This study may have immediate impact on patient management. Based on the results, it will be discovered if oral ondansetron plays a role in reducing the need for intravenous rehydration in children with gastroenteritis in Pakistan. As ondansetron is now available in generic formulations, and is relatively inexpensive, it is anticipated that if this study is positive, ondansetron will be considered for inclusion in the WHO - gastroenteritis care package. This could ultimately lead to a decrease in the need for intravenous rehydration in children in countries such as Pakistan.