Topical use of tetracycline in the treatment of acne: a double-blind study comparing topical and oral tetracycline therapy and placebo.

A group of 75 subjects with moderate or severe acne was divided by random selection into three treatment groups. One group was treated with a topically applied placebo liquid and with 500 mg of orally administered tetracycline hydrochloride daily; one group received orally administered lactose capsules and topically applied placebo liquid each day; and one group was treated with orally administered lactose capsules and with a topical preparation containing tetracycline hydrochloride and n-decylmethyl sulfoxide, an agent intended to enhance antibiotic penetration. At the conclusion of the 13-week study and at several points during the study, the conditions of the subjects receiving topically or orally administered tetracycline hydrochloride were significantly (P less than .05) more improved than the conditions of the subjects receiving lactose capsules and the topically applied placebo liquid. However, there was no significant difference between the effects of topically and orally administered tetracycline hydrochloride.