Dexamethasone Dosing for Croup in a 5-Year-Old Weighing 41 Pounds
Administer dexamethasone 0.6 mg/kg as a single dose, which equals 11.2 mg for this 41-pound (18.6 kg) child, given orally, intramuscularly, or intravenously (maximum dose 16 mg). 1
Dose Calculation
- Weight conversion: 41 pounds = 18.6 kg
- Standard dose: 0.6 mg/kg × 18.6 kg = 11.2 mg 1
- This is well below the maximum dose of 16 mg 1
Route of Administration
Oral administration is preferred when the child can tolerate it, as it is equally effective as intramuscular or intravenous routes and avoids the pain of injection. 1 All three routes (oral, IM, IV) demonstrate equivalent efficacy for croup treatment. 1
Onset and Duration of Action
- Onset: Symptom improvement begins as early as 30 minutes after administration, though full effect typically occurs around 6 hours 1, 2
- Duration: Clinical effects last approximately 24-72 hours 1
- No tapering required: The single-dose regimen does not cause significant adrenal suppression and does not require tapering 1
Adjunctive Therapy Considerations
For moderate to severe croup with significant respiratory distress (prominent stridor, significant retractions, agitation):
- Consider nebulized epinephrine while waiting for dexamethasone to take effect 1, 3
- Epinephrine dose: 0.5 mL/kg of 1:1000 solution (maximum 5 mL) by nebulizer 3
- Epinephrine provides immediate but short-term relief, while dexamethasone provides longer-lasting benefit 1
Evidence Supporting Lower Doses
While 0.6 mg/kg is the standard recommended dose, research demonstrates that 0.15 mg/kg may have similar efficacy in moderate to severe croup. 4, 5 A randomized trial found no difference in croup scores between 0.15 mg/kg and 0.6 mg/kg doses. 5 However, the American Academy of Pediatrics continues to recommend 0.6 mg/kg as the standard dose, and this should be used unless there are specific contraindications. 1
Common Pitfalls to Avoid
- Do not use lower doses (e.g., 0.15 mg/kg) as first-line therapy unless following specific institutional protocols, as the standard 0.6 mg/kg dose is universally recommended 1, 2
- Do not use nebulized corticosteroids from hand-held inhalers with spacers—they are ineffective for croup 1
- Monitor for at least 2 hours after epinephrine administration if used, due to risk of rebound airway obstruction 2
- Do not assume repeat dosing is necessary—the single dose typically provides 24-72 hours of relief 1
Repeat Dosing Indications
Administer a repeat dexamethasone dose plus nebulized epinephrine only for severe croup with prominent stridor, significant retractions, and agitation, regardless of timing of the initial dose. 1