Are Nonsedating Antihistamines Really Nonsedating?

Second-generation antihistamines have become extremely popular because they are thought to be less sedating than their older counterparts. In this meta-analysis, researchers in Denver examined sedation and psychomotor impairment that resulted from either the first-generation antihistamine diphenhydramine or second-generation antihistamines (e.g., cetirizine, fexofenadine, loratadine). Eighteen randomized blinded studies were identified.

Both diphenhydramine and second-generation antihistamines caused significantly more psychomotor impairment and sedation than placebo did. Moreover, diphenhydramine caused significantly more psychomotor impairment and sedation than did the second-generation antihistamines. However, there were exceptions: In so…