Recommended IM Dexamethasone Dosage for Pediatric Croup
Administer a single intramuscular dose of dexamethasone 0.6 mg/kg (maximum 16 mg) for pediatric croup. 1
Standard Dosing Protocol
- The recommended dose is 0.6 mg/kg with a maximum of 16 mg, which can be given via oral, intramuscular, or intravenous routes with equal efficacy 1
- For intramuscular administration specifically, the 0.6 mg/kg dose has been the standard recommendation supported by the American Academy of Pediatrics 1
- This single dose provides clinical benefit lasting 24-72 hours, with onset of action as early as 30 minutes 1
Lower Dose Alternative
- Dexamethasone 0.15 mg/kg (maximum 3 mg) is probably equally effective as the standard 0.6 mg/kg dose for moderate to severe croup 2
- High-certainty evidence shows no difference in croup scores at 2 hours between 0.15 mg/kg and 0.6 mg/kg doses 3
- There is no difference in return visits, readmissions, or need for additional treatments (including epinephrine or intubation) between these doses 3
- The lower dose may be considered to minimize potential adverse effects while maintaining efficacy 2
Route of Administration Considerations
- All three routes (oral, IM, IV) are equally effective for croup treatment 1
- Oral administration is preferred when the child can tolerate it, as it avoids injection pain while providing equivalent efficacy 1
- Intramuscular administration is appropriate when oral intake is not feasible due to respiratory distress or vomiting 4
Adjunctive Therapy
- For moderate to severe croup with significant respiratory distress, consider nebulized racemic epinephrine (0.5 mL of 2.25% solution diluted in 2.5 mL saline) while waiting for dexamethasone to take effect 4
- Epinephrine provides immediate but short-term relief, while dexamethasone offers longer-lasting benefit 1
- Children requiring two epinephrine treatments should be hospitalized 4
Important Clinical Caveats
- The single-dose regimen does not require tapering and does not cause significant adrenal suppression 1
- Do not use nebulized corticosteroids from hand-held inhalers with spacers—they are ineffective for croup 1
- Nebulized budesonide (4 mg) is equally effective as dexamethasone but oral/IM dexamethasone is simpler and more practical in most settings 5
Historical Context and Evidence Strength
- Despite strong evidence, steroids were historically underutilized even in severe croup, with only 16% of severe cases receiving steroids in one 1984 series 6
- Current high-certainty evidence from Cochrane reviews confirms glucocorticoids reduce symptoms at 2 hours, shorten hospital stays, and reduce return visits 3
- The recommendation for at least 1.0-1.5 mg/kg dexamethasone for patients requiring racemic epinephrine has been supported since the 1980s 6