To evaluate the effectiveness of doxycycline (Vibramycin) in acne vulgaris, 62 patients with predominantly inflammatory acne were treated in a double-blind crossover study. The drug was given orally, 100 mg/day, as a single dose every morning for four weeks. No concomitant internal or external therapy was permitted. Noninflamed open and closed comedones were not affected by active or placebo treatment. A good or excellent response in the reduction of inflammatory lesions was obtained in 21 (33%) of the subjects receiving doxycycline, compared to 14 (22%) while receiving placebo. Statistically, the improvement produced by doxycycline was significant, while there was no significant improvement from the placebo.
Plewig G, Petrozzi JW, Berendes U. Double-Blind Study of Doxycycline in Acne Vulgaris. Arch Dermatol. 1970;101(4):435-438. doi:10.1001/archderm.1970.04000040057011