Diverticulitis is the inflammation or infection of small pouches (diverticula) that form in the lining of the digestive system, most commonly in the lower section of the large intestine. 

It is a common condition, particularly in people over the age of 60, with around half of all people in this age-group in the US developing diverticula, according to figures from the American Society for Gastrointestinal Endoscopy. Diverticulitis develops when these diverticula become inflammed or infected.

Diverticulitis can cause severe abdominal pain, which may persist for several days; abdominal tenderness; fever; fatigue; nausea; and constipation or diarrhea. Risk factors include being over 60 years of age, lack of exercise, obesity, smoking, and certain medication, such as ibuprofen or steroids.

Treatment for diverticulitis depends on the severity of the condition. If mild, it may be treated with antibiotics, over-the-counter pain medication and a liquid diet. In more severe cases, physicians may recommend intravenous antibiotics or surgery. Drug classes used to treat diverticulitis include anaerobicides or penicillinase-sensitive penicillin antibiotics, and over-the-counter pain-relieving medication, such as acetaminophen.