Oral Prednisone or Methylprednisolone for Acute Allergic Flareups
For an adult experiencing an acute allergy flareup, administer oral prednisone 1 mg/kg daily (maximum 60-80 mg) for 2-3 days, or alternatively methylprednisolone 1 mg/kg daily (maximum 60-80 mg) if oral prednisone is not tolerated. 1, 2
Specific Dosing Regimens
Oral Corticosteroids (First-Line)
- Prednisone 1 mg/kg daily (maximum 60-80 mg) for 2-3 days is the standard recommendation for acute allergic reactions 1, 2
- For a 70 kg adult, this translates to 50-60 mg daily 1
- No tapering is required for short courses of 2-3 days 1, 2, 3
- Methylprednisolone 1 mg/kg daily (maximum 60-80 mg) serves as an equivalent alternative if oral prednisone cannot be tolerated 1, 2
Severe Urticaria-Specific Dosing
- For antihistamine-resistant chronic urticaria flares, prednisone 25 mg daily for 3 days is effective in nearly 50% of patients 4
- This lower dose (25 mg) can induce remission with effects appreciable within 24 hours of the first dose 4
- A second 3-day course may be attempted if the first course produces only temporary response, achieving remission in an additional 9% of patients 4
Acute Urticaria Without Anaphylaxis
- Prednisolone 50 mg daily for 3 days is recommended for acute urticaria in adults, though lower doses are often effective 5
- Short courses over 3-4 weeks may be necessary for urticarial vasculitis and severe delayed pressure urticaria 5
Route of Administration Hierarchy
Oral administration is preferred for stable patients with allergic flareups who can swallow without compromise 1. Intravenous methylprednisolone (40 mg IV every 6 hours, equivalent to 1-2 mg/kg/day) should be reserved for hospitalized patients or those unable to take oral medications 1, 2.
Critical Clinical Context
Role and Limitations
- Corticosteroids provide no acute benefit in allergic reactions—they serve only to prevent late-phase responses and biphasic reactions 1, 2
- The 2-3 day duration covers the window during which late-phase allergic responses might occur 1
- Corticosteroids are adjunctive therapy only and should never replace antihistamines or epinephrine (when indicated) 1, 2
When to Consider Higher Doses or Longer Duration
- Patients with history of asthma may require higher doses 1
- Severe or prolonged reactions requiring multiple interventions warrant consideration of extended courses 1
- Asthma-related allergic reactions may require prednisolone 30-60 mg daily for 1-3 weeks 2
Formulations to Avoid
Never use intramuscular corticosteroids for allergic rhinitis or routine allergic flareups—the ARIA guidelines provide a strong recommendation against this route because possible side effects may be far more serious than the condition being treated 5, 2. Dexamethasone and betamethasone are not recommended for alternate-day therapy due to prolonged HPA axis suppression 6, 3.
Complete Treatment Bundle
Every patient with an allergic flareup should receive:
- H1-antihistamine (diphenhydramine 25-50 mg or equivalent) 1
- H2-antihistamine (ranitidine or famotidine) for 2-3 days 1
- Prednisone 1 mg/kg daily for 2-3 days 1, 2
- Written instructions and follow-up plan 1
Special Situations Requiring Different Approach
Anaphylaxis
If the patient has anaphylaxis (not just an allergic flareup), epinephrine 0.3-0.5 mg IM is the only first-line treatment and must be given immediately 1, 2. Corticosteroids remain adjunctive with the same dosing (prednisone 1 mg/kg for 2-3 days at discharge) 1, 2.
Steroid Allergy
In the rare patient with documented steroid allergy (incidence 0.3% for systemic reactions), betamethasone or deflazacort may serve as alternatives, as cross-reactivity studies show these are typically tolerated when hydrocortisone and methylprednisolone cause reactions 7. However, this scenario is exceedingly uncommon and should not influence routine prescribing 8, 9.