Zofran tablets, syrup and injection all contain the active ingredient
ondansetron hydrochloride dihydrate, which is a type
of medicine called a 5HT3 antagonist. (NB. Ondansetron is also available without a brand name, ie as the generic medicine.) Ondansetron is used to prevent and treat nausea and vomiting that can be caused by chemotherapy or radiotherapy treatment for cancer, or by surgery.
Vomiting is controlled by an area of the brain called the vomiting centre.