Take Zofran (Ondansetron Hydrochloride Tablets) (Ondansetron Hydrochloride Tablets) exactly as it was prescribed by your doctor. This medicine can be taken with or without food. Take the Zofran (Ondansetron Hydrochloride Tablets) with a full glass of water. Do not swallow the tablet whole. Allow it to dissolve in your mouth without chewing. To prevent nausea from chemotherapy, take this medication by mouth usually within 30 minutes before treatment begins. To prevent nausea from radiation treatment, take this medication by mouth 1 to 2 hours before the start of your treatment. To prevent nausea after surgery, take ondansetron by mouth 1 hour before the start of surgery.

Take the missed dose as soon as possible. Skip the missed dose if it is time for your next scheduled dose. Don't take extra medicine to make up the missed dose.