Peritonitis is an infection of the lining of the abdominal wall (peritoneum) caused by bacteria or irritating substances. Peritonitis causes pain and swelling in the abdomen and can be very serious if it is not treated.

Symptoms of peritonitis include:

• Swelling of the belly, which may feel hard (rigid).
• Severe pain and tenderness in the belly that may get worse with moving, coughing, or pressing on the belly. The pain sometimes goes up into the shoulder.
• Fever and chills.
• A fast pulse.
• Rapid breathing.
• Confusion or feeling less alert.
• Nausea and vomiting.
• Diarrhea.

A person with these symptoms requires immediate medical attention. Treatment typically involves surgery and antibiotics. Without treatment, the illness gets worse rapidly and can become life-threatening.