Quick answer
The most-researched AHA (alpha hydroxy acid) with a long history of safe use; Helps renew skin’s surface, visibly improving several signs of aging; Significantly increases skin’s hydration; New research shows it may protect skin from UV damage Key benefits: Anti-Aging, Evens Skin Tone, Smooths Bumpy Skin.
Glycolic Acid
Updated
Acetic acid, hydroxy-
Purpose
This well-known ingredient is the most-researched alpha hydroxy acid (AHA) and helps renew skin’s surface as well as significantly improve its hydration.
Rating
BEST
Category
Exfoliant, Humectant, pH Adjuster/Stabilizer
INCI Purpose
BUFFERING
Benefits
Alternative Names
Hair Profile
Functions
Helps With
Suitable For
Role
AHA chemical exfoliant. Loosens dead skin cells; encourages healthy cell turnover. 🚩 RED FLAG in Conditioners: Low pH disrupts cuticle adhesion; no length benefit.
At a Glance
The most-researched AHA (alpha hydroxy acid) with a long history of safe use
Helps renew skin’s surface, visibly improving several signs of aging
Significantly increases skin’s hydration
New research shows it may protect skin from UV damage
Article
Glycolic acid is a type of alpha hydroxy acid (AHA) that, like other ingredients in the category, can act as a water-binding agent and, when properly formulated and used in concentrations of 5% or greater, as an exfoliant. While there are several other types of AHA, glycolic acid is by far the one with the most research backing its effectiveness.
In its capacity as an exfoliant, it can help shed dead skin to renew skin’s surface, which results in the improvement of several signs of aging, including sun damage, uneven tone, rough, flaky patches of skin, fine lines, and wrinkles. These benefits are obtainable by choosing a leave-on AHA exfoliant that contains 5–10% glycolic acid when it is used as the sole exfoliating acid. It must also be formulated at a pH between 3-4, which is where optimal exfoliation occurs.
Studies also show that glycolic acid significantly increases skin’s hydration. It does this by helping skin make substances like mucopolysaccharides, which aid hydration by increasing skin’s natural content of hyaluronic acid, which in turn enhances resilience and improves texture.
One exciting new note about glycolic acid: emerging research shows it might even protect skin against UV damage (in addition to reducing its damaging after-effects), though more studies need to be done (and of course it doesn’t replace the need for sunscreen). It’s worth noting that most AHA products do carry a warning about unprotected sun exposure, since the manner in which AHAs exfoliate reveals fresh new skin that can be more susceptible to sun damage.
Glycolic acid occurs naturally in sugar cane, but is most effective when synthesized in a lab, where its potency and concentration are optimized for use in skin care. Using plant sugars, like sugar maple, for their glycolic acid content is an option, but the bulk of the reimized for effectiveness, purity, stability, and pH, all critical to getting effective glycolic acid products.
See: Malic Acid, Tartaric Acid, Lactic Acid
References