Kidney Infection (Pyelonephritis)

Kidney infections are a type of urinary tract infection that usually moves from your bladder to your kidneys. Bacteria are the most common cause. Symptoms include fever, trouble peeing, lower back pain and pain when you pee. Kidney infections are treated with antibiotics.


Symptoms of a kidney infection include fever, chills and pain in your lower back. Peeing may be painful, bloody or cloudy.
A kidney infection is more likely than a lower UTI to suddenly make you feel sick, give you a fever or cause pain in your lower back or side.

What is a kidney infection (pyelonephritis)?

A kidney infection (pyelonephritis) is a type of urinary tract infection (UTI). Bacteria cause it when they move from another part of your body, like your bladder, up to one or both of your kidneys.

Kidney infections can be more serious than lower UTIs. See a healthcare provider if you have symptoms of a kidney infection.

How common are kidney infections?

About 1 in 2,000 people get a kidney infection every year in the U.S.

How can you tell the difference between a kidney infection and a UTI?

A kidney infection is a type of urinary tract infection (UTI). But when people say “UTI,” they often mean a lower urinary tract infection, or infection of their bladder or urethra. A lower UTI and a kidney infection can have similar symptoms, but a kidney infection is more likely to suddenly make you feel sick, give you a fever or cause pain in your lower back or side.


Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

Symptoms and Causes

What are the signs and symptoms of a kidney infection?

Symptoms of a kidney infection include:

What causes kidney infections?

Bacterial infections are the most common cause of kidney infections. Viruses can cause them, too, but it’s rare in people who are healthy. Some types of bacteria that cause kidney infections include:

  • E. coli.
  • Proteus mirabilis.
  • Enterobacter.
  • Staphylococcus.

How do you get a kidney infection?

Your kidneys make pee (urine) to get rid of waste. The pee moves through tubes (ureters) to your bladder (a pouch that holds your pee until you go to the bathroom). From there, it moves through another tube (urethra) to leave your body. This usually cleans out any bacteria or other germs with it.

Sometimes, bacteria can move upwards into your body and infect parts of your urinary tract, including your urethra, bladder (cystitis) or ureters. From there, they can move into one or both of your kidneys, causing a kidney infection. Bacteria that get into your blood from another part of your body can also infect your kidneys.

What are the risk factors for kidney infection?

Risk factors for kidney infections include:

  • Blockage. Anything that keeps you from emptying the pee out of your urinary tract can allow bacteria to grow and back up into your kidneys. This includes kidney stones, enlarged prostate and uterine prolapse. Pressure on your bladder during pregnancy can also increase your risk.
  • Vesicoureteral reflux. This is a condition where pee goes the wrong way and backs up from your bladder.
  • Conditions that put you at increased risk for infections. These include diabetes, HIV and being on immunosuppressive medications.
  • Your anatomy. Women and people assigned female at birth and people who don’t have a penis have a shorter urethra, which makes it easier for bacteria to move up to their bladder and kidneys.

What are the complications of a kidney infection?

Sometimes, kidney infections can lead to life-threatening complications, especially in people with a weakened immune system or other underlying health issues. These include:

  • Emphysematous pyelonephritis. This is a condition where bacteria start destroying parts of your kidneys and create gas. It’s most common in people with diabetes.
  • Renal papillary necrosis. This is a condition that damages your kidneys.

Diagnosis and Tests

How is a kidney infection diagnosed?

A healthcare provider diagnoses a kidney infection by reviewing your symptoms and testing your pee for signs of infection (urinalysis). They may also test your blood and get images of your kidneys with a CT scan or renal ultrasound.

How can you tell if you have a kidney infection?

Only a healthcare provider can diagnose you with a kidney infection. If you have symptoms of a urinary tract infection with fever and pain in your side, you might have a kidney infection.

Management and Treatment

How is a kidney infection treated?

Healthcare providers treat kidney infections with antibiotics. You’ll have to take antibiotics for at least 14 days. If you’re very sick or if you aren’t getting better with antibiotics, you might need to be treated in the hospital or take antibiotics for longer.

What medications treat kidney infections?

Your provider may prescribe one or a combination of antibiotics to treat a kidney infection. They may include:

  • Trimethoprim-sulfamethoxazole (TMP-SMX).
  • Amoxicillin or augmentin.
  • Ceftriaxone or cephalexin.
  • Ciprofloxacin or levofloxacin.

How soon after treatment for a kidney infection will I feel better?

You should start feeling better within two to three days of starting antibiotics. It may take longer for some people. You need to complete your prescription of antibiotics even if you start to feel better.


Can kidney infections be prevented?

Kidney infections often start as infections in your bladder. Preventing these lower urinary tract infections is the first step in preventing kidney infections. Some ways to prevent infections in all parts of your urinary tract include:

  • Drink plenty of fluids. Talk to your healthcare provider about the amount of water and other fluids they recommend for you each day.
  • Empty your bladder completely. Holding in your pee can help bacteria grow.
  • Pee before and after having sex. This helps remove any bacteria that’s in your urinary tract.
  • Practice good hygiene. Things like showering regularly and changing out of wet or sweaty underwear can help prevent bacteria from getting into your body. After you poop, wipe from front to back. This helps push bacteria in your poop away from openings in your body.

Outlook / Prognosis

What can I expect if I have a kidney infection?

The outlook for kidney infections is usually good. You may need to be treated in the hospital if:

  • You’re very sick or have infections in other places in your body.
  • You have an underlying condition, like a weakened immune system.
  • The infection isn’t getting better with treatment.

How long does a kidney infection last?

With treatment, you can feel better from a kidney infection in a few days (though you need to finish the course of antibiotics). But if your infection is harder to treat, it could last for several weeks.

Can a kidney infection go away by itself?

For some people, lower UTIs can go away on their own, but kidney infections can lead to serious complications if left untreated. Talk to a healthcare provider if you have symptoms of a kidney infection.

What can I do at home for a kidney infection?

Drinking plenty of water and avoiding alcohol and caffeine can help your kidneys while they fight the infection. But you shouldn’t try to cure a kidney infection with a home remedy. Follow your provider’s recommendations for taking any prescribed medications and for how to take care of yourself at home.

Living With

How do I take care of myself?

Drink plenty of fluids and take all of your medication as prescribed. Keep taking antibiotics until you’ve finished your prescription, even if you feel better. Your infection may come back if you stop taking your medication too soon.

When should I see my healthcare provider?

See a healthcare provider if you’re having trouble peeing or if you notice changes in your pee (like blood or cloudiness).

When should I go to ER for a kidney infection?

Go to the nearest emergency room if you have any signs of severe dehydration or serious illness, including:

  • Fever or pain that comes on suddenly.
  • Not peeing or peeing very little.
  • Confusion or mental changes.
  • Severe shortness of breath.

What questions should I ask my doctor?

It might be helpful to ask your healthcare provider:

  • How do I take my medications?
  • What can I do at home to feel better?
  • How can I prevent a kidney infection in the future?

A note from Cleveland Clinic

Kidney infections are rarely serious when treated promptly. Practicing good hygiene and emptying your bladder completely can help prevent UTIs that can move up to your kidneys. If you have an underlying condition that makes you more likely to get an infection, talk to your provider about preventing infections.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 01/31/2023.

Learn more about our editorial process.

Urology 216.444.5600
Kidney Medicine 216.444.6771