Loperamide is an antidiarrheal drug that acts as an opioid agonist in the gut but does not cross the blood-brain barrier. It works by inhibiting the release of acetylcholine and prostaglandins, reducing peristalsis and increasing intestinal transit time. This favors water and electrolyte absorption. Loperamide is also used to reduce anal sphincter incontinence and urgency. It is effective for treating mild to moderate diarrhea, diarrhea associated with inflammatory bowel disease, and irritable bowel syndrome with predominant diarrhea. As an opioid restricted to the gut, loperamide has no analgesic effects and no potential for addiction.