Mandelic Acid 10% + HA offers superficial dermal peeling that is gentler than other alpha hydroxy acids. The molecular weight of mandelic acid is 152.1 daltons which is larger than other alpha hydroxy acids (glycolic acid is 76.0 daltons, for example). This larger size allows mandelic acid to penetrate the skin more slowly which in turn makes it very gentle and suitable for all skin types. You don't need a concentration of more than 10%, because then you would simply be achieving an indirect peeling strength that is more easily offered through lower percentages of glycolic acid.Contraindications: This formula should not be used on sensitive, peeling, or compromised skin. Please refer to additional sun protection note and other warnings in provided Directions.Note: While exfoliating acids can result in quick visible benefits, we generally suggest the use of indirect forms of skin exfoliation in favour of direct forms such as this formula due to potential inflammation and sensitivity associated with acids. Please refer to NIOD's Non-Acid Acid Precursor for such a suggested formula.