Ondansetron effective for gastroenteritis with vomiting

Clinical Question

Is ondansetron safe and effective for dehydrated children with gastroenteritis?

Bottom Line

Ondansetron (Zofran) given to children who are mildly to moderately dehydrated because of diarrhea and vomiting improves their ability to comply with oral rehydration and reduces the need for intravenous hydration. (LOE = 1b)


Freedman SB, Adler M, Seshadri R, Powell EC. Oral ondansetron for gastroenteritis in a pediatric emergency department. N Engl J Med 2006;354:1698-1705.  [PMID:16625009]

Study Design

Randomized controlled trial (double-blinded)






Emergency department


Although oral rehydration is the treatment of choice for children with gastroenteritis, it can be a challenge when the child can't keep anything down. This leads to overuse of intravenous hydration, particularly given the time pressures in the emergency department. These authors considered for inclusion any mildly to moderately dehydrated child who'd had at least 1 episode of diarrhea and 1 episode of vomiting in the previous 4 hours. Those with a body weight of less than 8 kg (17 pounds), who were severely dehydrated using standardized symptoms (eg, clammy or cool skin, very dry mucosa, no tears, moderate tachycardia, no urine for at least 6 hours, limp, and lethargic), and those with significant comorbodities were excluded. Of the 243 children asked to enroll, 215 underwent randomization (allocation concealed) to ondansetron or placebo. The dose of ondansetron was 2 mg for children who weighed between 8 kg and 15 kg, 4 mg for those who weighed 15 kg to 30 kg, and 8 mg for those who weighed more than 30 kg. The dose was repeated if children vomited within 15 minutes of taking the medicine. The mean age of children was 28 months, 57% were male, and they had a mean of 9 episodes of vomiting and 6 episodes of diarrhea in the previous 24 hours. Groups were similar at baseline, and analysis was by intention to treat. Children receiving ondansetron were less likely to vomit while being given liquids (14% vs 35%; P = .001; number needed to treat [NNT] = 5), had fewer vomiting episodes (0.18 vs 0.65; P < .001), and were less likely to require intravenous rehydration (14% vs 31%; P = .003; NNT = 5). There was no difference in the number of children requiring hospitalization or the percentage returning to the emergency department. The drug was well tolerated, although there was a mean of 0.9 additional episodes of diarrhea for children randomized to ondansetron..