Pyelonephritis is an infection of one or both of your kidneys. Anyone can get a kidney infection but it's most common in women and people who have an abnormal kidney
You have two kidneys, which 'clean' your blood by filtering out water and waste products to make urine. Urine is stored in your bladder and then passed out of your body through your urethra. This is the tube that carries urine from your bladder and out of your body.
Pyelonephritis is a bacterial infection of your kidneys. The infection can be either acute or chronic. Acute and chronic refer to how long the condition lasts, rather than how severe it is. This factsheet will focus on acute kidney infection, which tends to come on quickly but should go within a couple of weeks.
The symptoms of an acute kidney infection often develop quickly over a few hours or a day and may include:
If you have any of these symptoms, contact your GP.
Around one in three women who get an acute kidney infection have symptoms of a bladder infection as well. This is also called cystitis, or a lower urinary tract infection (UTI). See our frequently asked questions for more information about UTIs.
An acute kidney infection can sometimes cause complications including:
You're more likely to develop complications if you:
A kidney infection is usually caused by bacteria such as Escherichia coli (E. coli), which live in your bowel. The bacteria can get into your urinary tract if they spread from your anus to your urethra. The bacteria can enter your urethra and travel up into your bladder and will usually cause a lower UTI or cystitis. The bacteria can then travel up one or both of the tubes that connect your bladder to your kidneys (ureters) and cause a kidney infection.
You can also spread the bacteria when you have sex, as bacteria can enter your urethra. Bacteria and viruses can also be carried in your blood from other parts of your body to your kidney.
Women get more kidney infections than men. This is partly because the urethra is much shorter in women than in men. There is less distance for the bacteria to travel to the bladder.
You're also more likely to develop a kidney infection if you:
Your GP will ask about your symptoms and examine you. He or she may also ask you about your medical history. Your GP will ask you to provide a urine sample. He or she will usually do a 'dipstick' test to confirm if you have a urinary infection. Your GP may send your urine sample to a laboratory to find out which type of bacteria is causing the infection.
In you have a severe kidney infection, your GP may recommend you go into hospital for further tests and treatment. Other tests may include:
It’s important to drink enough fluids to prevent yourself from getting dehydrated. Make sure you get plenty of rest too.
If you need pain relief, you can take over-the-counter painkillers such as paracetamol. Always read the patient information leaflet that comes with your medicine and if you have any questions, ask your pharmacist for advice.
Your GP will usually prescribe antibiotics if he or she suspects that you have a kidney infection. It’s important to take the full course of antibiotics, even if your symptoms clear up before you finish them. Your symptoms should start to improve within a day or so. But if they get worse or you don't feel any better within 48 hours of starting treatment, contact your GP.
You may need hospital treatment if you’re:
In hospital, you may have a drip inserted into a vein in your hand or arm to give you fluids and antibiotics.
You may need to have surgery if tests show that you have an obstruction (such as a kidney stone) in your ureters or kidneys.
If you have a kidney infection when you're pregnant, it may lead to complications, such as:
If your GP suspects you have a kidney infection, he or she may send you for tests and treatment in hospital.
If you often get a kidney infection or a UTI, your GP may advise you to take a low dose of antibiotics every day. How long you need to take them for will depend on your personal circumstances.
You can also develop a kidney infection from cystitis. If you get cystitis, try self-help measures or get prompt treatment to cure the condition. This will reduce the risk of the infection spreading to your kidneys.
Reviewed by Rachael Mayfield-Blake, Bupa Health Information Team, March 2014.
For answers to frequently asked questions on this topic, see FAQs.
For sources and links to further information, see Resources.
This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.
Bupa Private GP Services