Boots WebMD Partners in Health
Return To Boots

Kidney infection symptoms

Kidney infections are known medically as pyelonephritis and can cause considerable pain and discomfort.

Kidney infections are usually caused by bladder infections spreading up from the bladder into a kidney or both kidneys.

Always seek medical advice for a kidney infection - as without treatment it can result in lasting damage to the kidneys.

Symptoms of kidney infection

Kidney infection symptoms can come on over some days - or a matter of hours.

Symptoms may include:

A child with a kidney infection may also show signs of:

  • Being irritable
  • Blood in pee
  • Smelly pee
  • Wetting the bed after being dry
  • Not growing at the usual rate if there is a long-term infection.

As well as the kidney infection symptoms, there may also be a bladder infection, cystitis or urethra infection in a child or adult. Symptoms of these infections may include:

  • Pain when peeing, burning feeling
  • An urge to get to the toilet quickly to pee
  • A feeling that the bladder is not fully empty after using the toilet
  • Blood in pee
  • Smelly or cloudy pee
  • Lower abdomen pain.

Kidney infection causes

Bacteria cause kidney infections, usually this is E. coli bacteria. The infection is thought to spread from the bottom (anus) through the penis or vagina area to the urethra tubes, bladder and kidneys.

Kidney infections are more likely to affect women and girls because of the risk of spreading infection when wiping the bottom.

In rare cases the bacteria can spread through the blood if a person's immune system is weakened by a health condition or cancer treatment.

It isn't always known why a person gets a kidney infection, but the chances are higher with:

  • Kidney stones or blockages
  • Enlarged prostate, prostate gland infection in men ( prostatitis)
  • Having urinary tract abnormalities
  • Having problems emptying the bladder completely
  • Use of a catheter to drain urine
  • Having sex, including anal sex
  • Pregnancy
  • Being a victim of female genital mutilation (FGM).

Kidney infection diagnosis

A doctor will diagnose a kidney infection based on the symptoms - especially fever and pain around the sides - the person's medical history and a physical examination.

A urine test may be arranged to check for infection, but this won't tell the doctor where in the urinary tract, including the kidney, the infection is.

Further tests may be arranged, or a referral to a specialist, if the infection isn't helped with treatment, if symptoms worsen quickly, or if there is a risk of complications.

Hospital scans to check the kidneys include:

  • Ultrasound
  • CT scan
  • Isotope scan - where special dye is injected before X-rays are taken to get a better image.

WebMD Medical Reference

Stay informed

Sign up for BootsWebMD's free newsletters.
Sign Up Now!

Popular slideshows & tools on BootsWebMD

woman blowing nose
How to tell the difference
smiling baby
Causes and remedies
bowl of soup
Small changes that lead to weight loss
boy looking at broccoli
Simple tips for feeding fussy eaters
cold sore
How to cope with cold sores
boy coughing
Treatments for cold and fever
bain illustration
Best foods for your brain
bucket with cleaning supplies in it
Cleaning for a healthy home
avacado on whole wheat crackers
Plenty to choose from
woman looking at hair
What your hair says about your health