Among all the alpha hydroxy acids, glycolic acid has the deepest body of clinical research behind it, which is part of why it's the most widely used AHA in skincare. At concentrations of 5% or higher, and formulated correctly, it works as an exfoliant. At any concentration, it also acts as a humectant that draws moisture into the skin.
As it clears away dead surface cells, glycolic acid reveals fresher skin underneath, which can visibly soften sun damage, uneven tone, rough or flaky patches, and fine lines. Research also shows it boosts hydration from within by prompting skin to produce more mucopolysaccharides, compounds that raise the skin's own hyaluronic acid levels and improve both texture and resilience.
Glycolic acid does occur naturally, in sugar cane and, less commonly, in sugar maple. But skincare brands almost always use a lab synthesized version instead, since that allows precise control over potency, purity, pH, and stability, all of which determine whether a formula actually performs the way it should.
