Used primarily to prevent nausea and vomiting caused by chemotherapy, radiation therapy, or surgery. It works by blocking serotonin receptors in the brain and gut, which are involved in triggering the vomiting reflex. Commonly administered before cancer treatments to improve patient comfort and tolerance to therapy. Also used off-label in some cases for postoperative nausea and in managing certain types of diarrhea-predominant irritable bowel syndrome due to its action on gut receptors.