Dexamethasone Dosing for Croup
For children aged 6 months to 5 years with croup, administer a single dose of dexamethasone 0.6 mg/kg (maximum 16 mg) via the oral route when the child can tolerate it. 1, 2, 3
Dosing Recommendations
- Standard dose: 0.6 mg/kg (maximum 16 mg) administered as a single dose 1, 2, 3
- Lower dose alternative: 0.15 mg/kg is equally effective and may reduce side effects, particularly for mild to moderate croup 2, 4, 5
- For a typical 2-year-old weighing 12-13 kg, the standard dose translates to approximately 7-8 mg 3
Evidence Supporting Lower Dosing
The evidence for lower-dose dexamethasone is compelling. Multiple randomized controlled trials demonstrate that 0.15 mg/kg achieves comparable clinical improvement to 0.6 mg/kg in both mild-to-moderate 4, 6 and moderate-to-severe croup 5. However, the American Academy of Pediatrics continues to recommend 0.6 mg/kg as the standard dose 1, 2, 3, likely reflecting conservative practice and the established safety profile at this dose.
Route of Administration
- Oral administration is preferred when the child can tolerate it—equally effective as intramuscular or intravenous routes while avoiding injection pain 1, 2, 3
- All three routes (oral, IM, IV) demonstrate equivalent efficacy 1, 3
- Intramuscular or intravenous routes should be reserved for children who cannot tolerate oral medication due to vomiting or severe distress 1, 2
Critical Caveat on Nebulized Corticosteroids
Do not use nebulized corticosteroids from hand-held inhalers with spacers—they are ineffective for croup 1, 2. While nebulized budesonide is equally effective as oral dexamethasone, oral administration is simpler and more practical in most settings 1.
Onset and Duration of Action
- Onset: as early as 30 minutes after administration, with statistically significant benefit evident by 30 minutes 2, 3, 6
- Duration: 24-72 hours of sustained symptom relief 1, 2, 3
- No tapering required—the single-dose regimen does not cause significant adrenal suppression 1, 2
This rapid onset is clinically important and contradicts older teaching that suggested waiting 4-6 hours for benefit 6.
Management of Moderate to Severe Croup
For children with marked respiratory distress, prominent stridor, significant retractions, or agitation:
- Administer nebulized epinephrine (0.5 mL/kg of 1:1000 solution, maximum 5 mL) while awaiting dexamethasone's onset 1, 2, 3
- Epinephrine provides immediate but short-term relief (lasting approximately 2 hours), while dexamethasone provides longer-lasting benefit 1, 3
- For severe croup with persistent symptoms, administer a repeat dexamethasone dose plus nebulized epinephrine regardless of the timing of the initial dose 1, 2
- Children requiring two epinephrine treatments should be hospitalized 7
Important Clinical Caveats
- Dexamethasone should NOT be used for non-specific cough, chronic cough, or pertussis-associated cough—it provides no benefit in these conditions 1, 2
- Dexamethasone is specifically indicated for croup (laryngotracheobronchitis), characterized by the classic "seal-like barking cough" 3
- Prednisolone is less effective than dexamethasone, with a 29% re-presentation rate compared to 7% with dexamethasone 1, 2
Common Pitfall
Do not confuse croup with other causes of cough or upper airway symptoms. The characteristic barking cough, inspiratory stridor, and hoarseness distinguish croup from bronchiolitis, asthma, or simple upper respiratory infections where dexamethasone has no role 1, 2, 3.