In the article "Efficacy of Glycolic Acid Peels in the Treatment of Melasma,"1 the authors conclude that the addition of 4 glycolic "peels" did not enhance the hypopigmenting effect of hydroquinone treatment. A chemical peel is a procedure in which the skin peels after treatment with a chemical solution. In this case, the authors reported the application of 20% and 30% glycolic acid pads did not result in epidermolysis and indeed only produced erythema.
Coleman III WP, Brody HJ. Efficacy of Low-Strength Glycolic Acid Application in the Treatment of Melasma. Arch Dermatol. 2003;139(6):811. doi:10.1001/archderm.139.6.811-a