Healthy skin starts with effective exfoliation. As dead cells accumulate on the surface, skin becomes dull, rough, and less responsive to active ingredients. The skin is in a constant state of renewal, continuously shedding dead cells from the surface while replacing them with newly formed cells from the lower epidermal layers.
As cells migrate upward, they harden, die, and eventually flake away, completing a full turnover cycle. This cycle slows significantly with age. Infants renew skin in as little as 14-28 days. Young adults may take 28–40 days. Turnover progressively lengthening through each decade of life, exceeding 60 days for adults over 50 years old.1,2,3
Chemical exfoliants such as alpha and beta hydroxy acids (AHA and BHA) gently dissolve this buildup to reveal fresher, smoother, more radiant skin. AHAs include glycolic and lactic acid, and BHAs include salicylic acid. There is a more recent shift towards polyhydroxy acids (PHAs) since they are larger molecules, offer additional antioxidant and humectant benefits and can be used in more sensitive skin applications.4
1. Van Geloven, A‑M. Epidermal Cell Turnover: Debunking the 28‑Day Myth (2024).
2. Biology Insights. How Long Does It Take to Shed All Your Skin? (2025).
3. Stamatas, G. N., et al. Infant Skin Physiology and Development During the First Years of Life (2011).
4. Raymond, D., McDonough, D. Personal Care Magazine. The Shift Towards Polyhydroxy Acid Exfoliants. February 2026, p. 22.