The mechanism of action of chemical peels agents is to accelerate the turnover of epidermal layers and remove pigmented upper layer keratinocytes, leading to loss of melanin granules.

Postinflammatory hyperpigmentation is the most common complication, especially in dark-skinned individuals. Other adverse reactions include postpeel erythema, infection, and aggravation of melasma.

Exfoliants such as alpha-hydroxy acids have been shown to lighten melasma, solar lentigines, and postinflammatory hyperpigmentation.

Glycolic acid is derived from sugar cane and is used as an ingredient in skin-lightening products in low concentrations. It may also be used as a peeling agent in concentrations of 30-70% to increase the efficacy of other lightening agents such as hydroquinone by removal of the epidermis, thus enhancing the penetration of hydroquinone. Repeated peels every 2-3 weeks are necessary to attain significant lightening. In an Indian study of 40 patients with skin types III-IV with moderate-to-severe melasma, glycolic acid peels were used in addition to a modified Kligman hydroquinone formula in a 21-week open pilot study. Eighty percent of patients in the peel group noted excellent improvement, while only 60% of the control group had the same improvement.

Other chemical peels include 50% trichloroacetic acid (TCA) peels and 20-30% salicylic acid peels used for various pigmentary disorders, including melasma, on darker skin types. A clinical trial on TCA peels in 20 patients with melasma reported 55% of patients experienced good clinical response, with no significant complications reported.

Superficial and medium-depth peels with salicylic acid have shown efficacy and were well tolerated in darker skin types when combined with hydroquinone.