Combination of azelaic acid 5% and erythromycin 2% in the treatment of acne vulgaris.

INTRODUCTION: Acne vulgaris is a common problem, particularly among adolescents, which is usually resistant to monotherapy. We evaluated the efficacy and safety of a combination of azelaic acid (AA) 5% and erythromycin 2% gel (AzE) compared with AA 20% or erythromycin 2% gels in facial acne vulgaris. METHODS: We conducted a 12-week, multicenter, randomized double-blind study on 147 patients with mild-to-moderate acne vulgaris. Four treatment group were determined (placebo, erythromycin, AA and AzE) and followed in 4-week intervals for 12 weeks, except the placebo group which was changed to routine treatment after 4 weeks. RESULTS: The combination of AA 5% and erythromycin 2% gel significantly reduced the number of papules, pustules and comedones compared with placebo (p < 0.001), erythromycin 2% (p < 0.01) or AA 20% (p < 0.05). The incidence of adverse effects observed in patients treated with AzE (27%) was less than that with erythromycin 2% (54%) and AA 20% (45%). CONCLUSIONS: The combination of AA 5% and erythromycin 2% produced more potent therapeutic effects in comparison with erythromycin 2% or AA 20% alone, and with fewer side effects.