Peritonitis is inflammation of the peritoneum, the thin layer of tissue that lines the inside of the abdomen (tummy).

It is caused by an infection, which can rapidly spread around the body.

Peritonitis is regarded a medical emergency and requires immediate treatment. 

Signs of peritonitis often develop quickly and can include:

  • sudden abdominal pain that becomes more severe
  • nausea (feeling sick)
  • a lack of appetite
  • a high temperature (fever) of 38°C (100.4°F) or above
  • not passing any urine or passing less than normal

Read more about the symptoms of peritonitis.

When to get medical help

Sudden abdominal pain that gradually gets worse is usually a sign of a potentially serious infection or illness.

If you have this type of pain, contact your GP immediately. If this is not possible, call NHS 111 or your local out-of-hours service.

Why peritonitis happens

Peritonitis is caused by a bacterial or fungal infection that either develops directly in the peritoneum or spreads from another part of the body.

Most cases of peritonitis are the result of infection or injury to another part of the body, such as:

Less commonly, an infection develops directly within the peritoneum due to:

Read more about the causes of peritonitis.

How peritonitis is treated

Peritonitis is a serious condition that needs to be diagnosed and treated quickly to prevent possibly fatal complications developing, so you will usually be admitted to hospital for tests and treatment.

The underlying infection will be treated with injections of antibiotics or antifungal medication, depending on the cause of the infection.

In some cases, surgery may be required to repair damage to the peritoneum or to treat the underlying cause of the infection.

Read more about diagnosing peritonitis and treating peritonitis.


Peritonitis can be fatal, despite the best efforts of medical staff. This is often due to the infection spreading through the bloodstream to the major organs (septic shock).

It's estimated that about 1 in every 10 people with peritonitis due to bowel perforation (a hole that develops in the bowel wall) will die, although this can vary considerably depending on what caused the condition, your age, and your general health.

Deaths are less common for peritonitis related to cirrhosis or kidney dialysis, but it is still a serious condition.

Read more about the possible complications of peritonitis.

© Crown Copyright 2009

This site uses cookies. By continuing to browse this site you are agreeing to our use of cookies. Find out more here.