This article reviews several recent studies on effects of medications on the colon. Nonsteroidal anti-inflammatory drug-associated diseases, including colitis, stercoral perforations of the colon, and complications of diverticular disease are presented. The toxic effects to the colon of South African tribal enemas and methamphetamines are detailed. Inhibition of colonic prostaglandin synthesis by sulindac with a reduction in polyps in patients with polyposis coli is noted. Other studies discussed include information about the following: colonic prostaglandin levels after laxative use, mechanism of action of simethicone, the role of different fiber diets in the generation of colonic short-chain fatty acids, fiber in infant formulas, the role of dietary calcium in reducing fecal water cytotoxicity, short-chain fatty acid therapy, and polypeptide diets. New reports of Dieulafoy's lesions and some other vascular abnormalities of the colon and two studies on colonic injury from radiation are discussed.