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.
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.
About 1 in 2,000 people get a kidney infection every year in the U.S.
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.
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Symptoms of a kidney infection include:
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:
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.
Risk factors for kidney infections include:
Sometimes, kidney infections can lead to life-threatening complications, especially in people with a weakened immune system or other underlying health issues. These include:
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.
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.
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.
Your provider may prescribe one or a combination of antibiotics to treat a kidney infection. They may include:
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.
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:
The outlook for kidney infections is usually good. You may need to be treated in the hospital if:
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.
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.
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.
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.
See a healthcare provider if you’re having trouble peeing or if you notice changes in your pee (like blood or cloudiness).
Go to the nearest emergency room if you have any signs of severe dehydration or serious illness, including:
It might be helpful to ask your healthcare provider:
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.
Last reviewed by a Cleveland Clinic medical professional on 01/31/2023.
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