Treatment of Acute Urticaria
Start with a second-generation non-sedating H1 antihistamine at standard dose, and if symptoms persist after 2-3 days, add a short 3-day course of oral corticosteroids (prednisolone 50 mg daily), which achieves complete remission in 94% of patients within 3 days compared to 66% with antihistamines alone. 1
First-Line Treatment: Second-Generation Antihistamines
Begin immediately with a second-generation non-sedating H1 antihistamine as the cornerstone of acute urticaria management. 2, 3 Options include:
Offer patients at least two different antihistamine options, as individual responses and tolerance vary significantly between agents. 2, 3 This is particularly important in acute urticaria where rapid symptom control is the priority.
Avoid first-generation antihistamines (diphenhydramine, hydroxyzine, chlorpheniramine) as primary therapy due to significant sedation and potential to worsen outcomes in severe reactions. 2 While older literature supported their use, current evidence demonstrates second-generation agents are equally effective without the adverse cognitive and sedative effects. 4, 5
Dose Escalation Strategy
If standard dosing provides inadequate control within 24-48 hours, increase the antihistamine dose up to 4 times the standard dose when benefits outweigh risks. 2, 3 This updosing approach is well-established for chronic urticaria and can be applied to severe acute cases. 6
Corticosteroid Use
For moderate to severe acute urticaria, add a short course of oral corticosteroids rather than waiting for antihistamine failure. 6, 7 The evidence strongly supports this approach:
- Prednisolone 50 mg daily for 3 days achieves complete remission in 93.8% of patients, compared to only 65.9% with antihistamines alone (p < 0.001). 1
- Restrict corticosteroids to short 3-10 day courses only—never use chronically due to cumulative dose- and time-dependent toxicity. 5
- This is particularly indicated for severe acute urticaria or angioedema affecting the mouth or airway. 6, 7
Emergency Management
For acute urticaria with signs of anaphylaxis (respiratory distress, hypotension, throat swelling), immediately administer intramuscular epinephrine 0.5 mL of 1:1000 solution (500 µg) into the anterolateral thigh. 2, 7 Epinephrine alleviates pruritus, urticaria, and angioedema through its effects on vascular permeability and smooth muscle relaxation. 8
After epinephrine, add antihistamines and corticosteroids as adjunctive therapy. 2 The epinephrine addresses the immediate life-threatening component while other agents provide sustained symptom control.
Adjunctive Measures
Identify and eliminate triggering factors immediately:
- Upper respiratory tract infections are the most common association (39.5% of cases). 1
- Analgesics and NSAIDs account for 9.2% of drug-induced cases. 1
- Avoid aspirin, NSAIDs, and codeine in all patients until triggers are clarified. 3, 7
- Minimize overheating, stress, and alcohol consumption. 3, 7
Apply cooling antipruritic lotions (calamine or 1% menthol in aqueous cream) for symptomatic relief while waiting for pharmacotherapy to take effect. 3, 7
Clinical Course and Prognosis
Acute urticaria is self-limited in all cases, with the longest episodes lasting 3 weeks. 1 Most patients experience moderate (42%) to severe (40%) disease initially, but symptoms resolve completely with appropriate treatment. 1
The condition is frequently idiopathic (>50% of cases) and only rarely associated with IgE-mediated allergic events, so extensive allergy testing is not warranted in the acute setting. 1 Focus on symptom control rather than exhaustive investigation.
Common Pitfalls to Avoid
Do not use H2 antihistamines or leukotriene antagonists in acute urticaria—the literature does not support significant efficacy for these agents in the acute setting, though they may have limited roles in chronic disease. 5
Do not prescribe first-generation antihistamines at night despite historical practice—studies show they alter REM sleep patterns and learning curves without superior efficacy compared to non-sedating agents. 4
Do not delay corticosteroids in moderate-to-severe cases—the evidence clearly demonstrates faster resolution with early corticosteroid addition rather than sequential escalation. 1