Among the drug therapies used for the irritable bowel syndrome, smooth-muscle relaxants are beneficial when abdominal pain is the predominant symptom. The efficacy of bulking agents has not been established. Loperamide is effective for diarrhea, and data on psychotropic agents are inconclusive. Evidence for 5-hydroxytryptamine–receptor antagonists seems favorable.
Ann Intern Med. 2000;133(2):136-147. doi:10.7326/0003-4819-133-2-200007180-00013