Kidney infection (pyelonephritis) is a type of urinary tract infection (UTI) that generally begins in your urethra or bladder and travels to one or both of your kidneys.
A kidney infection requires prompt medical attention. If not treated properly, a kidney infection can permanently damage your kidneys or the bacteria can spread to your bloodstream and cause a life-threatening infection.
Kidney infection treatment, which usually includes antibiotics, might require hospitalization.
Signs and symptoms of a kidney infection might include:
Make an appointment with your doctor if you have worrisome signs or symptoms. If you're being treated for a urinary tract infection but your signs and symptoms aren't improving, make an appointment.
Severe kidney infection can lead to life-threatening complications. Seek immediate medical attention if you have kidney infection symptoms combined with bloody urine or nausea and vomiting.
Bacteria that enter your urinary tract through the tube that carries urine from your body (urethra) can multiply and travel to your kidneys. This is the most common cause of kidney infections.
Bacteria from an infection elsewhere in your body also can spread through your bloodstream to your kidneys. Although it's unusual to develop a kidney infection, it can happen — for instance, if you have an artificial joint or heart valve that becomes infected.
Rarely, kidney infection results after kidney surgery.
Factors that increase your risk of a kidney infection include:
Being female. The urethra is shorter in women than it is in men, which makes it easier for bacteria to travel from outside the body to the bladder. The nearness of the urethra to the vagina and anus also creates more opportunities for bacteria to enter the bladder.
Once in the bladder, an infection can spread to the kidneys. Pregnant women are at even higher risk of a kidney infection.
If left untreated, a kidney infection can lead to potentially serious complications, such as:
Reduce your risk of kidney infection by taking steps to prevent urinary tract infections. Women, in particular, may reduce their risk of urinary tract infections if they:
To confirm that you have a kidney infection, you'll likely be asked to provide a urine sample to test for bacteria, blood or pus in your urine. Your doctor might also take a blood sample for a culture — a lab test that checks for bacteria or other organisms in your blood.
Other tests might include an ultrasound, CT scan or a type of X-ray called a voiding cystourethrogram. A voiding cystourethrogram involves injecting a contrast dye to take X-rays of the bladder when full and while urinating.
Antibiotics are the first line of treatment for kidney infections. Which drugs you use and for how long depend on your health and the bacteria found in your urine tests.
Usually, the signs and symptoms of a kidney infection begin to clear up within a few days of treatment. But you might need to continue antibiotics for a week or longer. Take the entire course of antibiotics recommended by your doctor even after you feel better.
Your doctor might recommend a repeat urine culture to ensure the infection has cleared. If the infection is still present, you'll need to take another course of antibiotics.
If your kidney infection is severe, your doctor might admit you to the hospital. Treatment might include antibiotics and fluids that you receive through a vein in your arm (intravenously). How long you'll stay in the hospital depends on the severity of your condition.
An underlying medical problem such as a misshapen urinary tract can cause you to get repeated kidney infections. In that case, you might be referred to a kidney specialist (nephrologist) or urinary surgeon (urologist) for an evaluation. You might need surgery to repair a structural abnormality.
To reduce discomfort while you recover from a kidney infection, you might:
You'll likely start by seeing your family doctor or a general practitioner. If your doctor suspects your infection has spread to your kidneys, you might be referred to a doctor who treats conditions that affect the urinary tract (urologist).
When you make the appointment, ask if there's anything you need to do in advance, such as restrict your diet for certain tests.
Make a list of:
Take a family member or friend along, if possible, to help you remember the information you're given.
For kidney infection, questions to ask your doctor include:
Don't hesitate to ask other questions.
Your doctor is likely to ask you questions, such as:
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