Kidney Infection



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:

  • Diabetes
  • Weak immune system
  • Pregnancy
  • Menopause
  • Bladder catheter in place or recently used
  • Neurogenic bladder
  • Renal insufficiency
  • Kidney stones
  • Problems in the urinary tract that slow the flow of urine, such as vesicoureteral reflux or polycystic kidneys
  • History of kidney transplant
  • Tumor



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.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.