Strategy of acne therapy with long-term antibiotics.

A study of the outcome of conventional antibiotic treatment in 543 patients with acne was performed. All were treated initially with erythromycin 1 g/day and topical 5% benzoyl peroxide. The median improvement at 6 months was 78%, with an interquartile range of 67-90%. Four-hundred and eight of the 492 who completed 6 months' treatment showed over 50% improvement and 247 of the 279 patients treated for a subsequent 6 months with benzoyl peroxide alone, continued to do well. Another subgroup of 174 patients, was continued for 6 months with systemic antibiotic and 5% benozyl peroxide. No significant benefit was gained, however, by maintaining successfully treated patients on a further 6 months of systemic antibiotics. Of the 84 patients who did less well, 18 were given alternative treatment (Diane, isotretinoin). The other 60, subsequently referred to as slow responders, were continued on antibiotics (erythromycin, 31; minocin, 29; cotrimoxazole, 4; trimethoprim, 2) and benzoyl peroxide. Those prescribed minocycline for the second 6 months appeared to have greater benefit (64%) than those receiving erythromycin (57%). This level of improvement was still lower than that seen in those who responded well within 6 months (78%). Of the risk factors analysed, the poorest response occurred in males with truncal acne. Age at presentation, duration and severity did not adversely affect therapeutic outcome. Side-effects were minimal.