Category Archives: Paeds

Paediatric Gastroenteritis

vomitWarning.  This is occasionally devolves into a bit of a rant, however it’s a rant with a sound evidence base.

Can we please give kids with gastroenteritis some anti-emetic?  If you happen to be reading this in the US, Canada, New Zealand or Austrailia where standard practice is a little different, I apologise.  Let me give you some background.

In the UK children who get gastroenteritis and come to ED get assessed, usually because parents have been trying and failing to hydrate them.  We tend to give them an oral fluid challenge.  Usually ORS at 5 or 10mls ever 5 or 10 minutes.  They get a full history, examination, their hydration status is documented and usually we wait for them to urinate.  If they don’t vomit, urinate (and the urine dip is okay), we shout hurrah, fist bump (or would but we are British) and send the parent on their way with a prescription or advice to get or make ORS, and to continue with the little and often amount of fluid required.

If they ‘fail’ this challenge by vomiting we are often forced to admit them, and continue with the cycle until they wee.  Paediatric admission units have one or two of these children on the go at any one time, and we just keep ploughing on until the child stops vomiting, or they get dehydrated enough to require NG or IV fluid.

For some strange reasons in this group of patients there is a lot of resistance to trying an oral fluid challenge with an anti-emetic.

I have yet to hear a coherent reason as to why this but the commonest one is that it ‘might mask symptoms’.  I can’t understand why this could be the case, as anti-emetics work by blocking receptors in the CTZ.  I’m not sure how this would stop vomiting secondary to some other serious disease process.  If someone has a closed head injury like a subdural they are going to continue to vomit no matter what you do, and will have other signs.  Similarly if a child has a metabolic disorder, their BM is going to be low (or really ‘freakin’ high), or there are going to be other clues in the history.  Also I’m suggesting giving a dose of anti-emetic to kids that we have diagnosed with acute gastroenteritis, which implies that you have assessed the patient, taken a history and examined them.  The anti-emetic the literature seems to favour is ondansetron.

So will we miss something? 

Looking for evidence for this is tricky, as it’s hard to prove a negative, especially when the ‘things we might miss’ are very rare metabolic disorders.  There is some research that backs me up.

Sturm, Jesse J., et al. “Ondansetron use in the pediatric emergency department and effects on hospitalization and return rates: are we masking alternative diagnoses?.” Annals of emergency medicine 55.5 (2010): 415-422.

Sturm conducted a retrospective review of visits to paediatric EDs in Atlanta, USA, between 2005 and 2007.  34 117 charts were reviewed, and ondansetron was used for 19857 patients.  They found that there was no significant change in the diagnosis at discharge between children given ondansetron and those who weren’t, they were also less likely to be admitted.  Children who were given ondansetron were more likely to return, and then be readmitted, but the admission rate globally was less in the ondansetron group than the nothing group.

Okay so it means we probably won’t miss anything but does it actually work?

YES. – NNT is about 5. That’s better than steroids in COPD (NNT 10) and Aspirin in STEMI (NNT 42).

Well the key single RCT was published in the NEJM in 2006, this was a prospective, double blind randomized controlled trial.

P 215 children 6 month – 10 years in the Paeds ED with gastroenteritis AND mild dehydration.
I 1 single dose of orally disintegrating ondansetron
O Primary:Proportion who vomiting while having rehydration


  1. Number of vomits,
  2. Incidence of IV rehydration
  3. Admission rates.
Primary:14% vs 35% RR 0.4 95% CI 0.26-0.61


  1.  0.18 mean vomits Vs 0.65 p<0.0001
  2. 14 % Vs 31% RR 0.46 CI 0.26-0.79 p=0.003
  3. 4% Vs 5% not significant


You can get the study here.

What do these results mean?  Well it looks like the group that were given a single dose of ondansetron we more likely to pass their fluid challenge, less likely to need IV therapy, but were not necessarily more likely to go home.  I like this last result.  I think it means that if a child was still dehydrated, and needed further observation that this was what was happening rather than taking false reassurance from being given a medication.

Children were given 2mg PO ondansetron 8-15kg, 4mg 15-30kg, 8mg if >30kg.

Caveats?  The children participating in the study were assigned a dehydration score by a single rater, which was based on largely clinical, and subjective measures such as skin turgor.  The dehydration score they used is pretty much the same table as exists in paeds textbooks and APLS manuals so seems a reasonable method to use however, it does introduce the potential for bias.  The other concern for me about this study was the number of patients that were excluded prior to randomization, 3067 children were considered but only 243 were asked to enrol, another potential source for bias.

This study on it’s own yields a NNT of 5.  We need to treat 5 children with acute gastroenteritis with ondansetron to stop 1 kid vomiting.

This is all very promising but is there any other data to support it’s use?

I’m glad you asked….

Then a Cochrane review was published in the BMJ in 2012 which looked at the literature from 1980 to 2012.  Ondansetron They found 10 studies and compared ondansetron (oral, and IV) to granestron, dexamethasone, and other antiemetics.  They looked at ondansetron vs placebo for cessation of vomiting, initiation of IV rehydration and hospital admission rates.  Now the review could only find 4 studies looking at the effectiveness of PO Ondansetron vs placebo, but their headline result for cessation of vomiting was RR 1.44 95% CI 1.29-1.61 NNT = 4.  One study was reliable but VERY pro ondansetron and threw the results out a bit, but with that excluded you still got an impress result RR 1.33 9%% CI 1.19- 1.49 NNT =5.  There was no statistically significant difference in hospitalization rates within 72 hours, suggesting that children’s admission might be delayed rather than avoided if you trial them ondansetron.  They did manage to find a reduction in resorting to IV rehydration [RR 0.57 NNT 6].

SO there is good evidence to suggest that it is safe and effective to use oral ondansetron in a vomiting child with gastroenteritis, we will probably decrease length of stay, increase success of oral rehydration, and maybe save some money for the trust.  No one will thank you for it though…

…apart from the kid’s parent, oh and the kid.

Rant ends.



  • Carter, Ben, and Zbys Fedorowicz. “Antiemetic treatment for acute gastroenteritis in children: an updated Cochrane systematic review with meta-analysis and mixed treatment comparison in a Bayesian framework.” BMJ open2.4 (2012).
  • Sturm, Jesse J., et al. “Ondansetron use in the pediatric emergency department and effects on hospitalization and return rates: are we masking alternative diagnoses?.” Annals of emergency medicine 55.5 (2010): 415-422.
  • Freedman, Stephen B., et al. “Oral ondansetron for gastroenteritis in a pediatric emergency department