Kidney Infection

Last Updated October 2020 | This article was created by familydoctor.org editorial staff and reviewed by Beth Oller, MD

What is a kidney infection?

A kidney infection results when bacteria or a virus get into one or both of your kidneys. The medical name for it is pyelonephritis.

Your kidneys filter blood, remove waste, and produce urine. They’re part of the urinary tract. This group of organs includes your kidneys, ureters, bladder, and urethra. Kidneys are shaped like beans about the size of your fist. They’re located on either side of your spine, below your rib cage.

Symptoms of a kidney infection

Common symptoms of a kidney infection include:

  • Fever
  • Pain in your back, side, or groin
  • Chills
  • Nausea and/or vomiting
  • Frequent urination
  • A feeling of needing to urinate, even though you just did
  • Painful, burning, and/or frequent urination
  • Cloudy or bad-smelling urine
  • Blood or pus in your urine

Symptoms can vary by age. Babies and older people might not have the common symptoms. Instead, they may have slurred speech, dizziness, or confusion. Get medical care right away if you have any of these symptoms.

What causes a kidney infection?

The main cause of a kidney infection is Escherichia coli (E. coli). This bacterium can travel to your kidney(s) from somewhere else in your urinary tract, such as your bladder. It’s very common to get a kidney infection if you already have a urinary tract infection (UTI). Women tend to get kidney infections and UTIs more often than men. This is due to the shape of female anatomy.

How is a kidney infection diagnosed?

It’s important to detect and treat a kidney infection right away. Your doctor will ask about your symptoms. They will probably ask you to give a urine and/or blood sample, too. In some cases, your doctor might order other tests. These include an ultrasound, an X-ray, a computerized tomography (CT) scans, or a magnetic resonance imaging (MRI). These tests will provide pictures of your urinary tract organs.

Can a kidney infection be prevented or avoided?

You can help prevent a kidney infection or UTI if you:

  • Drink enough water
  • Urinate after sex
  • Don’t hold urine in
  • Avoid using douches and scented products in your genital area
  • Wipe your genital area from front to back (for women)

Although anyone can get a kidney infection, some people are at greater risk. You’re more likely to get a kidney infection if you:

  • Are pregnant
  • Have diabetes
  • Already have a UTI
  • Have an oddly-shaped urinary tract
  • Have a kidney stone
  • Have an enlarged prostate (for men)
  • Have a weakened immune system
  • Have to use a catheter to remove urine from your bladder
  • Have vesicoureteral reflux (VUR). This is a condition where urine can flow up or down your ureters

Kidney infection treatment

Antibiotics are the main treatment for kidney infections. There are different kinds. Your doctor will decide which type is best for you. Most of the time, antibiotics are provided as a pill. In severe cases of kidney infection, you may need an IV (a catheter in your arm) to get the medicine. You also may need to stay in the hospital. This is more common if you’re dehydrated and/or older.

You always should follow your doctor’s instructions about your medicine. It could take several weeks to get rid of the infection, even if your symptoms go away. Your doctor might perform a follow-up test to confirm the infection is gone. They also might prescribe other medicine or treatment to address the cause or a related issue.

Living with a kidney infection

Most people who have a kidney infection recover. You can get kidney infections more than once. Talk to your doctor about how to help prevent future infections.

Questions to ask your doctor

  • Why do you think I got a kidney infection?
  • How much water should I drink every day to stay hydrated?
  • What is the best medicine for me to treat my kidney infection?
  • Once I start medicine, how long will it take for my symptoms to go away?
  • Since I’ve had one kidney infection, am I likely to get another?
  • What is the risk of a kidney infection leading to chronic kidney disease?