Chronic unremitting urticaria: is the use of antihistamines above the licensed dose effective? A preliminary study of cetirizine at licensed and above-licensed doses.

Recently, several authors have suggested an off-label increase of antihistamine dosage should be given to patients with chronic urticaria (CU) not responding to the usual, recommended doses, in order to gain better control of the disease. However, this recommendation is not evidence-based. The objective of this study was to assess the effectiveness of increased doses of antihistamines in patients with CU showing poor control at recommended doses. In total, 22 adult patients with moderate/severe CU not controlled with the usual antihistamine doses were studied. These subjects recorded urticaria severity on a visual analogue scale (range 0-10) for 2 weeks. During the first week, they were treated with cetirizine at the licensed dose (10 mg/day), and with a three-fold increased dose (10 mg x 3/day) during week 2. Only 1 patient (5%) responded satisfactorily to the increased dosage of antihistamine; in the remaining 21 subjects, urticaria scores did not change, and these patients had to be treated with steroids, ciclosporin, and in 1 case with cyclophosphamide. Disease control was eventually gained in all cases. This study suggests that the proportion of patients with severe CU that may gain a better control of their disease with high, off-label doses of antihistamines is probably small, and that most patients will eventually have to undergo more aggressive treatments.