What is the appropriate dexamethasone dose for a 70‑lb (≈32‑kg) child with croup?

Dexamethasone Dosing for Croup in a 70-Pound Child

For a 70-pound (approximately 32 kg) child with croup, administer a single dose of 4.8 mg of oral dexamethasone (0.15 mg/kg). 1

Recommended Dosing

• The standard dose is 0.15 mg/kg given as a single oral dose, which for a 32 kg child equals 4.8 mg 1, 2
• This dose can be rounded to 5 mg for practical administration 2
• The medication works rapidly, with clinical benefit evident by 30 minutes and statistically significant improvement by this timepoint 3

Evidence Supporting Lower-Dose Dexamethasone

Multiple high-quality randomized controlled trials demonstrate that 0.15 mg/kg is equally effective as higher doses:

• A randomized trial of 120 hospitalized children showed no difference in hospitalization duration, croup score reduction, or need for nebulized epinephrine between 0.15 mg/kg, 0.3 mg/kg, and 0.6 mg/kg doses 2
• A separate randomized trial of 41 children with moderate to severe croup found 0.15 mg/kg and 0.6 mg/kg equally effective, with median time to clinical improvement of approximately 8 hours in both groups 4
• A 2023 randomized controlled trial of 226 children confirmed that 0.15 mg/kg oral dexamethasone significantly reduced Westley Croup Scores at 4 hours 5

Route of Administration

• Oral administration is preferred when the child can tolerate it 6
• Oral and IV dexamethasone have 1:1 dose equivalence, so 4.8 mg PO = 4.8 mg IV 7
• Reserve intramuscular administration for children who are vomiting or in severe respiratory distress unable to tolerate oral medication 6

Clinical Advantages of the 0.15 mg/kg Dose

• Lower risk of adverse effects while maintaining equivalent efficacy 2, 4
• Encourages treatment of all severities of croup without concern for steroid-related complications 3
• Corticosteroid-induced complications in croup are rare at this dosing 6

Severe Croup Considerations

• For severe cases, dexamethasone may be combined with nebulized epinephrine (0.5 mL/kg of 1:1000 solution, maximum 5 mL) for more rapid symptom relief 1
• The dexamethasone dose remains 0.15 mg/kg even when combined with epinephrine 4

Common Pitfall to Avoid

• Do not use the outdated 0.6 mg/kg dose (which would be 19.2 mg for this child), as it provides no additional benefit over 0.15 mg/kg and unnecessarily increases steroid exposure 2, 4
• The historical recommendation of 0.6 mg/kg has been superseded by evidence showing lower doses are equally effective 6