Lactic acid versus glycolic acid peels for melasma

Forty people with melasma were randomly assigned to four peel sessions two weeks apart with either 80% lactic acid or 50% glycolic acid, and scored using a standard melasma severity index at the start and at ten weeks. The glycolic acid group improved more: a median score drop of 2.85 against 1.8 for lactic acid, a difference that was statistically significant. Side effects were similar in both groups. This matters because lactic acid is often presented as the gentler peel that works just as well. In the one randomised comparison available, it did not — and it was no gentler either.