Used to prevent nausea and vomiting caused by cancer chemotherapy, radiation therapy, and surgery. It works by blocking the action of serotonin, a natural substance in the body that can trigger vomiting. Commonly given before and after treatments to patients at high risk of nausea, especially with highly emetogenic chemotherapy. Also used off-label for managing nausea in pregnancy and gastroenteritis when other treatments fail. Available in oral, intravenous, and orally disintegrating forms for flexible dosing in various clinical settings.