Physical exfoliation — scrubs, brushes, microdermabrasion — acts mechanically on the skin surface. Chemical exfoliation uses hydroxy acids to dissolve corneodesmosomes (the protein bonds holding desquamating cells together) or directly acidify the SC, accelerating natural cell turnover without friction-induced trauma. The result: smoother texture, reduced comedones, improved hyperpigmentation, and with prolonged use, stimulation of dermal collagen synthesis at concentrations above peel threshold. The key to effective chemical exfoliation is matching the acid type and concentration to the skin's needs and tolerance. Our skin care catalog includes professional-grade exfoliant products for clinical use and retail recommendation.
Alpha-Hydroxy Acids (AHAs)
AHAs are water-soluble acids that work at the skin surface and outer SC layers through acidification and corneodesmosome dissolution. Glycolic acid (the most studied) has the smallest molecular weight (76 Da), providing the deepest SC penetration of any AHA — validated photoaging efficacy at 8–12% in consumer products and 20–70% in professional peels. Lactic acid (molecular weight 90 Da) penetrates less deeply than glycolic but has additional humectant properties (a natural NMF component) making it gentler and better for dry/sensitive skin. Mandelic acid (largest molecular weight AHA, 152 Da) penetrates least and is the best-tolerated AHA for sensitive skin and darker Fitzpatrick skin types (lower post-inflammatory hyperpigmentation risk). Malic acid and citric acid have significant evidence of photoaging improvement at professional peel concentrations.
Beta-Hydroxy Acids (BHAs)
Salicylic acid is the only BHA used in skincare. Its lipid solubility distinguishes it fundamentally from AHAs — salicylic acid penetrates the lipid-rich sebaceous follicle environment, making it uniquely effective for comedonal acne, clogged pores, blackheads, and oily/acne-prone skin. At 0.5–2% (OTC concentration), salicylic acid reduces microcomedo formation, improves acne, and modestly improves texture. At 20–30% (professional peel), salicylic acid produces deeper exfoliation with anti-inflammatory benefits making it preferred for acne-prone and darker skin types where AHA peels carry higher PIH risk.
Polyhydroxy Acids (PHAs): The Sensitive Skin Option
PHAs (gluconolactone, lactobionic acid) have larger molecular weights than AHAs, limiting SC penetration and producing gentler exfoliation with minimal irritation. PHAs also have humectant and antioxidant properties not shared by simpler acids. Evidence: comparable efficacy to glycolic acid for texture and mild hyperpigmentation with significantly lower irritation in direct comparison studies — appropriate for rosacea-prone, post-procedure, and sensitive skin types that cannot tolerate traditional AHAs. Our skin care section carries exfoliant products across AHA, BHA, and PHA categories for clinical recommendation and retail use.
