Ondansetron (Zofran) had been FDA approved for two decades and highly effective for nausea and vomiting. It is indicated for:
Prevention of nausea and vomiting associated with highly emetogenic cancer chemotherapy, including cisplatin ≥ 50 mg/m2.
Prevention of nausea and vomiting associated with initial and repeat courses of moderately emetogenic cancer chemotherapy.
Prevention of nausea and vomiting associated with radiotherapy in patients receiving either total body irradiation, single high-dose fraction to the abdomen, or daily fractions to the abdomen.
Prevention of postoperative nausea and/or vomiting.
Because it used to be very expensive, Zofran used to be used primarily for chemotherapy. As the cost dropped (now under a $1 a dose), it is came to be used in other situations. More an more commonly it is being used empirically in nursing homes. The drug is so effective, that some physicians consider using it as needed easier on the elderly patient than finding out the reason for nausea in these patients.
This strategy needs more data to be considered well supported. Zofran is not a completely innocuous drug. The U.S. Food and Drug Administration (FDA) recenlty informed healthcare professionals and the public that preliminary results from a recently completed clinical study suggest that a 32 mg single intravenous dose of ondansetron (Zofran, ondansetron hydrochloride, and generics) may affect the electrical activity of the heart (QT interval prolongation), which could pre-dispose patients to develop an abnormal and potentially fatal heart rhythm known as Torsades de Pointes. Consequenlty, GlaxoSmithKline (GSK) has announced changes to the Zofran drug label to remove the 32 mg single intravenous dose. While the 8 mg dose is presumably free of this complications, one remains uncomfortable about empiric use of Zofran in any clinical situation in which it has not been studied, and such a strategy needs to be validated with clinical trials
For Professional version and other elgitimate uses of Zofran see here