Glycolic Acid

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.