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.
Glycolic Acid References
Molecules, April 2018, 23(4), ePublication | DNA Cell Biology, February 2017, pages 177-187 | Journal of Clinical and Aesthetic Dermatology, October 2015, pages 21-26 | BioMed Research International, 2015, Volume 2015 | Dermatology Research and Practice, February 2015, Volume 2015
Our team reviews ingredient research and uses up-to-date evidence to rate ingredients based on the categories below.
Best
Ingredients with the most rigorous and convincing evidence. These are the standouts backed by consistent findings across independent, peer reviewed clinical research.. When we call an ingredient Best, it has earned that distinction through genuine, reproducible proof that it improves skin.
Good
Reliable, well tolerated ingredients that do their job without complaint. They may not carry the headline benefits of a Best rated active, but they hydrate, stabilize a formula, or support the ingredients around them in ways that make a real difference in how a product performs and feels.
Average
Ingredients that are perfectly safe and serve a clear function, typically as an emollient, thickener, or filler, but do not offer any meaningful skin benefit beyond that basic job. Not a red flag, just not a reason to choose one product over another.
Bad/Worst
Ingredients with documented potential to irritate skin, disrupt the barrier, or trigger sensitization in some users, often synthetic fragrance, drying forms of alcohol, or certain essential oils. Not automatically a dealbreaker for every skin type, but worth knowing about before you commit to a product.
