The efficacy and safety of Ketotifen (Zaditen®) were studied in 83 patients with perennial rhinitis at the ENT departments of hospitals in Sendai, Japan. Each patient took a 1mg capsule of Ketotifen (Zaditen®) twice daily for at least 4 weeks. The rate of effectiveness of Zaditen was 88.6% with slight to marked improvement. About half of them responded to treatment in the first week, and 97.1% of them within 4 weeks after the start of treatment. The only side effect worthy of mention was drowsiness during the treatment, but it was usually transient.
