Glycolic Acid Polymer
Description
Smallest AHA (MW 76 Da) enabling the deepest epidermal penetration of the AHA class. At <25% produces superficial exfoliation; 25–50% causes keratinocyte discontinuity; 50–75% causes epidermolysis. Disrupts desmosomal cohesion via calcium ion chelation, thinning the stratum corneum and promoting cell turnover. Efficacy governed by free (undissociated) acid concentration per Henderson-Hasselbalch: at pH 3.5 (~68% free acid) vs pH 4.5 (~18% free acid). Also used as pH adjuster.
Function
Properties
Regulatory Status
Glycolic acid is the gold-standard AHA and most evidence-supported chemical exfoliant. Effective for post-inflammatory hyperpigmentation, anti-aging, and acne, but safety and efficacy both hinge on free acid value—total percentage alone is meaningless without pH context. EU SCCS guidance (10% pH ≥3.5) is the operative ceiling for consumer products. Photosensitivity is a documented risk: daily SPF messaging is essential. Greater caution warranted for Fitzpatrick IV–VI due to concurrent lightening of surrounding normal skin at peel concentrations.
CIR (1998, reaffirmed 2013): safe ≤10% at pH ≥3.5 for consumer cosmetics; ≤30% at pH ≥3.0 for professional use. FDA endorses CIR guidance; no binding statutory limit but references CIR in guidance. FDA-sponsored studies confirm up to 18% increased UV sensitivity persisting one week post-discontinuation; SPF labelling strongly advised. Optimal pH range 3.5–4.5.
Ratings
Identifiers
No registry identifiers available for this ingredient.