Anaphylaxis Steroid Regimen
Corticosteroids should be administered as adjunctive therapy during anaphylaxis treatment at a dose of methylprednisolone 1-2 mg/kg IV every 6 hours (typically 40 mg IV every 6 hours for adults) or hydrocortisone 100 mg IV, continued for 2-3 days to potentially prevent biphasic or protracted reactions—though they provide no acute benefit and should never delay or replace epinephrine administration. 1
Critical Context: Corticosteroids Are NOT First-Line Treatment
- Epinephrine 0.3-0.5 mg IM (1:1000 dilution) into the anterolateral thigh remains the only first-line treatment for anaphylaxis and must be given immediately. 1
- Corticosteroids have a slow onset of action (4-6 hours) and do not treat acute anaphylactic symptoms. 2
- The primary rationale for corticosteroid use is prevention of biphasic reactions (which occur in up to 20% of cases) and protracted anaphylaxis, not acute symptom management. 2
Recommended Steroid Regimens
Adult Dosing
- Methylprednisolone: 1-2 mg/kg IV every 6 hours (typically 40 mg IV every 6 hours for a 70 kg adult), continued for 2-3 days. 1
- Hydrocortisone: 100 mg IV as an alternative formulation. 1
- Prednisone (for discharge): 1 mg/kg daily (maximum 60-80 mg) orally for 2-3 days. 1
Pediatric Dosing
- Methylprednisolone: 1-2 mg/kg/day IV divided every 6 hours for hospitalized children. 1
- Prednisone: 0.5 mg/kg orally for less severe episodes being discharged. 1
- Hydrocortisone: Age-based dosing—100 mg IM/IV for ages 6-12 years, 50 mg IM/IV for ages 6 months to 6 years, 25 mg IM/IV for under 6 months. 1
Duration and Tapering
- Treatment duration: 2-3 days only, as all reported biphasic reactions have occurred within 3 days. 2
- No tapering required: Short courses of 2-3 days do not require a taper. 1
- Extending treatment beyond 3 days is unnecessary and should be avoided. 1
Evidence Quality and Limitations
- No high-quality evidence exists: A Cochrane systematic review found zero randomized controlled trials supporting or refuting corticosteroid use in anaphylaxis. 3
- Observational data is mixed: Corticosteroids may reduce hospital length of stay but do not consistently prevent biphasic reactions or reduce ED revisits. 4
- Recent registry data raises concerns: A 2023 study of 5,364 anaphylaxis cases found that prehospital corticosteroid use was associated with increased need for IV fluids (aOR 1.059) and hospital admission (aOR 1.232), suggesting potential harm or confounding by severity. 5
- Current practice is empiric: Despite weak evidence, corticosteroid use remains prevalent (68% of cases) and is supported by expert consensus based on theoretical benefits. 4
When to Prioritize Corticosteroids
Consider corticosteroids particularly for patients with: 1
- History of asthma
- Severe or prolonged anaphylaxis requiring multiple epinephrine doses
- History of idiopathic anaphylaxis
- Significant generalized urticaria or angioedema
Critical Pitfalls to Avoid
- Never delay epinephrine while administering corticosteroids—this increases mortality risk. 6
- Never substitute corticosteroids for epinephrine—they do not treat acute symptoms (stridor, bronchospasm, hypotension, or shock). 2
- Do not prescribe corticosteroids alone at discharge—patients must receive epinephrine auto-injectors as the primary intervention. 1
- Avoid premature discharge—observe patients for at least 4-6 hours after symptom resolution, longer for severe reactions or those requiring multiple epinephrine doses. 1
Complete Adjunctive Medication Regimen
Beyond corticosteroids, the full adjunctive regimen includes: 1
- H1-antihistamine: Diphenhydramine 25-50 mg IV/IM (1-2 mg/kg)
- H2-antihistamine: Ranitidine 50 mg IV or famotidine 20 mg IV (combination H1+H2 superior to H1 alone)
- Beta-agonist: Albuterol nebulization 2.5-5 mg for persistent bronchospasm unresponsive to epinephrine