Multi-DOSE Oral Ondansetron for Pediatric Acute GastroEnteritis

Inclusion Criteria: * Willingness to comply with all study procedures and availability for the duration of the study. * Diagnosis of acute intestinal infectious process (as defined by the protocol) confirmed. by the treating physician. * Age 6 months to 17.99 years. * Presence of ≥ 3 episodes of vomiting in the preceding 24-hour period. * Duration of vomiting and/or diarrheal symptoms \< 72 hours. * A minimum of 1 episode of vomiting within 6 hours of the screening process performed by the research team. * A minimum of 1 dose of ondansetron (oral or intravenous) provided during the current emergency department visit. Exclusion Criteria: * Bilious or bloody vomit during current illness. * Known hypersensitivity to ondansetron or any serotonin receptor antagonist (e.g. palonosetron, dolasetron, granisetron). * Known allergic reaction to components of ondansetron (citric acid, sodium benzoate, sodium citrate dihydrate, and strawberry flavor, sorbitol) or the placebo medication (methylparaben, glycerin, citric acid, potassium sorbate, sorbitol, strawberry flavor). * History or family history (first degree relative) of prolonged QT syndrome. * Presence of complex congenital heart disease. * History or family history (first degree relative) of cardiac arrhythmia. * Concomitant use (within the past 48 hours) of any of the following: QTc prolonging medications, medications known to cause torsades de pointes, medications that cause electrolyte abnormalities, serotonergic or neurole…