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Am Fam Physician. 2012;85(11):1054-1056

Author disclosure: No relevant financial affiliations to disclose.

Clinical Scenario

A five-year-old girl is brought to your clinic by her parents. She has had nausea and vomiting for the past two days, has been unable to keep fluids down, and appears dehydrated. The parents would like to avoid hospitalization, if possible, and are wondering if any medications are safe and effective for controlling her symptoms.

Clinical Question

Should antiemetics be prescribed for vomiting related to acute gastroenteritis in children and adolescents?

Evidence-Based Answer

Ondansetron (Zofran) given orally can reduce rates of vomiting, improve short-term tolerance of oral fluids, and reduce short-term rates of hospital admission and the need for intravenous hydration. Metoclopramide (Reglan) and ondansetron can reduce episodes of vomiting when given intravenously. Dimenhydrinate suppositories given rectally can reduce the time to cessation of vomiting but not overall rates of hospital admission. (Strength of Recommendation: A, based on consistent, good-quality, patient-oriented evidence.)

Cochrane Abstract

Background: Vomiting is a common manifestation of acute gastroenteritis in children and adolescents. When untreated, it can be a hindrance to oral rehydration therapy, which is the cornerstone in the management of acute gastroenteritis. Evidence is needed concerning the safety and effectiveness of antiemetic use for vomiting in acute gastroenteritis in children.

Objectives: To assess the safety and effectiveness of antiemetics on gastroenteritis-induced vomiting in children and adolescents.

Search Strategy: The authors searched the Cochrane Upper Gastrointestinal and Pancreatic Diseases Group Trials Register, comprising references identified from comprehensive electronic database searches and hand searches of relevant journals and abstract books of conferences. The search was rerun and is up to date as of July 20, 2010.

Selection Criteria: Randomized controlled trials comparing antiemetics with placebo or no treatment, in children and adolescents younger than 18 years, for vomiting due to gastroenteritis.

Data Collection and Analysis: Two review authors independently assessed trial quality and extracted data.

Main Results: The authors included seven trials involving 1,020 participants. Mean time to cessation of vomiting in one study was 0.34 days less with dimenhydrinate suppository compared with placebo (P = .036). Pooled data from three studies comparing oral ondansetron with placebo showed: a reduction in the immediate hospital admission rate (risk ratio [RR] = 0.40; number needed to treat [NNT] = 17; 95% confidence interval [CI], 10 to 100) but no difference between the hospitalization rates at 72 hours after discharge from the emergency department; a reduction in intravenous rehydration rates both during the emergency department stay (RR = 0.41; NNT = 5; 95% CI, 4 to 8) and in follow-up to 72 hours after discharge from the emergency department (worst-best scenario for ondansetron; RR = 0.57; NNT = 6; 95% CI, 4 to 13); and an increase in the proportion of patients with cessation of vomiting (RR = 1.34; NNT = 5; 95% CI, 3 to 7). No significant difference was noted in revisit rates or adverse effects, although diarrhea was reported as an adverse effect in four of the five ondansetron studies. In one study the proportion of patients with cessation of vomiting in 24 hours was 58 percent with intravenous ondansetron, 17 percent with placebo, and 33 percent with metoclopramide (P = .039).

Authors' Conclusions: Oral ondansetron increased the proportion of patients who had ceased vomiting and reduced the number needing intravenous rehydration and immediate hospital admission. Intravenous ondansetron reduced hospital admissions and the number of episodes of vomiting. Intravenous metoclopramide reduced episodes of vomiting, and dimenhydrinate rectal suppository reduced the duration of vomiting.

These summaries have been derived from Cochrane reviews published in the Cochrane Database of Systematic Reviews in the Cochrane Library. Their content has, as far as possible, been checked with the authors of the original reviews, but the summaries should not be regarded as an official product of the Cochrane Collaboration; minor editing changes have been made to the text (

Practice Pointers

Acute gastroenteritis accounts for more than 1.5 million outpatient visits and 200,000 hospitalizations each year among children in the United States.1 Although oral rehydration therapy (ORT) has been recommended as a first-line treatment for acute gastroenteritis,1 emergency physicians in the United States use antiemetics more often than ORT.2 A 2009 review found that older antiemetics (e.g., promethazine, prochlorperazine, metoclopramide) have common, potentially dangerous adverse effects when used in children,3 but a guideline from the National Institute for Health and Clinical Excellence in the United Kingdom concluded that “oral ondansetron could increase the success rate with ORT.”4

The authors of this Cochrane review sought to determine the safety and effectiveness of antiemetics for the treatment of vomiting from gastroenteritis in children and adolescents younger than 18 years.5 Six studies that met inclusion criteria assessed the use of ondansetron in the emergency department setting, comparing it with placebo (four trials), with metoclopramide or placebo (one trial), or with dexamethasone or placebo (one trial). A seventh trial assessed the use of dimenhydrinate (rectal suppository) versus placebo in five children's hospitals and six pediatric practices.

Ondansetron given orally reduced rates of hospital admission and intravenous hydration during the emergency department stay, and reduced the need for intravenous hydration when assessed 72 hours after emergency department discharge (number needed to treat = 5 to 6). Oral ondansetron also reduced rates of vomiting and improved tolerance of oral fluids at eight hours. However, there was no evidence that oral ondansetron reduced rates of hospital admission at 72 hours after emergency department discharge, or that it improved emergency department revisit rates or tolerance of oral fluids at 24 hours.

The study comparing intravenous ondansetron with intravenous metoclopramide and placebo found that both medications reduced the number of episodes of vomiting compared with placebo, with intravenous ondanestron being more effective. Intravenous ondansetron and intravenous metoclopramide were associated with an increased risk of diarrhea.

The study of dimenhydrinate given rectally by suppository found that, when compared with placebo, it reduced the time to cessation of vomiting (0.6 versus 0.94 days), the number of episodes of vomiting, and the proportion of patients with vomiting at 18 and 24 hours. However, dimenhydrinate given rectally showed no improvement over placebo in parental satisfaction or rates of hospitalization.

Overall, the interventions studied in this review appeared to be safe, with adverse effects limited primarily to diarrhea, rash, drowsiness, and sedation. No severe adverse effects attributable to the antiemetics studied were reported.

A few cautions are warranted in applying these data to clinical practice. First, because most comparisons assessed in the review were of an antiemetic versus placebo, this Cochrane review did not directly compare the effectiveness of ondansetron and dimenhydrinate. Second, this review did not examine the relative benefits of ORT versus antiemetic medication. However, because ORT was typically started soon after administering study medications, ORT could be considered the equivalent of a “placebo” treatment in this setting (Ben Carter, PhD, Bangor University, United Kingdom, written communication, January 2012). Another Cochrane review found no clinically important differences between ORT and intravenous rehydration therapy.6 ORT is more commonly used for acute gastroenteritis in Canada than in the United States, even though the two countries have similar populations and medical systems.2 Lastly, because the studies included in this review were conducted in emergency departments in the United States, Canada, Turkey, and Venezuela, their results may not be completely generalizable to settings in the developing world. Only the German study of dimenhydrinate assessed the use of an antiemetic in a setting typical of primary care.

Although this review did not assess the relative benefits of antiemetics versus ORT, it provides evidence that the antiemetics ondansetron (given orally or intravenously) and dimenhydrinate (by suppository) improve some short-term clinical outcomes in acute gastroenteritis, and have reasonable safety profiles in children and adolescents.

These are summaries of reviews from the Cochrane Library.

This series is coordinated by Corey D. Fogleman, MD, assistant medical editor.

A collection of Cochrane for Clinicians published in AFP is available at

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