ABSTRACT: Irritable bowel syndrome (IBS) is characterized by abdominal pain or discomfort, bloating, and constipation or diarrhea; the pain is typically relieved by defecation. The diagnosis is not one of exclusion; it can be made based on the answers to a few key questions and the absence of "alarm" symptoms. Fiber therapy, the elimination of particular foods, and regulation of bowel function can help relieve symptoms. Tegaserod or polyethylene glycol can be used to treat IBS with constipation. Loperamide and alosetron are of benefit in IBS with diarrhea (although the latter carries a small risk of ischemic colitis). Low-dose tricyclic antidepressants may be used to treat the abdominal pain associated with IBS. Probiotic therapy or rifaximin may help reduce bloating. Psychological therapies seem to improve well-being in patients with IBS.