Can on-demand non-sedating antihistamines improve urticaria symptoms? A double-blind, randomized, single-dose study.

Non-sedating H1-antihistamines are the recommended first-line treatment for chronic spontaneous urticaria. While efficacy studies usually apply continuous daily treatment regimens, many patients take their medication on demand. In this randomized, double-blind trial we tested whether on-demand H1-antihistamine desloratadine in standard and higher doses is able to improve the resolution of existing wheals. Symptoms of 29 patients with chronic spontaneous urticaria were followed without treatment on one day and again on another day during the next 3 weeks after a single dose of either 5 mg or 20 mg desloratadine, using different objective measures. While the intervention with both doses of desloratadine was effective in terms of a reduction in hyperthermic skin area, there was no improvement in wheal area and wheal volume compared with no treatment. Wheal numbers were reduced after treatment with 20 mg, but not 5 mg, desloratadine. In conclusion, the beneficial effects of non-sedating H1-anti-histamines given on demand appear to be low. Thus, a preventive treatment strategy should be preferred in chronic spontaneous urticaria.