Based on current evidence, bulking agents are not more effective than placebo at improving global irritable bowel syndrome (IBS)symptoms, although they may increase stool frequency in large doses. Tricyclic antidepressants are more effective than placebo for patients with diarrhea-predominant IBS. Imodium is more effective than placebo at improving stool consistency and decreasing stool frequency in patients with IBS, and it may be an important component for treating diarrhea-predominant IBS. Antispasmodics agents available in the United States are not more effective than placebo for treating IBS, although the studies are small and poorly designed. There are no randomized controlled trials examining the efficacy of laxatives for managing IBS. Tegaserod is more effective than placebo at improving global IBS symptoms in women with nondiarrhea-predominant IBS. Alosetron is more effective than placebo in women with diarrhea-predominant IBS, although its use should be limited to patients who have failed conventional therapy because of its adverse event profile.