Double-blind comparison of cetirizine and placebo in the treatment of seasonal rhinitis.

: The efficacy and safety of cetirizine were evaluated in 419 patients with seasonal allergic rhinitis. Using a 4-way, double-blind randomization schedule, patients were given a 1-week course of once daily cetirizine (5, 10, or 20 mg) or placebo. Patient and physician efficacy ratings corresponded, indicating superiority of cetirizine to placebo (P less than .05) in reducing symptom severity scores for sneezing, rhinorrhea, ocular pruritus, nasal pruritus, watering of the eyes, and redness of the eyes. All cetirizine doses achieved higher efficacy ratings (72.7%, 79.2%, and 75.7%, respectively) than placebo (52.9%; P less than .05) by the physician's global assessment. Cetirizine was well tolerated, with sedation being the most common adverse experience, increasing in frequency at higher doses. A dose-response relationship was evident for selected symptoms, and the once daily 5-mg dose was found to be an effective minimum dose.