What systemic corticosteroid regimen is recommended for an otherwise healthy adult with a moderate acute allergic reaction (widespread urticaria and angio‑edema without airway compromise)?

Systemic Corticosteroid Regimen for Moderate Acute Allergic Reaction

For an otherwise healthy adult with widespread urticaria and angioedema without airway compromise, prescribe prednisone 50 mg orally daily for 3 days. 1

Treatment Algorithm

First-Line Treatment: Antihistamines

• Start with H1 antihistamines (cetirizine 10 mg or loratadine 10 mg daily) as the primary treatment for moderate urticaria and angioedema without airway involvement. 1
• Add H2 antihistamines (ranitidine 50 mg twice daily) for superior symptom control when combined with H1 antagonists. 2
• Monitor closely for 30-60 minutes to ensure no progression to more severe symptoms requiring epinephrine. 1

When to Add Corticosteroids

Corticosteroids are indicated when:

• Urticaria is severe (covering >30% body surface area) 3
• Symptoms fail to respond adequately to antihistamines alone 1
• There is significant angioedema requiring additional anti-inflammatory therapy 1

Specific Corticosteroid Regimen

Prednisone 50 mg orally daily for 3 days is the guideline-recommended regimen for adults with acute urticaria. 1

Alternative considerations:

• Lower doses (20-40 mg daily) are frequently effective and should be considered to minimize corticosteroid exposure. 1, 3
• Methylprednisolone 1 mg/kg daily (maximum 60-80 mg) can be used as an alternative if oral prednisone is not tolerated. 2
• Do not taper for short 3-day courses—tapering is unnecessary. 2

Role and Limitations of Corticosteroids

• Corticosteroids provide no acute benefit in allergic reactions; they work to prevent biphasic or protracted reactions over 6-24 hours. 1, 2
• Little data support their use for preventing biphasic reactions, but they are commonly recommended due to anti-inflammatory properties. 1
• Never use corticosteroids as monotherapy—antihistamines remain the foundation of treatment. 3, 4

Complete Discharge Bundle

When discharging the patient, provide:

• Prednisone 50 mg daily for 3 days (or 20-40 mg if milder presentation) 1, 3
• H1 antihistamine (diphenhydramine 25-50 mg every 6 hours OR non-sedating second-generation antihistamine) for 2-3 days 1
• H2 antihistamine (ranitidine 150 mg twice daily) for 2-3 days 1
• Epinephrine auto-injector (two doses) with hands-on training if there is any concern for progression or history of severe reactions 1, 2
• Written anaphylaxis action plan 2

Critical Pitfalls to Avoid

Never Delay Epinephrine if Symptoms Progress

• If progression to respiratory symptoms, hypotension, or severe angioedema occurs, administer epinephrine 0.3-0.5 mg IM immediately. 2
• Antihistamines and corticosteroids are never substitutes for epinephrine in anaphylaxis. 1, 2

Never Use Long-Term Corticosteroids

• Long-term oral corticosteroids should not be used for chronic urticaria (>6 weeks duration) except in very selected cases under specialist supervision. 1, 4
• Maximum duration is 3-10 days for acute exacerbations to avoid cumulative toxicity. 4

Observation Period

• Observe for 4-6 hours after symptom resolution to monitor for biphasic reactions, which occur in 7-18% of cases. 2
• Extend observation if there is a history of severe reactions, asthma, or requirement for multiple medication doses. 2

Special Considerations

When Antihistamines Alone Are Sufficient

• Mild urticaria (flushing, isolated mild angioedema without respiratory symptoms) can be treated with H1 and H2 antihistamines alone. 1
• Corticosteroids are not first-line when antihistamines provide adequate control. 4

Escalation for Refractory Cases

• If symptoms persist beyond 6 weeks (chronic urticaria) despite antihistamines and short corticosteroid courses, increase antihistamine dose up to 4 times standard dose (e.g., cetirizine 40 mg daily) before considering other immunomodulators. 3, 4
• Omalizumab 300 mg subcutaneously every 4 weeks is the next step for antihistamine-refractory chronic urticaria, not chronic corticosteroids. 3, 4