This medicine contains Ondansetron, which belongs to a group of medicines called anti-emetics, which help to stop you feeling or being sick. Ondansetron is used to treat nausea (feeling sick) and vomiting (being sick) caused by some medical treatments, such as chemotherapy or radiotherapy for cancer (in adults and children). It is also used to prevent nausea and vomiting in patients following an operation (adults only).