Multidose Ondansetron Reduces Gastroenteritis Severity in Children After ED Visit: New Study Finds

The primary outcome measured was a modified Vesikari score of 9 or higher during the seven days following enrollment. Results showed that only 5.1% of children in the ondansetron group experienced moderate-to-severe gastroenteritis compared to 12.5% in the placebo group—an absolute risk reduction of 7.4 percentage points.

The adjusted odds ratio was 0.50 (95% CI, 0.40 to 0.60), confirming ondansetron’s effectiveness. Interestingly, the median duration of vomiting and presence of vomiting didn’t differ significantly between the groups. However, ondansetron significantly reduced the total number of vomiting episodes within 48 hours (adjusted rate ratio, 0.76; 95% CI, 0.67 to 0.87).

There were no major differences in unscheduled healthcare visits, IV fluid use, or adverse events between the two groups. These findings support the short-term use of oral ondansetron beyond the ED setting to improve symptom control in pediatric patients, a practice that previously lacked robust data. The study was funded by the Canadian Institutes of Health Research and other pediatric research institutions.

Reference:

New England Journal of Medicine, Multidose Ondansetron after ED Visits in Children with Gastroenteritis, July 2025.