Low-Dose Doxycycline for Moderate Acne

Home>
Specialty Care>
Dermatology>
Summary and Comment

Low-Dose Doxycycline for Moderate Acne

This regimen may be the safest approach to antibiotic treatment of acne.

The usual dosage of oral doxycycline for treating acne is 50 mg to 100 mg twice daily. This agent presumably works by decreasing the population of the skin bacterium Propionibacterium acnes, which is thought to be an important element in the pathogenesis of acne. Previous research has suggested other potential actions of doxycycline, including down-regulation of inflammatory mediators and inhibition of P. acnes-derived lipase, with a resultant reduction in levels of follicular-free fatty acids. These effects may occur at doses of doxycycline that are too low to inhibit bacterial growth. In this manufacturer-sponsored, multicenter, double-blind study, investigators examined the effect on moderate facial acne of a 6-month course of 20-mg doxycycline twice daily compared with placebo.

Among the 40 patients who completed the study, the mean reduction in inflammatory lesions and comedones was 52% in the doxycycline group versus 18% in the placebo group, a significant difference. There were no changes in either group in the composition of the surface skin flora or in antimicrobial susceptibility.

Comment: Whether doxycycline improved acne in these patients by an antimicrobial effect on organisms in the follicles or by another action is unclear, but this low-dose regimen appears to treat acne effectively without altering the antimicrobial susceptibility of the skin flora. Furthermore, previous trials of low-dose doxycycline have demonstrated no change in the antibiotic sensitivity of bacteria in the gastrointestinal and genitourinary tracts. This therapy may be the safest approach to using antibiotics for treating acne (see also JW Dermatology May 14 2003, and Arch Dermatol 2003; 139:467).

— Jan V. Hirschmann, MD

Published in Journal Watch Dermatology May 28, 2003