Context: The generalized type of social phobia (social anxiety disorder) is a severe and often disabling form of social anxiety that affects approximately 5% of the general population. Earlier research has shown monoamine oxidase inhibitors or benzodiazepines to be effective in treating this condition, but neither has achieved widespread use.

Objective: To compare the efficacy of paroxetine, a selective serotonin reuptake inhibitor, with placebo in adults with generalized social phobia.

Design: Twelve-week, multicenter, randomized, double-blind trial.

Setting: Thirteen centers across the United States and 1 in Canada.

Participants: Between April 13, 1995, and February 28, 1996, 187 persons meeting Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for generalized social phobia were randomized (and 183 returned for at least 1 efficacy assessment) to treatment.

Intervention: After a 1-week, single-blind, placebo, run-in period, patients received a double-blind, 11-week course of either paroxetine or matching-image placebo. The initial daily dosage of paroxetine (or placebo) was 20 mg with increases of 10 mg/d weekly (flexible dosing to a maximum of 50 mg/d) permitted after the second week of treatment.

Main outcome measures: Number of responders based on the Clinical Global Impression Global Improvement Item ("much improved" or "very much improved"); mean change from baseline on the Liebowitz Social Anxiety Scale total score.

Results: Fifty (55.0%) of 91 persons taking paroxetine and 22 (23.9%) of 92 persons taking placebo were much improved or very much improved at the end of treatment (odds ratio [OR], 3.88; 95% confidence interval [CI], 2.81-5.36). Mean Liebowitz Social Anxiety Scale total scores were reduced by 39.1% (the mean baseline score of 78.0 declined by a mean of 30.5 points at follow-up) in the paroxetine group compared with 17.4% (the mean baseline score of 83.5 declined 14.5 points at follow-up) in the placebo group, a difference of 21.7% (95% CI, 8.7%-34.7%) favoring paroxetine.

Conclusions: Paroxetine is an effective treatment for patients with generalized social phobia. Short-term (ie, 11-week) treatment results in substantial and clinically meaningful reductions in symptoms and disability. Future research should test whether these may be further reduced by extended treatment or supplementation with specific educational-cognitive-behavioral techniques.