Clinical investigation of terfenadine, a non-sedating antihistamine.

Terfenadine was evaluated for the relief of symptoms in patients with allergic pollinosis on a double-blind basis. Terfenadine 20 mg tid was as effective as Chlorpheniramine maleate 4 mg tid. Chlorpheniramine consistently showed a higher incidence of sedation than placebo. None of the terfenadein dosage schedules up to 200 mg tid caused sedation significantly different from that of placebo. Terfenadine appears to be the first antihistamine to lack significant central nervous system effects.