Combined micro-needling with topical metformin versus micro-needling with topical placebo in the treatment of melasma: a concurrent split-face study.

Melasma is an acquired dysfunction of melanogenesis, that poses a major therapeutic challenge and tends to recur after therapy. Several combination therapies are being tested nowadays for the treatment of melasma, with promising results. Metformin, an anti-diabetic medication, seems to inhibit melanogenesis by different mechanisms. In addition, there has been a long-term improvement in melasma after microneedle therapy. To evaluate the potential therapeutic role of topical metformin combined with micro-needling for the treatment of melasma. Eighteen patients with melasma received treatment in split-face manner, right side with micro-needling and topical metformin, while the left side was treated with micro-needling and topical placebo for four sessions at 2-week intervals. Hemi-mMASI score was used for the final evaluation of results. The variability pattern in Hemi-mMASI score between both sides revealed significant reduction in the right side (micro-needling + metformin), as compared to the left side (micro-needling + placebo) (2.39 ± 1.42 vs 4.72 ± 1.27, p = 0.001). The effectiveness of topical metformin in the management of melasma could be significantly improved by pretreatment with micro-needling as a combined therapy, without any apparent side effects.