(Infection, Kidney; Pyelonephritis)
Kidney infections may occur in one or both kidneys. An infection can cause pain and swelling which may stop the kidneys from working as needed. The kidneys remove waste and pass it out of the body as urine. They also balance the water and mineral content in the blood.
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Kidney infections are caused by a bacteria. The bacteria often enters the lower part of the urinary tract first. It can then grow and cause a UTI. If the UTI is left untreated it can spread up into the kidneys. Most UTIs are caused by a bacteria that normally live in the colon or vagina. It gets passed to the opening of the urinary tract during everyday activities.
Problems with the shape of the urinary tract may also slow or block the flow of urine. This may make it easier for infections to develop.
Women have a higher risk of kidney infection than men. Factors that may increase your chance of a kidney infection include:
- Being sexually active
- Use of spermicide
- New sexual partner
- Bladder infection
Some conditions may increase the chance of a kidney infection include:
Symptoms of kidney infection may include:
- Pain in the belly, lower back, side, or groin
- Frequent urination
- Urgent urination that produces only a small amount of urine
- Sensation of a full bladder—even after urination
- Burning pain with urination
- Fever and chills
- Nausea and vomiting
- Pus and blood in the urine
- Loss of appetite
The doctor will ask about symptoms and past health. A physical exam will also be done. A sample of urine will be studied for blood and pus. Sometimes the urine will be tested to look for the exact type of bacteria.
A kidney infection may be suspected based on the symptoms alone. Images of the kidney may be needed for repeat infections. They can help to show problems with the structure of kidneys.
A kidney infection can be treated with antibiotics. It is important to take all of the antibiotic as recommended. A hospital stay may be needed with a severe kidney infection. This will allow the antibiotics to be delivered through IV.
Poorly treated or untreated kidney infections can lead to:
- A serious, life-threatening infection that spreads throughout the body— sepsis
- Chronic infection
- Scarring or permanent damage that can lead to severe kidney disease
Some kidney infections are caused by a problem with kidney structure. Surgery may be needed to fix the problem.
To help decrease the risk of a urinary tract infection (UTI):
- Empty your bladder completely and drink a full glass of water after having sex.
- Drink plenty of fluids throughout the day.
National Kidney Foundation
Urology Care Foundation
The Kidney Foundation of Canada
Women's Health Matters
Complicated urinary tract infection (UTI). EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T114928/Complicated-urinary-tract-infection-UTI. Accessed September 7, 2020.
Kidney infection (pyelonephritis). National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: https://www.niddk.nih.gov/health-information/urologic-diseases/kidney-infection-pyelonephritis. Accessed September 7, 2020.
Uncomplicated urinary tract infection (UTI) (pyelonephritis and cystitis). DynaMed website. Available at: https://www.dynamed.com/topics/dmp~AN~T116894/Uncomplicated-urinary-tract-infection-UTI-pyelonephritis-and-cystitis. Accessed September 7, 2020.
Urinary tract infection (UTI) in men. EBSCO DynaMed website. Available at: http://www.dynamed.com/topics/dmp~AN~T904748/Urinary-tract-infection-UTI-in-men. Accessed September 7, 2020.
Last reviewed September 2020 by EBSCO Medical Review Board Last Updated: 3/2/2021