Dexamethasone Dosing for Croup in a 3-Year-Old Male
Administer a single dose of dexamethasone 0.6 mg/kg (maximum 16 mg) orally, intramuscularly, or intravenously for this child with croup. 1
Dose Calculation and Administration
For a typical 3-year-old weighing approximately 14-15 kg, the calculated dose would be 8.4-9 mg of dexamethasone (0.6 mg/kg × 14-15 kg), well below the maximum of 16 mg 1
Oral administration is the preferred route when the child can tolerate it, as it is equally effective as intramuscular injection and avoids the pain of injection 1
All three routes (oral, IM, IV) are equally effective for croup treatment 1
Evidence Supporting This Dosing
The American Academy of Pediatrics recommends 0.6 mg/kg as the standard dose, with a maximum of 16 mg 1. This recommendation is supported by extensive clinical evidence, though lower doses have also been studied.
While research has shown that lower doses (0.15 mg/kg) may be equally effective, the guideline-recommended dose of 0.6 mg/kg remains the standard of care 2, 3, 4. The 0.6 mg/kg dose has the most robust evidence base and is universally accepted 5.
Onset and Duration of Action
Dexamethasone begins working as early as 30 minutes after administration, with statistically significant improvement by 30 minutes 4
The clinical duration of action is approximately 24-72 hours, providing sustained relief 1
No tapering is required with the single-dose regimen, and it does not cause significant adrenal suppression 1
Adjunctive Therapy for Moderate to Severe Cases
If the child has significant respiratory distress (stridor at rest, retractions, agitation), consider nebulized epinephrine while waiting for dexamethasone to take effect 1, 6
Nebulized epinephrine dosing: 0.5 mL/kg of 1:1000 solution (maximum 5 mL) administered by nebulizer 6
Epinephrine provides immediate but short-term symptom improvement (lasting 1-2 hours), while dexamethasone provides longer-lasting relief 1
Children requiring two epinephrine treatments should be hospitalized 7
Important Clinical Pitfalls
Do not use nebulized corticosteroids from hand-held inhalers with spacers—they are ineffective for croup 1
Nebulized budesonide is equally effective as oral dexamethasone but is less practical in most settings 1
Antihistamines, decongestants, and antibiotics have no proven effect on uncomplicated viral croup 7