Lactic acid is an alpha hydroxy acid which is found in certain sour dairy products such as yogurt and cheese. Lactic acid is gentler on the skin than glycolic acid and does a better job of treating age spots than fine lines orFemtrexwrinkles. Lactic acid is also very good at keeping the skin more moisturized as it is a humectant which pulls moisture from the air and holds it in the skin. Lactic is very good as a lighter peel used for sensitive skin.