Most kidney infections are treated successfully without complications, although some people may develop further problems.

Complications of a kidney infection are rare, but you're more likely to develop them if you:

Some of the main complications of kidney infections are outlined below.

Kidney abscess

A kidney abscess is a rare, but serious, complication of a kidney infection, where pus develops inside the tissue of the kidney.

You're thought to be most at risk of developing a kidney abscess if you have diabetes.

The symptoms of a kidney abscess are similar to those of a kidney infection. The most common are:

  • a high temperature of 38C (100.4F) or above
  • chills
  • abdominal pain
  • loss of appetite
  • pain when passing urine

Kidney abscesses are potentially serious because the bacteria inside the abscess can spread to other parts of your body, such as your bloodstream or lungs, and can be fatal.

Smaller abscesses can usually be treated with antibiotics through a drip. Surgery is usually required for larger abscesses. This involves draining the pus out of the abscess using a needle that's inserted into the kidney.

Blood poisoning

Blood poisoning (also called sepsis) is another rare, but potentially fatal, complication of a kidney infection. It happens when bacteria spreads from the kidneys into the bloodstream. Once bacteria are in your blood, the infection can spread to any part of your body, including all of the major organs.

In someone with a kidney infection, the symptoms of blood poisoning include:

  • low blood pressure, which makes you feel dizzy when you stand up
  • confusion or disorientation
  • excessive sweating
  • uncontrollable shaking or shivering
  • high temperature or lower body temperature than usual (under 36C, or 96.8F)
  • pale skin
  • rapid heartbeat
  • breathlessness

Blood poisoning is a medical emergency that usually requires admission to a hospital intensive care unit (ICU) while antibiotics are used to fight the infection.

If you're taking certain medications for diabetes, such as metformin or angiotensin-converting enzyme (ACE) inhibitors, they may be temporarily withdrawn until you recover. This is because they can cause kidney damage during an episode of blood poisoning.

Severe infection

Another rare, but potentially fatal, complication of a kidney infection is a condition called emphysematous pyelonephritis (EPN).

EPN is a severe infection, where the tissues of the kidneys are rapidly destroyed and the bacteria causing the infection begin to release a toxic gas, which builds up inside the kidneys.

The exact cause of EPN is unclear, but almost all cases are in people with diabetes.

The usual treatment is emergency surgery to remove some, or all, of the affected kidney. It's possible to live a full and active life with only one kidney.

Kidney failure

In very rare cases, a kidney infection can cause severe kidney damage that results in kidney failure. This is when the kidneys stop working properly.

Kidney failure is potentially fatal, but it can be treated with dialysis or a kidney transplant.

Other problems

A kidney infection can also cause other complications, including high blood pressure (hypertension) or premature labour and birth.

Page last reviewed: 19/12/2014
Next review due: 19/12/2017