Kidney infection

A kidney infection is a painful, unpleasant illness usually caused by bacteria travelling from your bladder into one or both of your kidneys.

Symptoms of kidney infection 

A kidney infection is more serious than cystitis, a common infection of the bladder that makes urinating (when you pee) painful. The symptoms of a kidney infection usually develop quite quickly over a few hours or days.

Common symptoms include:

  • pain and discomfort in your side, lower back or around your genitals
  • high temperature (it may reach 39.5C or 103.1F)
  • shivering or chills
  • feeling very weak or tired
  • loss of appetite
  • feeling sick or being sick
  • diarrhoea

You may have other symptoms if you also have cystitis or urethritis (an infection of the urethra). These additional symptoms may include:

  • pain or a burning sensation during urination
  • needing to urinate very often or urgently
  • feeling that you're unable to urinate fully
  • blood in your urine
  • cloudy or foul smelling urine
  • pain in your lower abdomen


Children with a kidney infection may also have additional symptoms, such as:

Causes of a kidney infection 

A kidney infection (pyelonephritis) usually happens when bacteria infect your kidneys. The bacteria are usually a type called E. coli, which live in your bowel.

Treating a kidney infection 

Kidney infections are quite rare. They can happen at any age, but are much more common in women.

Most people with a kidney infection can be treated at home with a course of antibiotics, and possibly painkillers as well.

When to see your GP 

You should contact your GP if you:

  • have a fever
  • have persistent tummy, lower back or genital pain
  • notice a change to your usual pattern of urination

If you have blood in your urine, you should always see your GP so the cause can be investigated.

Contact your GP immediately or out of hours GP service if you think your child may have a kidney infection.

Help with preventing infections

You can reduce your chances of developing a kidney infection by keeping your bladder and urethra (the tube that allows urine to pass out of your body) free from bacteria.

You can help prevent an infection by:

  • drinking plenty of fluids
  • keeping your genitals clean
  • treating any constipation

Toilet tips

To help keep your urinary tract free from bacteria:

  • go to the toilet as soon as you feel the need to urinate (to pee), rather than holding it in
  • wipe from front to back after going to the toilet
  • practice good hygiene by washing your genitals every day and before having sex
  • empty your bladder after having sex
  • if you're a woman, avoid ‘hovering’ over a toilet seat as it can result in your bladder not being fully emptied


The information on this page has been adapted from original content from the NHS website.

For further information see terms and conditions.

This page was reviewed April 2018

This page is due for review January 2021

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