Tacrolimus in the treatment of severe chronic idiopathic urticaria: an open-label prospective study.

We report the result of a pilot study of low-dose tacrolimus for the treatment of patients with severe chronic idiopathic urticaria (CIU). Nineteen patients with severe CIU were treated with tacrolimus for 12 weeks. Two patients dropped out after 1 week of treatment because of side effects. Following 3 months of treatment, 12 of 17 patients (70.5%) had a clinical response to tacrolimus. In 9 patients, the urticaria had been improved significantly (urticarial score 0-1), enabling them to discontinue antihistamines and, in the case of two patients, corticosteroids. The remaining 3 patients had moderate improvement (urticarial score 2). Three months after the discontinuation of tacrolimus, 3 of 10 responders had a complete resolution of their urticaria (urticarial score 0), 3 had mild deterioration (urticarial score 1-2) controllable by antihistamines alone, and 4 patients had a full relapse (urticarial score 3). Our preliminary results suggest tacrolimus as a treatment option for patients with severe CIU.