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Quick Facts

Kidney Infection


The Manual's Editorial Staff

Last full review/revision Jul 2021| Content last modified Jul 2021
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What are kidney infections?

Your kidneys are the 2 bean-shaped organs that filter waste products out of your blood and make urine. Sometimes a kidney gets infected by bacteria.

  • Kidney infections are usually caused by the spread of bacteria up your urinary tract to your kidneys

  • A kidney infection usually causes chills, fever, and back pain

  • Kidney infections are more common in women than in men

  • Most kidney infections can be cured with antibiotics

The Urinary Tract

The Urinary Tract

What causes kidney infections?

Most kidney infections are caused by bacteria that normally live in your large intestine. The bacteria get into your kidneys from the outside by traveling up your urinary tract:

  • First, bacteria get in your urethra (the tube that carries urine from your bladder out of your body)

  • Then the bacteria travel up to your bladder

  • From the bladder, bacteria can move up to your kidneys through your ureters (the tubes that connect your kidneys with your bladder)

You're more likely to get kidney infections:

What are the symptoms of a kidney infection?

  • Sudden chills and fever

  • Pain in your lower back

  • Feeling sick to your stomach

People over 60 or 70 years old may have:

  • Confusion

  • Fever

  • An infection of the bloodstream

How can doctors tell if I have a kidney infection?

Your doctor can tell if you have a kidney infection based on:

  • Your symptoms

  • Testing your urine

Your doctor may do blood tests to see if the infection has spread to the bloodstream.

Your doctor may also do imaging tests (CT scan or ultrasound) of your kidneys and urinary tract. The imaging tests are to look for a blockage and other abnormalities that might have caused the kidney infection. You may need imaging tests if you:

  • Still have fever after taking antibiotics for 3 days

  • Often get kidney infections

  • Have a blood test that shows you have kidney damage

How do doctors treat kidney infections?

Your doctor will:

  • Give you antibiotics for 5 to 14 days

  • Take another urine sample shortly after you finish your antibiotics to make sure the infection is gone

You may need to stay at the hospital to get antibiotics directly into your vein for a few days if you:

After you leave the hospital, you will take antibiotics at home.

How can I prevent kidney infections?

If you often get kidney infections, your doctor may have you regularly take a small dose of antibiotics.

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