Lactic acid – an alpha hydroxy acid (AHA) – is a natural exfoliating ingredient in skincare products. Because it’s derived from milk, it is often suitable for sensitive skin, or for people who suffer from skin conditions such as rosacea or acne. In lactic acid exfoliation, the outer layer of skin is encouraged to shed, exposing healthier skin cells from underneath. Healthier cells are also more hydrated, which in turn offers a smoother texture of the skin. It’s used in cleansers, acne products and anti-aging formulas. Many chemical peels also use lactic acid to remove mild marks, scars and discoloration. If you’re just starting out with a product that has lactic acid, it may be wise to use it every other day at first and then work your way up to daily use. And no matter what lactic acid product you use, increased sun sensitivity is often an issue, so limit your time in the sun and use sunscreen.