CRD summary: This review concluded that there is insufficient evidence to recommend the routine use of ondansetron for vomiting during acute gastroenteritis in children, despite some clinical benefits. There were considerable limitations to this review but, overall, the authors' conclusion appears reasonable and the recommendations for future research seem justified.

CRD commentary: The review addressed a clear question in terms of the participants, interventions, outcomes and study design. Several databases were searched, the search terms and dates were reported, and no language restrictions were applied, thus limiting the possibility of publication bias. However, the authors did not formally assess publication bias because of the small number of included studies. Methods were used to minimise reviewer error and bias in the study selection and data extraction processes. Validity was assessed using published criteria. There was evidence of clinical heterogeneity between the studies. For example, one review included participants from 1 month to 22 years of age, making it difficult to assess the effectiveness of the intervention only in children. The dosage and route of administration, as well as outcome definitions, also varied considerably between the studies. Where there was clinical and statistical heterogeneity, combining the studies in a meta-analysis might not have been appropriate. There were considerable limitations to this review but, overall, the authors' cautious conclusion appears reasonable and the recommendations for future research seem justified.