A 15-month-old child with croup receiving 2 mg dexamethasone: what is the equivalent prednisolone dose?

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Last updated: October 20, 2026 • View editorial policy

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Prednisolone Equivalent for 2 mg Dexamethasone in Croup

For a 15-month-old child with croup receiving 2 mg of dexamethasone, the equivalent prednisolone dose is approximately 13-15 mg.

Corticosteroid Equivalency Calculation

The conversion between dexamethasone and prednisolone is based on their relative anti-inflammatory potencies:

  • Dexamethasone is approximately 6.7 times more potent than prednisolone 1, 2
  • 2 mg dexamethasone × 6.7 = 13.4 mg prednisolone

According to FDA labeling, 2.25 mg dexamethasone equals 15 mg prednisolone, which aligns closely with this calculation 1.

Clinical Context for Croup Treatment

Standard Dosing in Croup

For croup management, the typical doses are:

  • Dexamethasone: 0.15-0.6 mg/kg (most commonly 0.15 mg/kg) 3, 4
  • Prednisolone: 1 mg/kg 4, 5, 6

Weight-Based Calculation for This Patient

For a 15-month-old child:

  • If the child weighs approximately 10-11 kg (typical for this age)
  • 2 mg dexamethasone represents roughly 0.18-0.2 mg/kg
  • The equivalent prednisolone dose would be 1 mg/kg = 10-11 mg

Important Clinical Considerations

The direct mathematical conversion (13-15 mg) differs from the weight-based clinical dosing (10-11 mg) because croup treatment protocols use standardized mg/kg dosing rather than strict pharmacologic equivalency.

Evidence on Comparative Effectiveness

Recent high-quality evidence demonstrates that prednisolone 1 mg/kg is NOT equivalent to dexamethasone 0.15 mg/kg for croup 6. Children treated with prednisolone had significantly higher re-presentation rates (29% vs 7%, with confidence intervals outside the equivalence range). However, a larger 2019 trial found prednisolone 1 mg/kg to be non-inferior to dexamethasone 0.6 mg/kg 4.

Practical Recommendation

If substituting prednisolone for dexamethasone in croup:

  • Use 1 mg/kg prednisolone (the evidence-based dose for croup) rather than attempting strict pharmacologic conversion
  • For a 10-11 kg child, this equals 10-11 mg prednisolone
  • Be aware that prednisolone may result in higher re-presentation rates compared to dexamethasone 6

Dexamethasone remains the preferred corticosteroid for croup due to superior efficacy in reducing unscheduled medical re-attendance 6, 3.

References

3
Research

Glucocorticoids for croup in children.

The Cochrane database of systematic reviews, 2023

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.