Review of H1 antihistamines in the treatment of chronic idiopathic urticaria.

Chronic idiopathic urticaria (CIU) can have a profound effect on patient quality of life (QOL). Ideally, any therapy used to treat CIU should be effective across a wide range of doses without causing unwanted side effects; a wide therapeutic window allows the physician to tailor treatment to the individual. Oral H1 antihistamines are the mainstay of therapy for CIU, but agents within this class diverge in their individual therapeutic indices. The literature was reviewed to compare the currently available oral H1 antihistamines regarding their efficacy and safety at a wide range of doses. If sedation and cognitive impairment are considered relevant to treatment selection due to their effect on QOL and safety, then newer-generation agents should be selected over older-generation antihistamines. There are few well-controlled clinical studies in which newer-generation agents have been directly compared. Moreover, there are no evidence-based data demonstrating statistical superiority of one newer-generation agent over another in the treatment of CIU. However, of the newer agents, those that are labelled nonsedating at recommended doses (fexofenadine, loratadine, and desloratadine) should be selected over cetirizine. In cases where the physician judges that a higher-than-recommended dose should be prescribed, or when the patient is likely to take a higher dose, the relative safety profile of these agents demands detailed consideration.