Treatment of Acute Hives on Extremities
Start immediately with a standard dose of a second-generation non-sedating H1 antihistamine such as cetirizine, fexofenadine, or loratadine, as this is the definitive first-line treatment for acute urticaria. 1, 2, 3, 4
Immediate First-Line Management
Administer a second-generation antihistamine immediately – options include cetirizine (10 mg), fexofenadine (180 mg), loratadine (10 mg), desloratadine (5 mg), or levocetirizine (5 mg). 1, 2, 3, 4
Cetirizine is preferred when rapid relief is needed because it reaches maximum concentration fastest among the second-generation antihistamines. 2, 3
These medications work by blocking histamine receptors, preventing the vasodilation and increased vascular permeability that cause hives, and typically provide relief within 30-120 minutes. 3, 5
Critical Safety Consideration
If the patient has any signs of anaphylaxis (difficulty breathing, throat tightness, wheezing, hypotension, or loss of consciousness), immediately administer intramuscular epinephrine 0.3-0.5 mg (1:1000 solution) – do not rely on antihistamines alone. 1, 3, 4
Antihistamines are NOT a substitute for epinephrine in anaphylaxis because they lack the vasoconstrictive, bronchodilatory, and mast cell stabilization properties needed to reverse life-threatening symptoms. 3
In the context of known allergen exposure (e.g., food, insect sting) that previously caused anaphylaxis, even isolated urticaria warrants epinephrine administration to prevent symptom escalation. 1
If Symptoms Persist After Initial Dose
If symptoms are intolerable or inadequately controlled, you can increase the antihistamine dose up to 4 times the standard dose. 1, 2, 3, 4
Consider adding a first-generation antihistamine at night (such as hydroxyzine or diphenhydramine) for additional symptom control and to help with sleep, though be aware of sedating effects. 3, 4
Adjunctive Symptomatic Measures
Apply cooling antipruritic lotions such as calamine or 1% menthol in aqueous cream to provide local symptomatic relief from itching. 2, 4
Identify and avoid aggravating factors including overheating, stress, alcohol, aspirin, NSAIDs, and codeine, as these can worsen urticaria. 2, 3, 4
What NOT to Do
Do not use oral corticosteroids for simple acute urticaria – they have slow onset of action (work by inhibiting gene expression), are ineffective for acute symptom relief, and should be restricted only to severe acute urticaria with angioedema affecting the mouth or airway. 3, 4
Avoid first-generation antihistamines as monotherapy during the acute phase if the patient needs to remain alert, as they cause significant sedation and anticholinergic effects. 3, 6
Do not prescribe NSAIDs if the patient is aspirin-sensitive, as this can exacerbate urticaria. 2, 3, 4
Expected Course and Follow-Up
Most acute urticaria resolves spontaneously within hours to days with antihistamine therapy. 7, 8
If symptoms persist beyond 2-4 weeks, reassess and consider stepping up to higher-dose antihistamines (up to 4x standard dose) before considering this chronic urticaria requiring second-line therapies like omalizumab. 1, 2, 3, 4
Offer the patient at least two different non-sedating antihistamines to trial, as individual responses and tolerance vary significantly between agents. 2, 3, 4