Maximum Dose of Oral Dexamethasone for Croup
The maximum dose of oral dexamethasone for treatment of croup is 16 mg, which corresponds to 0.6 mg/kg body weight capped at this absolute maximum. 1
Recommended Dosing
Standard dose: 0.6 mg/kg (maximum 16 mg) administered as a single dose via oral, intramuscular, or intravenous route 1
The oral route is preferred when the child can tolerate it, as it is equally effective as intramuscular injection while avoiding injection pain 1
For a practical example: a child weighing 38 kg would calculate to 22.8 mg (0.6 mg/kg × 38 kg), but this must be capped at the maximum dose of 16 mg 1
Evidence Supporting Lower Doses
While 0.6 mg/kg (max 16 mg) represents the guideline-recommended dose, substantial research evidence demonstrates that lower doses may be equally effective:
Multiple randomized controlled trials have shown that 0.15 mg/kg is as effective as 0.3 mg/kg or 0.6 mg/kg in relieving croup symptoms, reducing hospitalization duration, and decreasing need for nebulized epinephrine 2, 3
A study of moderate to severe croup found no difference in croup scores between 0.15 mg/kg and 0.6 mg/kg groups at any time point, with median times to clinical improvement of 7.9 hours versus 8 hours respectively 3
The 0.15 mg/kg dose shows clinical benefit as early as 30 minutes after administration, much earlier than previously thought 4
Clinical Implications
Despite evidence supporting lower doses, the American Academy of Pediatrics guideline recommendation remains 0.6 mg/kg with a maximum of 16 mg 1. This represents the standard of care, though clinicians may consider lower doses (0.15-0.3 mg/kg) as equally effective alternatives based on research evidence 2, 3.
Adjunctive Therapy Considerations
For moderate to severe croup with significant respiratory distress, nebulized epinephrine (0.5 mL/kg of 1:1000 solution, maximum 5 mL) can be administered while waiting for dexamethasone to take effect 5, 1
The single-dose dexamethasone regimen does not require tapering and does not cause clinically significant adrenal suppression 1