Gastroenteritis

Gastroenteritis is a common disease, usually of viral origin, that inflames the stomach and small intestine. It is characterized by diarrhea and/or vomiting, with or without fever. Most children seeking emergency department (ED) care have no/minimal dehydration. The focus of treatment should be on promoting oral rehydration therapy and minimizing the use of intravenous rehydration.

• While nearly 40% of cases present with isolated vomiting¹ (most commonly caused by norovirus), carefully consider other causes of isolated vomiting in children:
  • Surgical, infectious (e.g., UTI), CNS or metabolic disorders (e.g., DKA)
• Pathogen identification is not routinely required. Send stool for bacterial testing (molecular or culture) in children with bloody diarrhea, diarrhea lasting >5 days, and in returning travelers. Children with isolated diarrhea without vomiting are more likely to have a bacterial etiology.²
• Stool parasite testing has a low yield in the ED; consider testing in children with risk factors (e.g., returning travelers, contact with farm animals, or exposure to untreated water sources).

• Dehydration assessment is the cornerstone of management. The degree of dehydration is categorized since accurately quantifying percent dehydration can be very difficult.
• If a recent weight is available, use it as the gold standard to calculate % weight loss.
• Practitioners with limited experience assessing dehydration in children should use a clinical scale such as the Gorelick Score⁴ or Clinical Dehydration Scale Score⁵ to rule out dehydration. These scores have high sensitivity but low specificity.
• Take time to communicate your evaluation to caregivers/patients as this can be a source of anxiety.

MINIMAL DEHYDRATION – CAN BE MANAGED AT HOME

• Encourage and allow children to drink their preferred fluids & continue an age-appropriate diet.
• If vomiting is present, frequent small amounts of fluid can often be tolerated.
• If vomiting is absent, children should be encouraged to eat a normal diet.

MILD–MODERATE DEHYDRATION – TREAT IN THE ED

• Within 2-4 hours of presentation to the ED. rapidly replace fluid deficit orally with 50-100 mL/kg of:
  • Oral Rehydration Solution (ORS) (e.g., Pedialyte^®, Pediatric Electrolyte^®), and/or
  • Preferred fluids (e.g., electrolyte-containing sports drinks, diluted apple juice, ORS popsicles), and/or
  • Breastfeeding using more frequent and shorter sessions.
• Aim to administer “1-2-3 ounces”:
  • • 6 months – <5 years: 30 mL per 10 minutes
    • 5-10 years: 60 mL per 10 minutes
    • >10 years: 90 mL per 10 minutes
• Administer additional fluids to replace ongoing losses (vomiting and/or diarrhea).
• Observe children in the ED until they are tolerating fluids and demonstrate improved clinical status.
• Nasogastric rehydration with ORS at 50 mL/kg divided over 3 hours is an alternative option.
• Intravenous hydration is rarely needed, does not improve outcomes, and is associated with repeat ED visits.
• Reintroduce solids as soon as possible (e.g., 6 hours after the last vomit episode), but focus should remain on fluid intake.

SEVERE DEHYDRATION

• Administer immediate rehydration with NS or RL 20 mL/kg bolus IV/IO over 10-20 minutes and repeat as needed to restore hemodynamic stability.
  • Often requires ≥ 60 mL/kg, administered as 20 mL/kg boluses, over the first hour
• Measure glucose, electrolytes, and renal function. Treat hypoglycemia if present.
• Reassess vital signs and hydration status before and after each bolus.
• Once child is hemodynamically stable, reintroduce oral fluids and discontinue IV.
  • If unable to adequately perform oral rehydration therapy, start maintenance IV fluids with isotonic/balanced crystalloid including adequate dextrose and potassium as required (e.g., D5NS or D5LR + 20-40 mmol/L KCl).
• Consult Pediatrics/Pediatric Referral Centre for children with significant hypo/hypernatremia.

• Ondansetron is safe, cost-effective and enhances the success of oral rehydration in children with “some” dehydration treated in the ED.⁸
  • Weight-based ondansetron dosing regimen:
    • 8 – 15 kg:2 mg PO
    • >15 – 30 kg:4 mg PO
    • >30 kg:8 mg PO
  • While ondansetron elixir (0.15 mg/kg) can be used in infants 3-6 months of age, it is rarely needed in this age group and should be used only after alternative diagnoses have been excluded.
  • Oral dissolving tablets (ODT) are preferred over regular tablets/liquid formulations due to ease of administration.
  • Providing 2 additional doses of ondansetron to be taken Q8H PRN at home to children with vomiting within the past 6 hours and ≥3 episodes in the past 24 hours improves outcomes.⁹
  • Do not use IV ondansetron due to the risk of QTc prolongation and lack of benefit over the oral route.
  • Do not use dimenhydrinate due to no evidence of benefit reported in clinical trials.
  • Do not use antidiarrheal medications and do not administer antibiotics empirically.

• Perform point-of-care glucose testing in any child with lethargy or altered mental status.
  • If glucose ≤ 2.6 mmol/L: treat with 5 mL/kg D10W IV push and recheck in 5-10 minutes.
  • Alternatively, the hypoglycemia can be treated orally if the child can tolerate ORS or an alternative fluid option, as above.

• Severe dehydration or significant electrolyte abnormalities
• Dehydration and intractable vomiting, oral fluid refusal, or inadequate oral fluid intake
• Worsening diarrhea or dehydration despite adequate volumes of fluid
• Concern for other possible illnesses complicating the clinical course
• Young infant, persistent irritability or drowsiness, progressive symptoms or significant past medical history
• Caregiver requires or would benefit from hospital-based supports to care for child

• Counsel caregivers on care at home and reasons to return to the ED. Parent and family resources related to gastroenteritis can be accessed at trekk.ca/parentsandfamilies.

Thank you to the following content expert who led the development of the Gastroenteritis Bottom Line Recommendations:

Stephen B. Freedman, M.D.C.M., Professor, Department of Pediatrics, Alberta Children’s Hospital and Cumming School of  Medicine, University of Calgary; Alberta Children’s Hospital Research Institute

Thank you to the TREKK Editorial Committee, editor Dr. Sarah Reid (CHEO), CHRIM Parent and Youth Advisory Committee, who  provided editorial support and expertise in the development of this resource.

Thank you as well to Mateja Carevic, TREKK Project Coordinator (University of Manitoba) who coordinated the development  process.

To see our resource development process please visit our website here.

(as cited in the Gastroenteritis Bottom Line Recommendations):

1. Freedman SB, Xie J, Lee BE, et al. Microbial Etiologies and Clinical Characteristics of Children Seeking Emergency  Department Care Due to Vomiting in the Absence of Diarrhea. Clin Infect Dis. 2021;73(8):1414-1423.
2. Tarr GAM, Chui L, Lee BE, Pang XL, Ali S, Nettel-Aguirre A, Vanderkooi OG, Berenger BM, Dickinson J, Tarr PI, Drews S,  MacDonald J, Kim K, Freedman SB. Performance of Stool-testing Recommendations for Acute Gastroenteritis When Used  to Identify Children With 9 Potential Bacterial Enteropathogens. Clin Infect Dis. 2019 Sep 13;69(7):1173-1182. doi:  10.1093/cid/ciy1021. PMID: 30517612; PMCID: PMC7348586.
3. Freedman SB, Vandermeer B, Milne A, Hartling L; Pediatric Emergency Research Canada Gastroenteritis Study Group.  Diagnosing clinically significant dehydration in children with acute gastroenteritis using noninvasive methods: A meta- analysis. Pediatr. 2015 Apr;166(4):908-16. Epub 2015 Jan 29.
4. Gorelick MH, Shaw KN, Murphy KO. Validity and reliability of clinical signs in the diagnosis of dehydration in children.  Pediatr. 1997;99:e6.
5. Friedman JN, Goldman RD, Srivastava R, Parkin PC. Development of a clinical dehydration scale for use in children  between 1 and 36 months of age. J Pediatr. 2004 Aug;145(2):201-7. doi: 10.1016/j.jpeds.2004.05.035. PMID: 15289767.
6. Freedman SB, Ali S, Oleszczuk M, Gouin S, Hartling L. Treatment of acute gastroenteritis in children: An overview of  systematic reviews of interventions commonly used in developed countries. Evidence-based Child Health: A Cochrane  Review Journal. 8(4):1123-1137 (2013).
7. King CK, Glass, R, Bresee JS, Duggan C, Centers for Disease Control and Prevention. Managing acute gastroenteritis among children: Oral rehydration, maintenance and nutritional therapy. MMWR Recomm Rep. 52 (RR-16):1-16(2003).
8. FSB, Adler M, Seshadri R, Powell EC. Oral ondansetron for gastroenteritis in a pediatric emergency department. N Engl J  Med. 2006 Apr 20;354(16):1698-705. doi: 10.1056/NEJMoa055119. PMID: 16625009.
9. Freedman SB, Williamson-Urquhart S, Plint AC, Dixon A, Beer D, Joubert G, Pechlivanoglou P, Finkelstein Y, Heath A,  Zhang JZ, Wallace A, Offringa M; Pediatric Emergency Research Canada Innovative Clinical Trials Study Group. Multidose  ondansetron after emergency visits in children with gastroenteritis. N Engl J Med. 2025 Jul 17;393(3):255-266. doi:  10.1056/NEJMoa2503596. PMID: 40673584.

For a complete list of the evidence that informed the creation of the Gastroenteritis Bottom Line Recommendations see the Evidence Repository here.

The purpose of this document is to provide healthcare professionals with key facts and recommendations for the diagnosis and treatment of community acquired pneumonia in children in the emergency department. The TREKK Network is not liable for any damages, claims, liabilities, costs or obligations arising from the use of this document including loss or damages arising from any claims made by a third party. THIS DOCUMENT IS SUBJECT TO FULL DISCLAIMER HERE: trekk.ca/terms-of-use