What is the recommended dexamethasone dose for a child with croup, based on weight with the appropriate maximum limit?

Dexamethasone Dosing for Pediatric Croup

For a child with croup, administer a single dose of oral dexamethasone 0.6 mg/kg with a maximum of 16 mg, regardless of croup severity. 1, 2

Weight-Based Calculation with Maximum Limit

• Calculate the dose by multiplying 0.6 mg/kg × the child's weight in kilograms 1, 2
• Apply the maximum cap of 16 mg for any child whose calculated dose exceeds this limit 1, 2
• For example, a 38 kg child would calculate to 22.8 mg (0.6 × 38), but you would administer only the maximum of 16 mg 2

Route of Administration

• Oral administration is strongly preferred when the child can tolerate it, as it is equally effective as intramuscular or intravenous routes while avoiding injection pain 1, 2
• All three routes (oral, IM, IV) demonstrate equivalent efficacy for croup treatment 2
• The oral formulation typically comes as 4 mg/mL elixir, so a 16 mg dose equals 4 mL 2

Clinical Onset and Duration

• Symptom improvement begins as early as 30 minutes after administration, with statistically significant benefit evident by 30 minutes in mild to moderate croup 2, 3
• The clinical duration of action extends 24-72 hours, providing sustained relief from a single dose 1, 2
• This single-dose regimen does not require tapering and does not cause clinically significant adrenal suppression 2

Dose Equivalence Evidence

While the 0.6 mg/kg dose is the current standard recommendation 1, 2, research demonstrates that lower doses may be equally effective:

• A randomized trial found that 0.15 mg/kg was as effective as 0.3 mg/kg or 0.6 mg/kg in reducing hospitalization duration and croup scores 4
• Another study showed 0.15 mg/kg reduced return to medical care in mild croup compared to placebo 5
• However, the guideline-recommended dose remains 0.6 mg/kg (maximum 16 mg) based on consensus expert opinion and widespread clinical validation 1, 2

Adjunctive Therapy for Severe Cases

• For moderate to severe croup with prominent stridor, significant retractions, or respiratory distress, add nebulized epinephrine (0.5 mL/kg of 1:1000 solution, maximum 5 mL) while waiting for dexamethasone to take effect 1, 2
• Epinephrine provides immediate but short-term relief, while dexamethasone offers longer-lasting benefit 2

Important Clinical Caveats

• Do not use prednisolone as a substitute: A randomized equivalence trial showed 29% of children treated with prednisolone 1 mg/kg re-presented to medical care versus only 7% with dexamethasone 0.15 mg/kg 2, 6
• Nebulized budesonide is equally effective but less practical than oral dexamethasone in most settings 2
• Do not use inhaled corticosteroids from hand-held inhalers with spacers—they are ineffective for croup 2
• Dexamethasone provides no benefit for non-specific cough, chronic cough, or pertussis-associated cough 2

Repeat Dosing Considerations

• For severe croup with persistent symptoms, administer a repeat dexamethasone dose plus nebulized epinephrine regardless of the timing of the initial dose 2
• Most children with mild to moderate croup require only a single dose given the 24-72 hour duration of action 1, 2

Safety Profile

• Common side effects include gastric irritation, behavioral changes, weight gain, and increased appetite 1
• Exclude patients with pre-existing endocrine disorders receiving exogenous steroids or diabetes, as dexamethasone may interfere with glucose-insulin regulation 1
• One randomized trial reported higher postoperative hemorrhage rates after dexamethasone in tonsillectomy patients, though this was an unadjusted secondary outcome 1