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 not treated.

Symptoms of peritonitis include:

• Swelling of the abdomen, which may feel hard (rigid).
• Severe pain and tenderness in the abdomen that becomes worse with moving, coughing, or pressing on the abdomen. The pain sometimes reaches into the shoulder.
• Nausea and vomiting.
• A rapid pulse.
• Chills and fever.
• Rapid breathing.

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.