What is the maximum single dose of dexamethasone (corticosteroid) in milligrams (mg) for a 5-year-old child with croup?

Maximum Dexamethasone Single Dose for Croup in a 5-Year-Old Child

The maximum single dose of dexamethasone for croup in a 5-year-old child is 0.6 mg/kg with a maximum dose of 12 mg.

Dosing Recommendations

Dexamethasone is the cornerstone of croup management in children, with substantial evidence supporting its efficacy. The dosing recommendations are as follows:

• Standard recommended dose: 0.6 mg/kg (maximum 12 mg) as a single dose 1
• Lower effective dose: 0.15 mg/kg has also been shown to be effective in many cases 2, 3

Evidence for Dosing

Research evidence supports several key points regarding dexamethasone dosing for croup:

• A randomized comparison study demonstrated that both 0.15 mg/kg and 0.6 mg/kg doses were equally effective in treating moderate to severe croup, with no significant differences in croup score reduction between the two dosages 1

• A Cochrane systematic review (2023) found that while 0.6 mg/kg dexamethasone probably reduced croup severity at 24 hours compared to 0.15 mg/kg, there was little to no difference at 2 hours and 6 hours between the doses 3

• For children with mild to moderate croup, a dose of 0.15 mg/kg has been shown to provide benefit as early as 30 minutes after administration 4

Administration Considerations

• Route of administration: Dexamethasone can be given orally, intramuscularly, or intravenously
• Timing: A single dose is typically sufficient for most cases of croup
• Onset of action: Benefits may begin as early as 30 minutes after administration, contrary to previous beliefs that benefits take 4-6 hours to appear 4

Clinical Decision-Making Algorithm

1. Assess croup severity:

   • Mild: Barky cough, no stridor at rest
   • Moderate: Barky cough, stridor at rest, mild retractions
   • Severe: Barky cough, prominent stridor, marked retractions, agitation/lethargy

2. Determine appropriate dose:

   • For mild to moderate croup: 0.15-0.6 mg/kg (lower dose may be sufficient)
   • For severe croup: 0.6 mg/kg (maximum 12 mg)

3. Calculate the actual dose:

   • For a 5-year-old child (approximately 18-20 kg):
     • At 0.6 mg/kg: 10.8-12 mg (maximum dose would be 12 mg)
     • At 0.15 mg/kg: 2.7-3 mg

Important Clinical Considerations

• While lower doses (0.15 mg/kg) may be effective for many children with croup, the maximum recommended single dose remains 0.6 mg/kg with a ceiling of 12 mg 1

• Children with severe croup (stridor at rest with marked respiratory distress) may require additional treatments such as nebulized epinephrine along with dexamethasone 5

• A single dose of dexamethasone is typically sufficient for most cases of croup, with return visits or readmissions significantly reduced compared to placebo 3

Common Pitfalls to Avoid

• Underdosing in severe cases: While 0.15 mg/kg may be effective for mild-moderate croup, severe cases may benefit from the full 0.6 mg/kg dose

• Unnecessary repeat dosing: A single dose is usually sufficient; routine multiple doses are generally not needed

• Delayed administration: Early administration of dexamethasone is key to preventing progression of symptoms and reducing the need for additional interventions

• Confusing with other steroid dosing: Dexamethasone dosing for croup differs from dosing for other conditions like asthma or bacterial meningitis