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Kidney infection

Kidney infection

A kidney infection is a type of urinary tract infection (UTI) that usually starts in your urethra or bladder. Find out about the symptoms and treatment.

What is a kidney infection?

A kidney infection (also called pyelonephritis) is a type of urinary tract infection (UTI) that affects women more than men.

The infection usually starts in your urethra or bladder (known as cystitis). Then, bacteria can travel to one or both of your kidneys, causing a kidney infection.

Although kidney infections can be painful and uncomfortable, they’re easy to treat with antibiotics if diagnosed quickly. But if they’re left untreated, they can cause permanent damage to your kidneys.

Kidney infection symptoms

The signs of a kidney infection can come on quite quickly. These might include:

  • Fever
  • Shivering and chills
  • Pain in your back, side or around your genitals
  • Feeling a strong urge to pee
  • Peeing more than usual
  • Burning sensation or pain when you pee
  • Tiredness
  • Nausea and vomiting
  • Blood in your pee
  • Smelly or cloudy urine
  • Pain in your tummy

Children may have a temperature and feel sick. Other symptoms in children include blood in their pee, smelly pee and wetting the bed.

When to see a doctor

If you’re concerned that you, or your child, has a kidney infection, see a doctor as soon as possible. Kidney infections need prompt treatment, and the sooner you receive treatment, the better your chances of a quick recovery.

Always see a doctor if there’s blood in your pee or if you have symptoms of a UTI (like fever and persistent tummy, back or genital pain) that last for a few days or longer.

Kidney infection causes

Kidney infections are generally caused by bacteria from a bladder infection (cystitis) travelling up into the kidneys. But, while cystitis is the most common cause, most people with cystitis don’t get a kidney infection.

Kidney infection diagnosis

If you think you or your child has a UTI, see a doctor or out-of-hours emergency service immediately.

The doctor will assess your symptoms and take a urine test to look for signs of a UTI. This is usually enough to diagnose a kidney infection, but other tests may also be needed, including blood tests, an ultrasound, or a CT scan.

Kidney infection treatment

Antibiotics are generally needed to treat kidney infections. The course usually lasts between seven and 14 days, and you should start to feel better after a couple of days. It’s important to take the full course to make sure the infection clears up properly. Most people recover completely after two weeks.

In addition to antibiotics, you can take painkillers like paracetamol to help reduce pain and fever but avoid anti-inflammatory painkillers (NSAIDs) like ibuprofen unless the doctor recommends them.

Self-care for kidney infections

  • Drink plenty of water to help flush out the bacteria from your kidneys
  • Get plenty of rest
  • Try to empty your bladder fully when you pee

Hospital treatment

You may be referred to the hospital if you’ve got an underlying condition that makes you vulnerable to kidney infections.

Other situations where a doctor may refer you to the hospital include:

  • If you’re male – It’s standard practice to refer men to the hospital because kidney infections are less common in men
  • If you’re female and have had two or more kidney infections
  • If your child has a kidney infection – Most children will be treated in the hospital

Hospital treatment usually involves being given fluids and antibiotics through a drip (a narrow, bendy tube that’s inserted into a vein in the back of your hand or your arm). Doctors will monitor your blood and your urine to check that the infection is clearing up.

Most people respond well to hospital treatment. If there are no complications, they are usually well enough to go home after a few days.

Kidney infection complications

If they’re diagnosed promptly, kidney infections usually clear up with antibiotics. In rare cases, when left untreated, they can cause complications including:

  • Blood poisoning (also known as septicaemia or sepsis) – When the bacteria spreads to your bloodstream
  • Kidney damage – Like scarring or ‘fibrosis’, the primary cause of kidney disease
  • Pregnancy complications – Kidney infections during pregnancy put women at a higher risk of premature birth or having a baby with a low birth weight

Preventing kidney infections

Women are at a much higher risk of getting kidney infections than men. These risks can be reduced by:

  • Drinking lots of fluids, especially water
  • Peeing as soon as you need to
  • Peeing after sexual intercourse to help clear bacteria from the urethra
  • Wiping from front to back to help stop the spread of bacteria to the urethra
  • Avoiding feminine products for the genitals that are perfumed and can cause irritation
Reviewed by:

Dr Rhianna McClymont

Lead GP at Livi

Last updated: