What is the recommended dexamethasone (Decameron) dose for a child with croup, including route, maximum dose, and repeat‑dosing guidelines?

Dexamethasone Dosing for Croup

For children with croup, administer dexamethasone 0.15 mg/kg as a single dose (maximum 10 mg), given orally or intramuscularly—both routes are equally effective. 1, 2, 3, 4

Recommended Dose and Route

• Standard dose: 0.15 mg/kg as a single dose (maximum dose typically 8–10 mg) 1, 2, 5, 3
• Route of administration: Oral and intramuscular routes are equally effective; choose based on clinical context and patient cooperation 4
• Oral administration is preferred when the child can tolerate it, as it avoids injection pain and achieves equivalent outcomes 4
• Intramuscular administration is appropriate when oral intake is not feasible due to vomiting, severe distress, or inability to swallow 4

Evidence Supporting Lower Dose (0.15 mg/kg vs. 0.6 mg/kg)

Multiple high-quality randomized controlled trials demonstrate that 0.15 mg/kg dexamethasone is as effective as the traditional 0.6 mg/kg dose for all severities of croup:

• Hospitalization duration is identical between 0.15 mg/kg and 0.6 mg/kg doses (median 9 hours for both) 1
• Croup score reduction at 2,6,12, and 24 hours shows no significant difference between doses 1, 2, 3
• Need for additional treatments (nebulized epinephrine, supplemental steroids, intubation) does not differ between doses 2, 3
• Return visits and readmissions occur at similar rates regardless of dose (0.15 mg/kg vs. 0.6 mg/kg: RR 0.91,95% CI 0.71–1.17) 3
• The 2023 Cochrane systematic review (45 RCTs, 5888 children) concludes that 0.15 mg/kg may be as effective as 0.60 mg/kg 3

Time to Onset of Action

• Clinical benefit begins at 30 minutes after oral administration of 0.15 mg/kg dexamethasone 5
• This is much earlier than the 4–6 hours previously suggested by older guidelines 5
• Croup score reduction is statistically significant by 30 minutes and continues to improve through 12 hours 5

Maximum Dose Considerations

• Practical maximum: 8–10 mg per dose 1, 4
• For a 0.15 mg/kg dose, this maximum is reached at approximately 53–67 kg body weight 1
• Higher doses (0.6 mg/kg) offer no additional clinical benefit but increase steroid exposure unnecessarily 1, 2, 3

Repeat Dosing Guidelines

• A single dose is typically sufficient for most children with croup 1, 2, 4
• No routine repeat dosing is recommended within the first 24 hours 1, 4
• If symptoms persist or worsen after initial treatment:
  • Reassess for complications (bacterial tracheitis, epiglottitis, foreign body) 4
  • Consider additional treatments such as nebulized epinephrine for severe respiratory distress 2, 4
  • A second dose of dexamethasone may be given if the child returns with recurrent symptoms after 24 hours, but this is uncommon (occurs in ~8% of cases) 4

No Tapering Required

• Short-course dexamethasone for croup does not require tapering 6
• A single dose or 2–4 day course does not cause clinically significant adrenal suppression 6
• This is in contrast to prolonged high-dose steroid therapy, which may require tapering 7

Common Pitfalls to Avoid

• Do not routinely use 0.6 mg/kg dosing: The evidence strongly supports 0.15 mg/kg as equally effective with lower steroid exposure 1, 2, 3
• Do not delay treatment waiting for 4–6 hours of benefit: Dexamethasone works within 30 minutes 5
• Do not assume intramuscular is superior to oral: Both routes are equally effective; choose based on patient factors 4
• Do not prescribe tapering regimens: A single dose or short course (2–4 days) does not require tapering 6
• Do not confuse croup dosing with other indications: Bacterial meningitis requires 0.15 mg/kg every 6 hours for 2–4 days, which is a different regimen 8, 7

Safety and Adverse Effects

• Adverse events are rare with single-dose dexamethasone for croup 2, 3
• No significant adverse reactions were reported in trials comparing 0.15 mg/kg to 0.6 mg/kg 2
• Lower doses (0.15 mg/kg) minimize potential steroid-related side effects (hyperglycemia, hypertension, behavioral changes) while maintaining efficacy 2, 3

Clinical Algorithm

1. Confirm diagnosis of croup (barking cough, inspiratory stridor, hoarseness)
2. Assess severity using croup score (mild, moderate, or severe)
3. Administer dexamethasone 0.15 mg/kg (maximum 8–10 mg) as a single dose 1, 2, 3
4. Choose route: Oral if tolerated; intramuscular if oral not feasible 4
5. Expect improvement within 30 minutes 5
6. Discharge home if mild to moderate croup with appropriate follow-up instructions 4
7. Observe for 2–4 hours if severe croup or if nebulized epinephrine was required 2, 4
8. No repeat dose needed unless symptoms recur after 24 hours 4