Hydrocortisone 100mg for Acute Asthma
Hydrocortisone 100mg IV is inadequate for acute severe asthma—use 200mg IV every 6 hours instead, or give oral prednisolone 30-60mg as an equally effective alternative.
Recommended Dosing
The British Thoracic Society guidelines explicitly recommend hydrocortisone 200mg IV (not 100mg) as the standard dose for acute severe asthma, administered immediately upon presentation. 1 This higher dose should be continued every 6 hours in patients who are seriously ill or vomiting. 1
Dosing Algorithm:
- Initial dose: Hydrocortisone 200mg IV OR prednisolone 30-60mg orally (or both if patient is very ill) 1, 2
- Continuation: Hydrocortisone 200mg IV every 6 hours for seriously ill or vomiting patients 1
- Alternative: Prednisolone 30-60mg daily orally if patient can tolerate oral medication 1
Evidence on Lower Doses
While research suggests that lower doses may be effective, this contradicts guideline recommendations. A randomized trial found hydrocortisone 50mg IV four times daily (200mg total/24 hours) was as effective as 500mg doses 3, and another study showed 100mg IV every 6 hours (400mg total/24 hours) had similar efficacy to higher doses 4, 5. A Cochrane review concluded that low-dose corticosteroids (≤400mg/day hydrocortisone) appear adequate. 6
However, these research findings used total daily doses of 200-400mg, not a single 100mg dose. The question of a single 100mg dose is not supported by any evidence.
Critical Dosing Distinction
The 100mg dose mentioned in your question falls short of guideline recommendations in two ways:
- Single dose inadequacy: One 100mg dose provides insufficient steroid coverage 1
- Frequency matters: Even if using lower doses, they must be repeated (e.g., 100mg every 6 hours = 400mg/24 hours) 4, 5
Route of Administration
Oral prednisolone is equally effective as IV hydrocortisone and should be preferred in patients who can swallow. 4, 5 Reserve IV hydrocortisone for patients who are:
Common Pitfall
The most critical error is underdosing systemic corticosteroids in acute severe asthma, which can be fatal. 1 A single 100mg dose of hydrocortisone does not meet the evidence-based standard of care. If using hydrocortisone IV, the dose must be 200mg initially and repeated every 6 hours. 1
Comparative Efficacy
One study found hydrocortisone 200mg every 4 hours superior to methylprednisolone 125mg every 12 hours in reducing asthma unit stay duration (30 vs 36 hours, P=0.01). 7 This supports using adequate hydrocortisone dosing when the IV route is selected.