Ondansetron to Prevent Oral Rehydration Failure in Children With Cholera

This Phase IIa randomized controlled trial will evaluate whether a single oral dose of ondansetron can reduce oral rehydration failure in children and adolescents with suspected or confirmed cholera and active vomiting. Approximately 120 participants aged 6 months to 17 years with no or some dehydration will be randomized 1:1 to receive standard cholera care alone or standard care plus oral ondansetron 0.15 mg/kg, up to a maximum dose of 8 mg. The primary outcome is oral rehydration failure within 6 hours, defined as initiation of clinically necessary, unplanned intravenous fluids. Secondary outcomes include vomiting frequency, oral rehydration solution intake, intravenous fluid volume, time to clinical rehydration, length of stay, and safety outcomes.

Inclusion Criteria: * Age 6 months to 17 years * Suspected or confirmed cholera * Active vomiting, defined as at least 1 episode within the preceding 4 hours * No dehydration or some dehydration according to WHO/GTFCC criteria * Parent/guardian able to provide informed consent * Assent from children aged 7 years or older, when applicable Exclusion Criteria: * Severe dehydration or shock requiring immediate intravenous rehydration * Known allergy or contraindication to ondansetron * Congenital long QT syndrome or known arrhythmia * Concurrent use of QT-prolonging medications * Inability to tolerate oral medication * Lack of parent/guardian informed consent or required child assent