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by Savitsky D
(Infection, Kidney; Pyelonephritis)


Kidney infections may occur in one or both kidneys. The kidneys remove waste from the body through urine. They also balance the water and mineral content in the blood. An infection can cause pain and swelling which may stop the kidneys from working as needed.

Normal Anatomy of the Kidney
Copyright © Nucleus Medical Media, Inc.


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.

Risk Factors

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 abdomen, 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


Your doctor will ask about your symptoms and medical history. A physical exam will also be done. A sample of your urine will be studied for blood and pus. Sometimes the urine will be tested to look for the exact type of bacteria.

A UTI may be suspected based on the symptoms alone. It may not be important to know exactly where the infection is. Images of the kidney may be needed for severe symptoms. Options include:


A kidney infection can be treated with antibiotics. It is important to take all of the medication as recommended. A hospital stay may be needed with a severe kidney infection. This will allow the antibiotics to be delivered through IV.

If the shape of the urinary tract was causing the infection other help may be needed. This may include a surgery to fix the problem.

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


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:  . Updated January 26, 2017. Accessed September 7, 2017.

Kidney infection (pyelonephritis). National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: Accessed August 17, 2015.

Uncomplicated urinary tract infection (UTI) (pyelonephritis and cystitis). DynaMed Plus website. Available at: Updated March 15, 2017. Accessed November 30, 2017.

Urinary tract infection (UTI) in men. EBSCO DynaMed Plus website. Available at:  . Updated January 26, 2017. Accessed September 7, 2017.

Revision Information

  • Reviewer: EBSCO Medical Review Board Adrienne Carmack, MD
  • Review Date: 09/2018
  • Update Date: 03/02/2018