What is peritonitis?

The peritoneum is the thin tissue that lines the inside of your abdomen (belly) and covers the abdominal organs. Peritonitis is the term for inflammation of the peritoneum. Usually, an infection causes peritonitis. An injury or certain diseases also can cause it. It is important to evaluate the cause of peritonitis right away. Left untreated for too long, some forms of peritonitis can cause other serious health problems.

What causes peritonitis?

Infectious agents including, but not limited to, bacteria and fungi causes peritonitis. Sometimes the infection begins in the peritoneum. More often, the infection spreads from another area of the body.

Some of the most common reasons infection could spread to the peritoneum include:

  • Burst appendix.
  • Stomach ulcer.
  • Inflammation of the pancreas (pancreatitis).
  • Severe abdominal injury such as a knife wound.
  • Infection after abdominal surgery.
  • Digestive conditions such as diverticulitis or Crohn's disease.
  • Infection can also translocate from the gut in certain conditions such as liver failure.

What are the symptoms of peritonitis?

Different people experience different peritonitis symptoms. The most common symptoms are:

  • Severe pain in the abdomen that gets worse when you move.
  • Nausea and vomiting.
  • Fever.
  • Abdomen that is swollen or tender to the touch.
  • Passing smaller amounts of stool or change in stool habits.
  • Unexplained weight loss.

Last reviewed by a Cleveland Clinic medical professional on 05/29/2018.


  • National Health Service. Peritonitis. Accessed 5/30/2018.

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