Alpha hydroxy acid (AHA) is a skincare workhorse that offers different benefits depending on its concentration. At lower levels AHAs like glycolic acid and lactic acid work as moisturizing agents; at higher levels, they serve as exfoliants. Research shows that this family of acids can help reverse the effects of aging, dry skin, and skin pigmentation issues. AHAs are most effective in leave-on products like serums, and they should be worn with sunscreen as they are known to increase sensitivity to sunlight.