AHA / Alpha Hydroxy Acid (milk-derived)
The gentlest commonly used AHA — larger molecular weight than glycolic means shallower penetration and less irritation. Uniquely dual-function: exfoliates dead skin AND acts as a humectant, hydrating while it treats. Ideal first AHA for sensitive skin. At higher concentrations treats hyperpigmentation and used in professional peels.
At these concentrations this ingredient should appear above the 1% line on the INCI list. If you see it listed after preservatives or fragrance allergens, the dose is likely too low to work as marketed.
PM 5–12% toner or serum 2–3x per week. Gentler than glycolic — best starting AHA for sensitive or reactive skin. pH 3–4 required for activity.
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