Glossary
The smallest alpha hydroxy acid (AHA), derived from sugarcane, with the highest penetration ability of all AHAs due to its tiny molecular size. Glycolic acid exfoliates by dissolving the bonds between dead skin cells, promoting cell turnover, and stimulating collagen production at higher concentrations.
Glycolic acid is the gold standard of chemical exfoliation. Its molecular weight (76 daltons) is the smallest of all AHAs, allowing it to penetrate the skin more deeply and act more effectively than larger AHAs like lactic acid (90 daltons) or mandelic acid (152 daltons). At low concentrations (5 to 10%), it gently dissolves the intercellular glue (desmosomes) holding dead corneocytes together, promoting smooth, even exfoliation. At higher concentrations (20 to 70%, professionally administered), it can reach the dermis, stimulating collagen production and treating deeper concerns like scarring and significant sun damage.
5 to 10%: Daily use exfoliants (toners, serums) for general texture improvement and glow. 10 to 20%: Weekly treatments for moderate texture concerns, fine lines, and mild hyperpigmentation. 20 to 35%: Monthly professional-level peels for significant sun damage, acne scarring, and deeper wrinkles. 50 to 70%: Medical-grade peels administered exclusively by dermatologists for severe photodamage and scarring.
Begin with a low-concentration product (5 to 7%) used 2 to 3 times per week, not daily. Allow 2 to 4 weeks for the skin to acclimate before increasing frequency. Never combine glycolic acid with retinol in the same routine step (both are potent actives that can overwhelm the barrier). Always use sunscreen during glycolic acid use, as the freshly exposed skin cells are significantly more UV-sensitive.
Low concentrations (5-7%) can be used daily by most skin types after a gradual acclimation period. Higher concentrations should be used less frequently (1-3 times per week). If you experience persistent redness, peeling, or stinging that does not resolve between applications, reduce frequency.
Glycolic acid can be used on darker skin tones, but with extra caution. Higher concentrations and over-exfoliation can trigger post-inflammatory hyperpigmentation (PIH) in melanin-rich skin. Start low (5%), use infrequently, and always pair with rigorous sun protection. Some dermatologists recommend mandelic acid (a larger, gentler AHA) for darker skin tones.
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