Acute colitis related to penicillin and penicillin derivatives

5 cases of acute transient colitis associated with the ingestion of ampicillin, an ampicillin derivative, and penicillin are discussed. The clinical presentation, course, and radiographic and sigmoidoscopic findings are distinct from those in pseudomembranous colitis. The colonic changes may be related to an allergic reaction in the intestine which results primarily in transient ischaemia. The presenting symptom is blood diarrhoea, and barium enema is the most productive diagnostic examination.