination — could result from a UTI. Learn about UTI causes, treatments and self-care.

Urine color

Foods and medications can change the color of your urine. But a color change could be a sign of disease.

Uterine fibroids

Learn about these common noncancerous growths and what to do if you experience symptoms such as heavy menstrual bleeding.

Uterine polyps

Uterine polyps are tissue growths inside the uterus that can cause abnormal uterine bleeding or infertility. Learn about uterine polyp tests and treatment.

Uterine prolapse

Find out more about the symptoms and possible treatments, including surgical repair, for this pelvic floor disorder.

Uveitis

Uveitis is a form of eye inflammation that can cause pain, redness and blurry vision. Prompt treatment is important.

Vaginal agenesis

In this rare condition that occurs before birth, the vagina doesn't develop and the uterus may only develop partially or not at all. Learn about treatment.

Vaginal atrophy

Read about this condition that causes vaginal and urinary symptoms, often after menopause. It's also called genitourinary syndrome of menopause.

Vaginal cancer

Learn about vaginal cancer symptoms and diagnosis. Treatments for cancer of the vagina include surgery, radiation therapy and chemotherapy.

Vaginitis

Inflammation of the vagina can result in discharge, itching and pain. Recognize signs and symptoms and learn when to seek treatment.

Valley fever

Learn about symptoms and treatment for valley fever — an infection caused by fungi found in the soil of America's desert regions.

Varicocele

Find out how this condition involving the enlargement of veins in the scrotum can affect sperm quality and production.

Varicose veins

This common condition causes dark blue or purple lines or cords to develop under the skin. Learn self-care steps to take and what treatments are available.

Vascular dementia

Learn more about this stroke-related type of dementia that causes memory loss and reasoning problems. Prevention is possible, and good heart health is key.

Vascular rings

Learn more about this condition in which malformations of the aortic arch encircle the windpipe and esophagus and can press against them.

Vasculitis

An inflammation of the blood vessels, vasculitis may thicken and weaken blood vessel walls. If blood flow is restricted, organ damage can occur.

Vasovagal syncope

Learn about what causes a brief loss of consciousness and when to see a doctor if this happens to you.

Ventricular fibrillation

Without fast treatment, this heart rhythm problem can cause death within minutes. Learn the warning signs and what actions to take to save a life.

Ventricular septal defect (VSD)

Learn more about diagnosis and treatment of this common heart defect present at birth in which a hole occurs in the wall between the lower heart chambers.

Ventricular tachycardia

This rapid heart rate can be a medical emergency. Know the warning signs and how it's treated.

Vertebral tumor

Vertebral tumors grow in the bones of the spine, causing pain and weakening the spinal column. Read more about how they’re managed, and what to expect.

Vesicoureteral reflux

Learn about what happens if urine flows backward from the bladder. Usually found in children, this condition boosts the risk of urinary tract infections.

Viral gastroenteritis (stomach flu)

This condition, often called stomach flu, is usually harmless, except for infants and people with immunosuppression. Symptoms can usually be managed.

Viral hemorrhagic fevers

Learn more about the symptoms, treatment and prevention of these sometimes deadly diseases.

Vitamin deficiency anemia

A lack of folate and vitamin B-12 can cause a type of anemia in which red blood cells become too large and can't carry oxygen properly.

Vitiligo

Learn more about this condition in which your skin loses pigment cells, resulting in very light or white patches on parts of the body.

Vocal cord paralysis

Find out more about this condition caused by problems with the nerves that control your voice box.

Voice disorders

Learn more about the causes of common voice disorders, such as laryngitis and granuloma, and how Mayo Clinic diagnoses and treats them.

Von Willebrand disease

Learn more about the symptoms, causes, diagnosis, treatment of this inherited bleeding disorder in which blood doesn't clot well.

Vulvar cancer

Learn about this rare cancer that forms on the skin that surrounds the urethra and vagina. Treatments include surgery, radiation and chemotherapy.

Vulvodynia

If you have pain, burning or irritation in your vaginal area, talk to your doctor. You could have vulvodynia.

Waldenstrom macroglobulinemia

Learn about this rare type of white blood cell cancer. Treatments include chemotherapy, targeted therapy, immunotherapy and bone marrow transplant.

West Nile virus

Learn more about the symptoms, treatment and prevention of this mosquito-borne illness.

Wet macular degeneration

Blurred vision or blind spots could be signs of wet macular degeneration. Find out about symptoms and treatment for this chronic eye disorder.

Wheat allergy

Learn about the causes, symptoms and treatment of wheat allergy and how they differ from those of celiac disease. Managing either condition means avoiding wheat.

Whiplash

Whiplash is a common neck injury, often resulting from a car crash. But other trauma can cause it, too. Know the symptoms and how to treat it.

Whipple's disease

Learn more about the symptoms, causes and treatment of this rare primarily digestive infection.

Whooping cough

Learn more about the symptoms, causes, treatment of this highly contagious, vaccine-preventable lung infection.

Wilms' tumor

Advancements in the diagnosis and treatment of Wilms' tumor have greatly improved the outlook (prognosis) for children with this type of kidney cancer.

Wilson's disease

Wilson's disease, an inherited disorder, causes copper to accumulate in vital organs. It's treatable when diagnosed early.

Wolff-Parkinson-White (WPW) syndrome

In WPW syndrome, an extra pathway between the heart's upper and lower chambers causes a fast heartbeat. Rarely, it can cause sudden cardiac death.

Wrinkles

This natural part of aging that causes creases in the skin is also affected by sun exposure and smoking. Learn about the treatment options at Mayo Clinic.

Wrist pain

Wrist pain can be caused by many factors, ranging from sudden injuries to long-term problems such as arthritis. Treatment varies by cause.

X-linked agammaglobulinemia

This genetic disease weakens the immune system — mainly in males — and leads to frequent infections.

Yeast infection (vaginal)

Vaginal itching or burning could mean you have a yeast infection. Learn about other symptoms and effective treatments for this uncomfortable condition.

Yellow fever

Understand the symptoms and how to protect yourself with a vaccine for this sometimes deadly mosquito-borne disease.

Yips

Learn about what causes these involuntary wrist spasms that often frustrate golfers.

Zika virus

This mosquito-borne illness causes no symptoms or only mild symptoms in most people, but it is a serious concern for pregnant women. Know what to look for.

Zollinger-Ellison syndrome

In this rare disease, tumors in the digestive tract cause excess production of a hormone that increases stomach acid, leading to peptic ulcers.