Dexamethasone for Croup: Single Dose Administration
Dexamethasone for croup is given as a single dose only, not repeated doses. The standard approach is one dose of 0.6 mg/kg (maximum 10-12 mg) orally or intramuscularly, which provides therapeutic benefit for the entire course of the illness 1, 2.
Evidence for Single-Dose Efficacy
A single dose of dexamethasone 0.6 mg/kg has been proven effective for moderate-to-severe croup, reducing hospitalizations, length of illness, and need for subsequent treatments compared to placebo 1.
The pharmacokinetic profile supports single dosing: dexamethasone has a biological half-life of 36-72 hours, making it a long-acting corticosteroid that provides sustained anti-inflammatory effects throughout the typical croup illness duration 3.
Clinical trials consistently used single-dose protocols: A randomized controlled trial of 72 hospitalized children demonstrated that one intramuscular dose of 0.6 mg/kg dexamethasone significantly shortened hospital stay and improved clinical outcomes at 6 and 12 hours post-administration 4.
Outpatient management also relies on single dosing: A study of 277 children with moderate croup showed that a single dose (either oral or intramuscular) was effective, with only 8% requiring any additional intervention 2.
Dosing Options Based on Severity
For moderate-to-severe croup:
- Standard dose: 0.6 mg/kg (maximum 10-12 mg) orally or intramuscularly 1, 2
- Route selection: Oral is preferred for ease of administration; intramuscular is reserved for vomiting or severe respiratory distress 1
For mild croup:
- Lower dose option: 0.15 mg/kg may be sufficient 1, 5
- A double-blind trial of 100 children demonstrated that even 0.15 mg/kg as a single oral dose effectively reduced return to medical care for ongoing croup 5
- Another study confirmed that 0.15 mg/kg and 0.6 mg/kg were equally effective for moderate-to-severe croup 6
When Additional Doses Are NOT Indicated
Repeat dosing is not part of standard croup management because the single dose provides coverage for the typical 3-5 day illness course 1.
If symptoms persist or worsen after the initial dose, this suggests either treatment failure requiring escalation (such as nebulized epinephrine or hospitalization) or an alternative diagnosis—not a need for more dexamethasone 1, 2.
Only 8% of children required any subsequent intervention (additional steroids, racemic epinephrine, or admission) after a single dose in outpatient studies 2.
Critical Caveat
If a child returns with ongoing croup symptoms after receiving dexamethasone, consider: