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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

With this condition, which can occur after a major illness or injury, fluid builds up in the lungs' air sacs so that less oxygen reaches the blood.

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 the treatment.

Absence seizure

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

Acanthosis nigricans

Learn about the causes of and treatment for this condition that causes dark, velvety patches in folds of the skin.

Achalasia

In this condition, the muscles in the esophagus don't relax, preventing food and drink from moving into the stomach. 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

This noncancerous tumor can sometimes grow on the nerve in the head that affects hearing and balance.

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

Know the symptoms, causes and treatment of this heart condition. The term refers to many conditions that cause sudden, low blood flow to the heart.

Acute flaccid myelitis (AFM)

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

Acute kidney injury

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

Acute liver failure

A rapid loss of liver function can occur in people who don't even have liver disease. Find out about symptoms, treatment and prevention of this serious medical emergency.

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 ways to treat and prevent the stuffy nose and head pain that can come with this 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

These are unhealthy reactions to stress that involve emotions and behavior. The response to stress is much more intense than would usually be expected.

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 disease

Learn about symptoms, complications and 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 public 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, the body makes little or no 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

This condition is due to drinking large amounts of alcohol in a short time. It is serious and can be deadly. 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

Heavy drinking over years can damage the liver.

Allergies

Allergy symptoms can range from mild to severe, even life-threatening. Find out what treatments and prevention tips 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

Understand more about this brain disorder that's the most common cause of dementia. Also learn about new tests and medicines on the market.

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 what can cause memory loss and learn steps you can take to manage it.

Ampullary cancer

Learn more about the causes, diagnosis and treatments for cancer of the ampulla of Vater.

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

Having too few healthy red blood cells causes tiredness and weakness. There are many types of this condition.

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 chest pain is a symptom of 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

People with this eating disorder have a very low body weight, an intense fear of gaining weight and a flawed way of seeing their body.

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

This includes ignoring right and wrong, lying, treating others harshly, and not caring about hurting others. Charm or wit is used to manipulate others.

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.

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 that 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 communication disorder 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 symptoms and treatment for inflammation of the appendix.

Arteriosclerosis / atherosclerosis

Learn about the symptoms, causes and treatments 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

In this condition, a tangle of blood vessels 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 use quick-relief treatment or get emergency care.

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, this loss of muscle control and coordination can impact movement, speech and swallowing.

Atelectasis

Atelectasis means a collapse of the whole lung or an area of the lung. It's one of the most common breathing complications after surgery.

Athlete's foot

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

Atopic dermatitis (eczema)

Learn about the causes, symptoms and treatments of this itchy rash that most often begins before age 5, is persistent, and has periods of clearing and relapse.

Atrial fibrillation

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

Atrial septal defect (ASD)

This heart problem that is present at birth causes a hole between the heart's upper chambers. It 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 involves a hole in the heart. It affects blood flow through the heart valves. Learn the symptoms and 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 genitalia

In this rare condition, a baby's genitals are not clearly male or female. Genitals may not be fully developed or the baby may have features of more than one sex.

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.

Auditory processing disorder (APD)

This type of hearing loss involves the brain. Learn about ways that can help people with the condition hear better.

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 happens when the immune system attacks the liver with destructive antibodies. Immune-suppressing medicine 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 seek medical help. Home treatment and proper body mechanics often can treat back pain within a few weeks.

Bacterial vaginosis

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

Bad breath

This condition, also called halitosis, most often is caused by certain foods, health conditions and habits. Learn how to treat and prevent it.

Bags under eyes

Learn about causes, treatments and self care for bags under eyes, which become more common as you age.

Baker cyst

This fluid-filled cyst occurs behind the knee and can be caused by arthritis or a cartilage tear. Treating the cause usually provides relief.

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

Learn about causes and treatments of bed-wetting, including moisture alarms, bladder training and medicines.

Bedbugs

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

Bedsores (pressure ulcers)

These areas of damaged skin and tissue are caused by sustained pressure — often from a bed or wheelchair — that reduces blood flow to vulnerable areas of the body.

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 this condition that causes temporary facial paralysis. Find out why it happens and what to do about it.

Benign adrenal tumors

Most of these tumors need no treatment, but some do. Learn about diagnosis and treatment options.

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 the brain and spinal cord.

Benign prostatic hyperplasia (BPH)

This common problem, also known as an enlarged prostate, can be treated.

Bicuspid aortic valve

This condition, present at birth, affects the valve between the lower left heart chamber and the body's main artery. Know the symptoms and treatment.

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 this condition often don't feel able to stop eating and may eat larger than usual amounts of food. Learn about symptoms and treatment.

Bipolar disorder

This mental health condition causes extreme mood swings that include emotional highs, called mania, and lows, known as depression.

Bird flu (avian influenza)

Flu viruses in other animals, such as birds, may be a risk to people. Learn more about the symptoms, causes, prevention and treatment for bird flu in people.

Black hairy tongue

This condition gives the tongue a dark, furry look. It results from a buildup of dead skin cells on the many tiny, rounded bumps on the tongue's surface.

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)

Lots of things can cause bloody urine. Some are serious problems, and others are harmless. Find out why it's always important to get a checkup.

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 types happen mostly 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 these bony growths.

Borderline personality disorder

This mental health condition affects how you see yourself. It includes unstable and intense relationships, extreme emotions, and impulsiveness.

Botulism

This rare but serious condition can be caused by bacteria that have contaminated food or a wound. Learn more about how to prevent botulism.

Brachial plexus injury

Learn about these nerve injuries that usually result from auto or motorcycle accidents, and find out 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)

Tangled blood vessels in the brain affect typical blood flow in this rare condition. Learn more.

Brain aneurysm

Learn about the 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 types, signs, symptoms and causes of brain tumors, which are growths of cells in the brain.

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

This common injury is usually the result of falling, playing sports or being in a traffic accident.

Broken foot

This injury is painful but rarely needs surgery for repair. Healing can take weeks to months.

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

Treatment of a broken leg depends on the location and severity of the injury. Surgical repair uses metal pins and plates to hold the fragments together.

Broken nose

A broken nose can cause pain, swelling and bruising around your nose and eyes. Surgery usually isn't necessary.

Broken ribs

This common injury happens most often because of falls, car accidents or contact sports.

Broken toe

Pain when wearing shoes and difficulty walking can signal a broken toe — so see your health care provider 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 of the lungs is common in young kids and babies. Symptoms may include coughing, wheezing and trouble breathing.

Bronchitis

The lining of the tubes that carry air to and from your lungs is inflamed. Signs and symptoms include cough, mucus, fatigue and chest discomfort.

Brucellosis

Brucellosis is an infectious bacterial disease often spread via direct contact with infected animals or contaminated animal products.

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 disease

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

Bulimia nervosa

In this serious eating disorder, people lose control and eat large amounts of food. Then they get rid of it in unhealthy ways by purging, such as vomiting.

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 blockage in the heart's signaling pathways can interrupt the heartbeat and make it harder for the 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 burning sensation, without an obvious cause, may affect the tongue, gums, lips, cheeks, roof of your mouth or large areas of your mouth.

Burns

Learn about causes, symptoms, risk factors and complications of burns and how to prevent and treat them.

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, people who get it are in health care facilities.

COPD

This ongoing lung disease limits airflow into and out of the lungs. This results in trouble breathing, cough with mucus and wheezing.

CSF leak (Cerebrospinal fluid leak)

Cerebrospinal fluid leaks may start in 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

This gas has no color, odor or taste. It can be deadly. Learn how to 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 this condition that can lead to a stroke, how it's treated and ways to prevent it.

Carpal tunnel syndrome

Learn more about the symptoms and treatment of this common nerve condition affecting the hand and arm.

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

Cavities and tooth decay

These areas in the hard surface of your teeth are tiny openings or holes due to damage from tooth decay. This can lead to pain, infection and tooth loss.

Celiac disease

In this digestive condition, 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 nervous system vascular malformations

Several types of this condition affect the blood vessels in the brain or spinal cord.

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

Learn about this group of conditions that affect movement. It's caused by damage to the developing brain, usually before birth.

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

Pain in the chest 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

Learn about this brain condition in which brain tissue extends into the spinal canal.

Chickenpox

Learn more about preventing this once-common childhood illness. Also, find out how to recognize and manage it.

Chilblains

Learn how to prevent and treat this seasonal skin condition that causes injury to unprotected skin of young women when it's cold but not freezing.

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

This speech disorder is caused by a problem with communication between the brain and the muscles used for speech. Speech therapy can help.

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

This common sexually transmitted infection (STI) can lead to serious health problems if left untreated. Learn more about symptoms, treatment and 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

Learn the causes, symptoms, complications and treatment of gallbladder inflammation.

Cholera

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

Cholestasis of pregnancy

This liver condition can occur late in pregnancy, triggering intense itching. The risk of complications for your baby may require early delivery.

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 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 painful, itchy, recurring welts is diagnosed and what treatments may offer relief.

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 symptoms and causes. Find out how CML is treated, including targeted therapy and bone marrow transplant.

Chronic pelvic pain

Ongoing pain in the pelvis can be a symptom of another disease or a condition in its own right. Learn how it's diagnosed and treated.

Chronic sinusitis

Read about possible causes of lasting sinus troubles, treatments and how to prevent these problems.

Chronic traumatic encephalopathy

This type of brain degeneration is likely caused by recurrent concussions, but the disorder 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

This advanced stage of liver damage often shows no symptoms until it's quite serious. 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 bouts called cluster periods.

Coarctation of the aorta

This heart condition is usually present at birth. It's treatable but requires lifelong health checkups. Learn about the causes and treatment.

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 causes for this cancer that starts in the large intestine. 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

Learn what can cause this state of prolonged loss of consciousness. While a coma rarely lasts longer than a few weeks, some people never wake from one.

Common cold

This common illness of the nose and throat causes a stuffy or runny nose, sore throat, and cough.

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

Also called gambling disorder, compulsive gambling is the uncontrollable urge to keep gambling despite the toll it takes on your life.

Compulsive sexual behavior

Also called sexual addiction, this means being obsessed with sexual fantasies, urges, or behaviors that disrupt your life or cause harm to you or others.

Concussion

This brain injury can cause headaches, dizziness, trouble concentrating and other symptoms that often improve within days to weeks.

Congenital adrenal hyperplasia

This group of inherited genetic conditions limits the adrenal glands' ability to make certain vital hormones.

Congenital diaphragmatic hernia (CDH)

In CDH, a baby's diaphragm — the muscle that separates the chest from the abdomen — develops a hole called a hernia. Learn about treatment before birth.

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 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

These heart problems at birth cause the mitral valve to leak or become narrowed. Know the symptoms and treatment.

Congenital myasthenic syndromes

These rare hereditary conditions result in a problem in nerve stimulation, causing muscle weakness that worsens with physical activity.

Conjoined twins

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

Constipation

Learn how to prevent and treat infrequent or painful passing of stool.

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 an itchy rash. Here's how to manage this common form of dermatitis.

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

Know the warning signs of this common heart condition often caused by clogged, narrowed arteries and how lifestyle changes can lower your risk.

Coronavirus disease 2019 (COVID-19)

Coronavirus disease 2019 (COVID-19) is an illness caused by the virus SARS-CoV-2. Learn more about the symptoms, risks and ways to protect yourself.

Corticobasal degeneration (corticobasal syndrome)

Learn about this rare disease that affects brain cells. The disease can make it hard to speak, move and think.

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 what can put someone at risk of developing this rare brain disorder that causes dementia.

Crohn's disease

Learn about symptoms and treatment for this debilitating, but treatable, digestive condition.

Croup

This upper airway infection makes it harder to breathe and causes a barking cough. It involves swelling around the voice box, windpipe and bronchial tubes.

Cryoglobulinemia

When atypical proteins in the blood clump together at temperatures below 98.6 F (37 C), the clump can block blood flow and damage the 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.

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 a condition that affects the bladder. It happens most often when bacteria cause an infection. But there are other causes, too.

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 tenosynovitis

This painful condition affects the tendons on the thumb side of the wrist. A splint or brace can rest the tendons. Ice also is helpful.

Deep vein thrombosis (DVT)

This potentially serious condition can occur with few or no symptoms. 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 can cause 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

Learn what may cause this change in mental abilities. Symptoms develop fast and include confusion and being unaware of surroundings.

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

This mental health condition causes you to feel like you're seeing yourself from outside your body or that things around you are not real, or both.

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 symptoms, causes and treatments of this itchy skin condition that affects children and adults, and about how moisturizers help prevent it.

Dermatofibrosarcoma protuberans

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

Dermatographia (Dermatographism)

Learn about the symptoms, causes and treatment of this skin condition in which light scratching causes raised lines or welts.

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.

Desmoplastic small round cell tumors

These rare, aggressive cancers most often form in the abdomen. Learn about DSRCT treatments, including surgery, chemotherapy and radiation therapy.

Deviated septum

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

DiGeorge syndrome (22q11.2 deletion syndrome)

This condition is due to missing part of chromosome 22. It may cause heart issues, thyroid problems, cleft palate, lower immunity and other health problems.

Diabetes

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

Diabetes insipidus

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

Diabetic coma

iabetic coma is a life-threatening disorder that can happen when blood sugar is very high or very low. Learn about its causes, treatment and prevention.

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)

Managing diabetes can prevent or delay this common diabetes complication that affects the 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

Learn more about the causes, prevention and home remedies for this common condition that irritates skin under diapers.

Diarrhea

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

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 shoulder

This shoulder injury, which occurs in the body's most mobile joint, causes the upper arm bone to pop out of its socket.

Dissociative disorders

These mental health conditions involve experiencing a loss of connection between thoughts, memories, surroundings, actions and identity.

Diverticulitis

This common colon disease develops when small pouches form in the colon wall and become inflamed, causing pain, fever and abnormal stool 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 condition of the uterus. It is present at birth.

Double-outlet right ventricle

In this heart condition present at birth, two major blood vessels aren't attached to the heart in the usual positions. Learn how it's treated.

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 this condition that involves swelling and irritation of the sac around the heart after damage to the heart muscle.

Drug addiction (substance use disorder)

Drug addiction affects your brain and behavior to the point where you can't control your use of legal or illegal drugs, even when you know they cause harm.

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

Eyes feeling dry and uncomfortable? Inadequate tear production is a common — and very treatable — eye condition. Find out what causes it 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

With this condition, also known as xerostomia, the salivary glands in the mouth don't make enough saliva to keep the 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

This painful condition can happen after tooth removal. A blood clot where the tooth was removed does not form, comes out or dissolves before wound healing.

Ductal carcinoma in situ (DCIS)

Noninvasive breast cancer often has no symptoms. Find out about the causes, diagnosis and treatment of this form of breast cancer.

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 contracture

This condition causes one or more fingers to bend toward the palm of the hand. The affected fingers can't straighten completely.

Dural arteriovenous fistulas

Learn about these rare, irregular connections that can occur between arteries and veins in the protective covering of the brain and spinal cord.

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 painful, itchy little blisters on the hands and soles of the feet.

Dyslexia

This learning disorder involves difficulty reading due to problems identifying speech sounds and learning how they relate to letters and words.

Dysphagia

Having trouble swallowing? Learn more about what causes this common issue, along with therapies for treating the condition.

Dystonia

Find out more about this painful movement 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

Anorexia, bulimia and binge-eating disorder affect physical and mental health. Learn about symptoms, causes, risk factors, diagnosis and treatment options.

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 swelling caused by too much fluid in body tissues.

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

This complication of an unrepaired congenital heart defect needs to be watched closely. Learn how treatment can help manage symptoms.

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

Learn about these malignant brain tumors that happen most often in babies and young children. Treatments include surgery, radiation therapy and chemotherapy.

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 fatal condition associated with inflammation of the brain and what you can do to prevent it.

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, and chemotherapy and other medicines.

Endometriosis

Learn about endometriosis, including possible treatments for this condition that can cause pain and sometimes infertility.

Enlarged breasts in men (gynecomastia)

Learn how an imbalance of the hormones estrogen and testosterone can cause breast tissue swelling 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, radiation therapy and chemotherapy.

Epidermoid cysts

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

Epidermolysis bullosa

Learn about a rare inherited disease that often shows up in infancy and causes fragile, blistering skin on the palms and feet. Severe disease may be fatal.

Epididymitis

This inflammation of the coiled tube at the back of the testicle that stores and carries sperm is usually caused by a bacterial infection.

Epiglottitis

A blocked windpipe needs prompt treatment.

Epilepsy

Learn about this condition that causes seizures. Find out which symptoms are associated with different types of seizures and how they're treated.

Epithelioid sarcoma

This rare, slow-growing soft tissue cancer tends to occur in teenagers and young adults. It often starts in a hand, wrist, arm or leg.

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

Learn about the symptoms, diagnosis and treatments for this type of cancer that begins in the tube that connects the throat and the stomach.

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 liver disease complication.

Esophagitis

An inflamed, sore esophagus can make it difficult to swallow and cause chest pain when you eat. Find out what causes this painful condition and your options for treatment.

Essential tremor

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

Esthesioneuroblastoma

This cancer begins in the upper part of the inside of the nose. Treatment usually involves surgery. Other options include radiation therapy and chemotherapy.

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. Medicine 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 issue 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

This condition results from alcohol exposure before birth. The exposure causes lifelong problems with behavior, learning, thinking and physical development.

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

Learn about this common breast lump. It is not cancer. 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 belly area.

Fibromyalgia

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

Flatfeet

A common and usually painless condition, flatfeet occurs when the arches of the feet flatten upon standing, allowing the entire soles to touch the floor.

Floor of the mouth cancer

Learn about the symptoms of this type of cancer that forms under the 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 foodborne illnesses that can cause upset stomach, 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 from a mental illness.

Frontotemporal dementia

Read more about this less common type of dementia that can lead to personality changes and trouble with speech and movement.

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

This painful condition usually begins gradually and makes the shoulder hard to move. Exercises can help restore range of motion.

Fuchs dystrophy

Fuchs dystrophy may cause eye pain and vision problems that get worse over time. Medicines can help but surgery may be needed.

Functional dyspepsia

Learn about functional dyspepsia, a digestive disorder with no clear cause. Treatment may help relieve this common condition.

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

This type of milky nipple discharge happens to people who aren't breastfeeding. Find out more about the possible causes and treatments.

Gallbladder cancer

Learn about this cancer that begins in the gallbladder. Treatment most often 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

These fluid-filled, noncancerous lumps most often appear on wrists, hands or feet.

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

Learn about the causes and treatments for this inflammation of the stomach lining.

Gastroesophageal reflux disease (GERD)

If stomach acid washes back into the esophagus, it can cause 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

This digestive condition affects muscles in the stomach and keeps it from emptying fully. Learn about symptoms and treatment.

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

This sexually transmitted infection can't be cured. Learn how it can be managed and how to prevent the spread of infection.

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 does not cause health issues. Sometimes it can cause tongue pain and make you more sensitive 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 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

Regular eye exams may catch glaucoma early and save your eyesight. Find out about symptoms and treatment for this vision-stealing eye disease.

Glioblastoma

This fast-growing cancer starts in the brain or spinal cord. Treatments include surgery, radiation and chemotherapy.

Glioma

Gliomas are the most common brain tumors in adults. 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 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.

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 condition that results in too much thyroid hormone.

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 condition affects the nerves, causing weakness and tingling in the arms and legs that quickly spreads throughout the body.

H1N1 flu (swine flu)

Find out more about 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. When hairy cell leukemia treatment is needed, it usually starts with chemotherapy.

Hammertoe and mallet toe

Low-heeled shoes that leave enough room for the toes can help prevent this bend in a toe or ease the pain of it.

Hamstring injury

Self-care measures, such as rest and ice, might be all that's needed for an injury to one of the hamstring muscles.

Hand-foot-and-mouth disease

Learn about the symptoms and treatment of this contagious viral infection. It is marked by sores in the mouth and a rash on the hands and feet.

Hangovers

Unpleasant symptoms can happen after drinking too much alcohol. But serious symptoms may mean 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 and neck cancers

Learn about innovative treatment for throat cancers, mouth cancers, tongue cancers, tonsil cancers and other cancers that affect the head and neck.

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 cardiovascular 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. Find out what treatments help you live longer and may even strengthen your heart.

Heart murmurs

An irregular heart sound may be harmless or worrisome. Know the causes of heart murmurs and when treatment is needed.

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 the 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.

Heavy menstrual bleeding

Learn about the causes and treatment of heavy menstrual periods.

Helicobacter pylori (H. pylori) infection

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

Hemangioma

This red mark on a baby's skin looks like a rubbery bump or flat red mark and is made up of extra blood vessels in the skin. It generally goes away by age 10. Learn more about its causes and treatment.

Hemifacial spasm

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

Hemochromatosis

This liver disorder causes your body to absorb too much iron from the foods you eat. Learn about symptoms, causes and treatment for this condition that usually runs in families.

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 the 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

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

Hepatitis B

This serious liver infection is caused by a virus that spreads easily. Learn about the symptoms, treatment and how to prevent it.

Hepatitis C

Many people with this infection don't know they have it. Find out about symptoms and treatment for this liver disease that can be dangerous.

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 spasms of your diaphragm that you can't control, hiccups are usually harmless. Rarely, hiccups may be a sign of an underlying medical problem.

Hidradenitis suppurativa

This condition causes small, painful lumps to form where your skin rubs together. The lumps heal and return and can lead to the formation of tunnels and scarring.

High blood pressure (hypertension)

Learn the symptoms and treatment of this condition — which raises the 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

This mental health condition involves ongoing difficulty parting with possessions, leading to severe clutter and a risk to safety.

Hodgkin lymphoma (Hodgkin 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.

Huntington's disease

This rare disease causes an early decay of nerve cells in the brain. Learn about its symptoms 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 treatments for this swelling in the scrotum.

Hydrocephalus

Learn about this potentially fatal condition that causes fluid buildup in the brain. It can cause 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

This condition can weaken bones, create kidney stones, and affect how well the 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 these rare kidney problems.

Hyperparathyroidism

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

Hyperthyroidism (overactive thyroid)

Understand what happens when your thyroid is overactive and learn about treatment 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 condition caused by a problem with the pituitary gland.

Hypoplastic left heart syndrome

Learn more about this rare congenital heart defect that causes the left side of the heart to not develop fully and be small.

Hypospadias

This condition happens before birth. The opening of the urethra is on the underside of the penis instead of at the tip. Learn about treatment.

Hypothermia

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

Hypothyroidism (underactive thyroid)

Understand what happens when your thyroid is underactive and learn about treatment for this condition.

Idiopathic hypersomnia

This 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 disease)

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

These teeth don't have enough room to come in or develop properly, leading to pain, damage to other teeth and other dental problems.

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, putting a pregnancy at risk. Learn more about this hard-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

Learn more about when a baby spits up food or liquid. Most babies outgrow this common and messy condition by the age of 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 not being able to get pregnant. Learn the 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 swollen breast. Treatments include surgery, radiation, chemotherapy and others.

Influenza (flu)

Learn more about the symptoms, causes and prevention of this potentially deadly 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.

Inherited metabolic disorders

Caused by gene changes, these disorders affect the body's ability to change food into energy. They also affect how energy is used, such as for cell repair.

Insomnia

This disorder can make it hard to fall asleep, hard to stay asleep or both, even though you have the chance for enough sleep. It can drain your energy.

Intermittent explosive disorder

This mental health condition involves sudden bouts 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 about what happens when blood flow to part of the small or large intestine is blocked, 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 a head injury.

Intracranial venous malformations

Find out more about the diagnosis and treatment of these unusually enlarged veins in the brain.

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

Lifestyle changes can make a big difference when it comes to managing this common GI disorder. Learn more about symptoms, diagnosis, and how to avoid triggers for this long-term condition.

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 but are rarely life-threatening.

Jet lag disorder

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

Jock itch

Learn more about this common, treatable fungal infection that causes an 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 sarcoma

This cancer caused by a virus occurs in people who have AIDS and those with a donated organ who take medicines to prevent organ rejection.

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 can be a minor nuisance — but sometimes it means a more serious problem. Find out about symptoms, treatment and prevention for this potentially dangerous eye condition.

Keratoconus

When your cornea bulges outward, it can cause blurry vision and make your eyes sensitive to light. Find out about symptoms, causes and treatment for this eye condition.

Keratosis pilaris

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

Kidney cancer

Learn about the symptoms, diagnosis and treatments for this type of cancer that begins in the kidney.

Kidney cysts

These round, fluid-filled pouches on or in the kidneys are sometimes discovered during imaging tests. Find out when treatment may be needed.

Kidney infection

A urinary tract infection that travels to the kidneys can be dangerous. Know the symptoms and when to get prompt medical treatment.

Kidney stones

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

Kleptomania

If you have this impulse control disorder, you can't 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

This condition involves painful swelling of a small fluid-filled sac near the knee joint. It causes pain and can limit movement.

Knee pain

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

Kyphosis

This excessive 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

This allergy is a reaction to proteins in natural rubber latex — found in medical gloves, balloons and more. Find out how to avoid many common triggers.

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 the heart's main pumping chamber to become enlarged and thickened.

Legg-Calve-Perthes disease

This childhood condition occurs when blood supply to the ball part of the hip joint is interrupted for a short time, making the bone 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

This mouth condition appears as thick, white patches on the gums, the cheeks and the bottom of the mouth that cannot be scraped off.

Lewy body dementia

This common dementia is caused by a buildup of proteins in the brain. It affects thinking, memory and movement.

Lice

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

Lichen planus

Learn about the causes, symptoms and treatment of this 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 vital tasks 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 disorder that can cause fast, chaotic heartbeats.

Low blood pressure (hypotension)

This condition isn't always a concern. But sometimes it can cause dizziness and fainting or be life-threatening. Learn when it needs treatment.

Low sex drive in women

Many women have dips in sexual desire at some point. But you can get your sex drive back. Learn about the causes and treatments 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 symptoms, diagnosis and treatment for this deadly form of cancer.

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 effect of lupus on the kidneys, including symptoms to watch for, how it's diagnosed and what treatments are available.

Lyme disease

Learn about the symptoms, diagnosis and treatment of this common tick-borne illness.

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 lymphoma and non-Hodgkin lymphoma.

Lynch syndrome

Learn about this condition caused by inherited genes that increase the risk of colon cancer, endometrial cancer and other kinds of cancer.

MCAD deficiency

This inherited genetic disorder prevents the breakdown of certain fats needed for energy, leading to dangerously low blood sugar levels 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. 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

These cancers 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

Pain and swelling in the breast could be caused by this breast condition. Find out about 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 symptoms.

Medication overuse headaches

When medicines that ease headache pain are used too often, they can 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 the symptoms, diagnosis and treatments for the most serious form of skin cancer.

Meniere's disease

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

Meningioma

This is the most common type of tumor that forms in the head and may affect the brain. Find out about 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 major life change and learn how to manage hot flashes and other menopause symptoms.

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.

Meralgia paresthetica

Learn about this condition that causes burning, tingling and numbness in the thigh, and how to get relief.

Merkel cell carcinoma

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

Mesenteric ischemia

This condition can come on suddenly or develop over time. Find out more about symptoms and treatment for this condition that restricts blood flow to the small intestine.

Mesenteric lymphadenitis

This condition involves swollen lymph nodes in the membrane that connects the bowel to the abdominal wall. It 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

Learn more about microcephaly, when an infant's head is smaller than expected. The condition affects child development.

Microscopic colitis

Ongoing, watery diarrhea could be a sign of this condition of the colon. Find out about testing and treatment.

Migraine

Find out about painful migraines that can last hours to days. Also can cause nausea and vomiting and reacting 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 typical cognitive decline of aging and the more serious decline of dementia.

Milk allergy

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

Miscarriage

Learn what might cause the loss of a pregnancy, the symptoms and how to cope.

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 this most common heart valve condition, which causes blood to leak backward in the heart.

Mitral valve stenosis

When the valve between the left heart chambers is narrowed, the heart doesn't get enough blood. Know the symptoms, causes and treatment of this type of heart valve disease.

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

This rare pregnancy complication 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

Moles, also known as nevi, are a common type of skin growth that vary in color, shape and size. While most moles are most often harmless, they rarely can become cancerous.

Molluscum contagiosum

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

Monoclonal gammopathy of undetermined significance (MGUS)

When bone marrow produces an unusual protein in the blood, it can sometimes lead to certain types of blood cancer.

Mononucleosis

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

Mood disorders

These conditions affect emotions. Depression causes a feeling of deep sadness. Bipolar disorder goes back and forth from being very sad to being very happy.

Morning sickness

Learn more about nausea and vomiting during pregnancy. Learn about 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

Learn about the many ways to prevent mosquito bites and how to ease the itch if you are bitten.

Mouth cancer

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

Movement disorders

Learn about the different types of neurological conditions that affect movement.

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 this rare condition that causes tumors to grow and too many hormones to be made.

Multiple endocrine neoplasia, type 2 (MEN 2)

Learn about this rare disorder that causes tumors and overproduction of hormones.

Multiple myeloma

Learn about this cancer that forms from white blood cells called plasma cells. Treatments include medicines 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

This rare condition affects movement, blood pressure and other functions of the body.

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

Learn about 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 vaccines can prevent it.

Muscle cramp

Learn about this sudden, painful tightening of a muscle and what to do about it.

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.

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)

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

Myasthenia gravis

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

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD)

Learn about the symptoms, diagnosis and treatments for this autoimmune disease that attacks nerve fibers in the body.

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 certain points in the muscles, called trigger points, can cause ongoing muscle pain.

Myxofibrosarcoma

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

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 disorder includes an unreasonably high sense of importance, a 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

These painless, noncancerous growths can lead to a lost sense of smell or infection. Medicine 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 effective treatment options for this eye condition, and some preventive options are emerging.

Neck pain

This common ailment can be the result of poor posture or osteoarthritis. Rarely, it can indicate a more serious issue.

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 about this itchy skin condition that can disrupt your sleep and daily activities. Treatment focuses on controlling itching and preventing scratching.

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

Learn about this type of peripheral nerve tumor that forms a soft bump on or under the skin. It can appear anywhere in the body.

Neurofibromatosis type 1

This genetic condition causes tumors on nerve tissue. Surgery and other therapies can manage 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 disease

A condition passed down in families that affects how the body breaks down and uses fats. Fat buildup in cells damages 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

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

Nonallergic rhinitis

Many things can trigger this problem. 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

This genetic condition stops typical development in parts of the body. It may include unusual facial features, short height, heart problems or other issues.

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 unwanted thoughts and fears, or obsessions. These obsessions lead to repetitive behaviors, also known as compulsions, that get in the way of 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 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)

This childhood mental health condition 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)

This form of low blood pressure might cause dizziness, lightheadedness or fainting when rising 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 happens 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 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)

Pain during sex can happen for many reasons, ranging from physical conditions to emotional concerns. Medicines or other therapies may help.

Pancreatic cancer

Learn about symptoms, risk factors, prevention, diagnosis, surgery, chemotherapy and other treatments 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 digestive system disorder that can cause serious illness.

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 conditions 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 your symptoms get better.

Parotid tumors

Learn about symptoms and diagnosis of parotid gland tumors. Find out how operations, such as parotidectomy, can treat parotid tumors and parotid cancers.

Partial anomalous pulmonary venous return

In this heart problem present at birth, some of the blood vessels of the lungs connect to the wrong places in the heart. Learn when treatment is needed.

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

This pain at the front of the knee is more common in people who run and who play sports that involve running and jumping.

Patent ductus arteriosus (PDA)

Learn about symptoms, causes and treatment of this common — and treatable — heart problem 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

Understand this condition that can cause your child's breathing to become repeatedly blocked during sleep — either partially or completely.

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.

Pelvic organ prolapse

Learn about treatment choices for this condition, including surgical and nonsurgical options.

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

A dull or burning pain in the stomach could be a peptic ulcer. Find out more about this common, treatable digestive condition.

Pericardial effusion

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

Pericarditis

Inflammation of the tissue surrounding the heart can cause sharp chest pain and other symptoms. 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)

This common blood flow condition can cause leg pain when walking. Lifestyle changes and medicines can help, but sometimes surgery is needed.

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 about these growths that form in or near nerves connecting to the spinal cord. Surgery is the most common 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

Learn about the causes, symptoms and treatment of peritonitis.

Persistent depressive disorder

This type of depression may cause you to feel sad and empty and to lose interest in life. You may feel like a failure. These feelings may last years.

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 an injury causes a concussion.

Personality disorders

A person with this mental health condition thinks, acts and behaves in a rigid pattern that's not healthy. It's hard to understand and relate to others.

Pet allergy

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

Peyronie disease

Understand what causes bent and painful erections and learn what 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, which usually is not cancer.

Pilonidal cyst

Learn about causes, symptoms and treatments of this painful condition that usually affects the skin above the tailbone in people who sit for long periods.

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. Treatments include surgery, radiation therapy and chemotherapy.

Pink eye (conjunctivitis)

This highly contagious eye condition can be itchy and uncomfortable. But much like the common cold, it rarely requires medicine 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 growths that develop in the pituitary gland.

Pityriasis rosea

Learn more about the symptoms, causes and treatment of this large rash common among teens and young adults.

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 rare, potentially fatal disease that's usually passed on by fleas.

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

A general term for lung swelling and irritation, it's often caused by breathing in irritants. The swelling can cause trouble breathing and a dry 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 affects the nervous system. Severe disease can lead to paralysis, trouble breathing and sometimes death.

Polycystic kidney disease

Learn how treatments and lifestyle changes might help reduce kidney damage from this disease.

Polycystic ovary syndrome (PCOS)

Polycystic ovaries, hormone imbalance and irregular periods are telltale signs and symptoms of polycystic ovary syndrome. Find out about 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 the symptoms, causes and treatment for this condition, in which too much amniotic fluid builds up 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 aneurysm

Learn more about this lower extremity aneurysm that occurs in the wall of an artery located behind the knee.

Popliteal artery entrapment syndrome

Calf pain cramping your style during a workout? Know the signs and symptoms of popliteal artery entrapment syndrome.

Porphyria

This group of disorders results from a buildup of natural chemicals in the body that affect the nervous system and skin. Learn how to avoid symptom triggers.

Post-polio syndrome

This syndrome causes a number of potentially serious symptoms that appear decades after the polio virus.

Post-traumatic stress disorder (PTSD)

This mental health condition, which is caused by being part of or witnessing a terrifying event, leads to symptoms that include 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)

In this pelvic floor disorder, the rectum presses against weakened tissues and bulges into the vagina. Learn about the symptoms and treatments.

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 what can cause children's bodies to begin changing into adult bodies 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

Here's what you need to know about caring for a premature baby and the possible health problems of a preterm birth.

Premature ejaculation

Understand what may cause ejaculation to happen earlier than wanted during sex. Also learn how to treat 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 medicine in a way not intended by the prescriber 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 recognition and treatment may help prevent complications.

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. It causes muscle weakness primarily in the legs, arms and tongue.

Primary ovarian insufficiency

This condition, also called premature ovarian failure, happens in women under age 40. Hormone therapy can lessen 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

This genetic disorder is extremely rare and progressive. It causes children to age rapidly, beginning in their first two years of life.

Progressive supranuclear palsy

Learn about this brain condition that affects your 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

This disease mimics gout, causing sudden, painful swelling in one or more joints. Treatments can reduce the pain and improve joint function.

Pseudomembranous colitis

This inflammatory colon condition is usually caused by the bacterium Clostridioides 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

This life-threatening heart condition that's present at birth 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 the symptoms and how it's treated.

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 the symptoms and how it’s treated.

Pulmonary edema

Get more information about the causes of this potentially life-threatening lung condition and learn how to treat and prevent it.

Pulmonary embolism

A blood clot blocks and stops blood flow to an artery in the lung. Often the clot starts in a leg and travels to the lung.

Pulmonary fibrosis

Thickened and scarred lung tissue makes it hard for the lungs to work well. Symptoms are shortness of breath that worsens, cough, tiredness and weight loss.

Pulmonary hypertension

This lung condition makes the heart work harder and become weak. Changes in genes and some medicines and diseases can cause it. Know if you're at risk.

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.

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 the body, mainly fingers and toes, to feel cold and numb and possibly change 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

Learn about the symptoms, causes and prevention of this cancer that starts in the rectum. Treatments include surgery, radiation therapy and chemotherapy.

Rectal prolapse

This rare condition happens when the rectum slips outside of the anus. Find out about symptoms and treatment.

Rectovaginal fistula

This open tunnel connects the rectum and vagina, allowing gas or stool to pass into the vagina. Learn about rectovaginal 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 can be symptoms of this condition. 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 about the causes and treatment of this rare but serious condition causing swelling in the liver and brain.

Rhabdomyosarcoma

This rare soft tissue cancer affects children more often than adults. Treatment may include surgery, chemotherapy and radiation therapy.

Rheumatic fever

Learn about this 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.

Rosacea

Learn about the symptoms, skin care tips and medicines for this common skin condition of the face that causes flushing and spider veins.

Roseola

Learn about the causes of and home-care tips for this common viral infection that often affects children by age 2, causing a high fever followed by a rash.

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 regurgitating and reswallowing food. Behavioral therapy and medicine 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

Learn about the causes, complications and diagnosis of this indentation on the lower back present at birth in some babies.

Sacroiliitis

This joint inflammation can cause pain in the buttocks or lower back. The pain can go down one or both legs.

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 contagious 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 bacterial infection that causes a red rash, sore throat and high fever.

Schizoaffective disorder

This mental health condition includes schizophrenia symptoms, such as delusions and hallucinations, and mood disorder symptoms, such as depression and mania.

Schizoid personality disorder

People with this mental health condition do not want to be with others. They stay away from social activities. They're limited in how they express emotions.

Schizophrenia

This mental condition can lead to hallucinations, delusions, and very disordered thinking and behavior. It can make daily living hard, but it's treatable.

Schizotypal personality disorder

This condition includes odd or eccentric thinking and behavior, few close relationships, and great distrust of others. Treatment can make symptoms better.

Schwannoma

Learn about the diagnosis and treatment of this usually benign, slow-growing tumor that begins in peripheral nerve cells.

Schwannomatosis

This rare conditions causes slow-growing tumors on nerves, including on the nerve in the ear that carries sound information to the brain.

Sciatica

Pressure on the sciatic nerve can cause pain and often numbness down a leg. Self-care measures might help.

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

Sclerosing mesenteritis is a rare condition that may lead to blockage in the small intestine. Learn about treatment at Mayo Clinic.

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

Scorpion stings are painful but rarely life-threatening. Young children and older adults are most at risk of serious complications.

Scrotal masses

Lumps in the scrotum have various causes. Even painless lumps should be checked promptly by a health care professional.

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 the different types of seizures and what causes them. Also find out what to do if you see someone having a seizure.

Selective IgA deficiency

A lack of the disease-fighting antibody called immunoglobulin A (IgA) may cause frequent infections or serious complications.

Self-injury/cutting

Deliberately hurting your own body, such as by cutting or burning, is a harmful way to cope with emotional pain, intense anger and frustration.

Separation anxiety disorder

This is 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 symptoms of STDs and what you can do to prevent them, along with the treatments 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

This infection of the intestine causes diarrhea. Learn the symptoms, treatments and ways to help prevent it.

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 symptoms, causes, treatment and vaccine prevention of this painful condition affecting the nerves.

Short bowel syndrome

This digestive condition happens when part of the small intestine is missing or damaged, 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)

These are times of screaming or crying, intense fear, and sometimes waving arms and legs during sleep. The person often sits up in bed, looking scared.

Sleepwalking

People who get up and walk around while sleeping may not need treatment. But if it happens often, it could be a sleep disorder that needs treatment.

Small bowel cancer

This type of 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 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 usually the treatment.

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

These are extreme fears of objects or situations that pose little or no danger. There is no reason for these fears, but you stay away from these things.

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

Learn about this condition in which an unborn baby's spine and spinal cord don't form properly. Surgery during pregnancy may be a treatment option.

Spinal arteriovenous malformation (AVM)

Learn about how this rare blood vessel condition can affect the spinal cord.

Spinal cord injury

Learn what may happen after the 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

This condition narrows the amount of space within the spine. This can squeeze the nerves that travel through the spine. Surgery is sometimes needed.

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

This common skin cancer usually looks like a bump or a scaly sore. Learn about symptoms and treatment options, including freezing, lasers and surgery.

Stage 4 prostate cancer

Find out about diagnosis and treatment of this 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.

Stomach cancer

Stomach cancer, which is also called gastric cancer, is cancer that begins in the stomach. Learn about symptoms, causes, detection and treatments.

Stomach polyps

These masses of cells that form on your stomach lining usually don't cause symptoms. Learn what causes them and when to be concerned.

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

Movement such as coughing, laughing and running can cause urine to leak for people with this condition. Learn about treatments 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 condition that involves problems with rhythm and flow when speaking.

Stye (sty)

A stye (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

This medical emergency involves sudden loss of all heart activity. Learn how fast, appropriate care may help prevent death.

Sudden infant death syndrome (SIDS)

Learn about the unexplained death of a young baby who seems healthy.

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 rash that is an allergic reaction to sunlight.

Sunburn

Learn more about how UV rays harm your skin and what you can do for symptom sunburn relief and how to protect yourself from sun exposure.

Supraventricular tachycardia

SVT is a heart rhythm disorder that causes a very fast or erratic heartbeat. The heart may beat more than 150 times a minute. Know the symptoms and when it's treated.

Suspicious breast lumps

Most of these growths aren't cancer, but you should still get them checked promptly.

Sweating and body odor

Learn more about the causes, treatment and self-care of this skin condition. Unusual changes may mean a medical problem.

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

Learn more about the symptoms, treatment and prevention of this itchy rash that usually affects people swimming in freshwater lakes.

Swollen knee

This condition can be caused by trauma, overuse injuries, or an underlying disease or condition. A fluid sample from the knee may be needed for diagnosis.

Swollen lymph nodes

Learn more about swollen lymph nodes, including possible causes and treatments your doctor may recommend.

Synovial sarcoma

This rare type of cancer tends to occur near large joints, mainly the knee, in young adults. The main treatment is surgery.

Syphilis

Understand how this infectious disease spreads, what you can do to prevent it 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 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, 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

Tapeworms in the intestines usually cause mild disease. Immature tapeworms, called larval cysts, can cause serious disease in other parts of the body.

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. They can trigger a variety of symptoms such as odd feelings, fear and unresponsiveness.

Tendinitis

Repetitive activities and weekend warrior exercise can bother tendons, causing pain and swelling.

Tennis elbow

Repeated motion of the wrist and arm often cause this condition. It affects athletes and nonathletes. Learn how to prevent and treat it.

Tension headache

These common headaches can be triggered by stress. Healthy habits and medicines can help manage them.

Testicular cancer

Learn about cancer that starts in the testicles. Treatments include surgery, chemotherapy and radiation therapy.

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

These four heart problems present at birth change how blood flows through the body. Know the symptoms and treatment.

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 conditions is caused by pressure on the blood vessels or nerves between the collarbone and rib. The pressure can cause pain and numbness.

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 cancer

Learn how doctors use innovative operations, such as transoral robotic surgery, and radiation technology, including protons, for tongue cancer treatment.

Tongue-tie (ankyloglossia)

In this condition present at birth, a band of tissue (lingual frenulum) tethers the tongue to the floor of the mouth, restricting the range of motion.

Tonic-clonic (grand mal) seizure

Learn about this type of seizure that can cause convulsions. Also know how to help if you see someone having one.

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 condition, 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

Learn about symptoms, causes, treatment and prevention of this parasitic infection that can cause severe disease.

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 short bout of stroke-like symptoms doesn't cause permanent damage. But it 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)

In this mental health condition, people can't resist urges to pull out hair from their body. They do this often. Therapy may help reduce or stop urges.

Tricuspid atresia

Learn how this congenital heart 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 nerve condition that can jolt areas on the face with electric-shock-like pain.

Trigger finger

In this condition, a finger gets stuck in a bent position and may straighten suddenly with a snap. It happens most often in women over the age of 50.

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 congenital 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 prevention and treatment of this disease that causes serious illness around the world.

Tuberous sclerosis

This uncommon genetic disorder causes tumors that are not cancer. These tumors are unexpected overgrowths of tissue in different parts of the body.

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 main problem in diabetes. Learn about lifestyle changes to lower the risk and treatments to manage type 2 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 bacterial infection.

Ulcerative colitis

This type of inflammatory bowel disease affects the innermost lining of your digestive tract. Learn about available treatments for this often exhausting condition.

Ulnar wrist pain

Ulnar wrist pain occurs on the side of your wrist opposite your thumb. The pain can become severe enough to prevent you from doing simple tasks.

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 the usual 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, called the urethra, can limit urine flow and cause a number 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)

Learn the symptoms that may occur if there's an infection in the urinary tract. Also find out what can cause a UTI and how the infection is treated.

Urine color

Foods and medicines can change the color of urine. But a color change also could be a sign of disease.

Uterine fibroids

Learn about these common noncancerous growths and what to do if you have symptoms such as heavy menstrual bleeding.

Uterine polyps

Tissue growths inside the uterus can cause abnormal uterine bleeding or infertility. Learn about 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 the symptoms of this rare type of cancer. Treatments for cancer of the vagina include surgery, radiation therapy and chemotherapy.

Vaginal fistula

Learn about this unusual opening that forms between the vagina and another organ.

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 lines or cords to develop under the skin. Learn self-care steps to take and what treatments there are.

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 symptoms of VFib and what actions to take to save a life.

Ventricular septal defect (VSD)

In this heart problem present at birth, there is a hole between the two lower heart chambers. Know the symptoms and when surgery is needed.

Ventricular tachycardia

This rapid heart rate can be a medical emergency. Know the warning symptoms and how it's treated.

Vertebral tumor

Learn about these tumors that grow in the bones of the spine, causing pain and weakening the spinal column. Find out about diagnosis and treatment.

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 that happens when nerve signals that control the voice box are interrupted.

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

Learn about pain, burning and irritation of the vaginal area that doesn’t have a clear cause. Then find out how to get relief.

Waldenstrom macroglobulinemia

Learn about this rare type of white blood cell cancer. Treatments include chemotherapy, targeted therapy, immunotherapy and bone marrow transplant.

Wet macular degeneration

Blurred vision or blind spots could be a sign of this chronic eye disorder. Recognizing the warning signs could save your vision.

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

This common neck injury often is 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

Progress in the diagnosis and treatment of this kidney cancer have greatly improved the outlook for children with the condition.

Wilson's disease

This inherited disease causes copper to build up in vital organs, especially the liver, brain and eyes. It's treatable when caught early.

Wolff-Parkinson-White (WPW) syndrome

This heart condition present at birth causes a fast heartbeat. Rarely, it can cause sudden cardiac death. Know the symptoms and how it's treated.

Wrinkles

These lines in the skin are a natural part of aging that's also affected by sun exposure and smoking. Learn about prevention tips and treatment options.

Wrist pain

Wrist pain can be caused by many types of problems, ranging from sprains to arthritis. An accurate diagnosis is crucial to determine the proper treatment.

X-linked agammaglobulinemia

This genetic disease weakens the immune system, mainly in males, and leads to having infections often.

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.

Yips

Learn about what causes these involuntary wrist spasms that often frustrate golfers.

Zenker's diverticulum

Find out the symptoms of this condition, how it causes a bulge to form in the tube that connects the throat to the stomach and treatments.

Zollinger-Ellison syndrome

In this rare disease, tumors in the digestive tract cause excess production of a certain hormone. High levels of this hormone increase stomach acid, leading to peptic ulcers.