What is the recommended management for heat urticaria?

Management of Heat Urticaria

The recommended first-line treatment for heat urticaria is second-generation non-sedating H1 antihistamines, with doses that can be increased up to four times the standard dose for inadequate symptom control. 1, 2

First-Line Treatment

• Second-generation non-sedating H1 antihistamines are the mainstay of therapy for heat urticaria, with options including cetirizine, desloratadine, fexofenadine, levocetirizine, loratadine, and mizolastine 1, 2
• Patients should be offered at least two different non-sedating antihistamines, as responses and tolerance vary between individuals 1, 2
• Cetirizine has the shortest time to attain maximum concentration, which may be advantageous when rapid relief is needed for acute symptoms 1
• For inadequate symptom control after 2-4 weeks (or earlier if symptoms are intolerable), increase the dose up to 4 times the standard dose 1, 2
• Studies show that approximately 75% of patients with difficult-to-treat urticaria respond to higher than conventional antihistamine doses 3

Second-Line Treatment

• For urticaria unresponsive to high-dose antihistamines, add omalizumab (anti-IgE monoclonal antibody) at a standard starting dose of 300 mg every 4 weeks 1, 2
• The dose can be increased up to 600 mg every 2 weeks in patients with insufficient response 2
• Allow up to 6 months for patients to respond to omalizumab before considering alternative treatments 1, 2
• Omalizumab is effective in approximately 70% of antihistamine-refractory patients 4

Third-Line Treatment

• For patients who do not respond to high-dose antihistamines and omalizumab within 6 months, add cyclosporine to the antihistamine regimen 1, 2
• Cyclosporine is effective in about 65-70% of patients at a dose of up to 5 mg/kg body weight 1, 4
• Regular monitoring of blood pressure and renal function is required due to potential side effects 2, 5

General Management Measures

• Identify and minimize aggravating factors such as overheating, stress, alcohol, and certain medications (aspirin, NSAIDs, codeine) 1, 2
• NSAIDs should be avoided in aspirin-sensitive patients with urticaria 1, 5
• Cooling antipruritic lotions (calamine or 1% menthol in aqueous cream) can provide symptomatic relief 1, 5
• Patient education about the generally favorable prognosis for eventual recovery is important 1, 2

Special Considerations

• Oral corticosteroids should be restricted to short courses (3-10 days) for severe acute exacerbations but should not be used chronically due to cumulative toxicity 1, 4
• Recent evidence suggests that adding corticosteroids to antihistamines does not significantly improve symptoms in acute urticaria compared to antihistamine alone 6
• First-generation antihistamines may be added at night for additional symptom control, but their sedating effects should be considered 7
• For patients with both heat urticaria and other physical urticarias (such as solar urticaria), a combination of H1 and H2 antihistamines may be beneficial 8

Treatment Algorithm

1. Start with standard dose of second-generation H1 antihistamine 1, 2
2. If inadequate control after 2-4 weeks (or earlier if symptoms are intolerable), increase dose up to 4 times the standard dose 1, 2
3. If still inadequate control, add omalizumab 300 mg every 4 weeks (can increase to 600 mg every 2 weeks if needed) 1, 2
4. If inadequate response to omalizumab within 6 months, add cyclosporine (up to 5 mg/kg body weight) 1, 2

This step-up approach follows the "as much as needed and as little as possible" principle, with treatment adjustments based on the level of disease control 1.