Alpha hydroxy acids, often called AHAs, are naturally occurring chemical compounds derived from fruits and other foods. Some common AHAs include glycolic acid (sugar), lactic acid (milk), and citric acid. AHAs are often found in anti-aging creams, masks, cleansers, and chemical peels that claim to reduce wrinkles and tighten skin.
AHAs penetrate the skin's surface and work much like exfoliators, dissolving elements that bind dead skin cells. Though AHAs are generally safe, they can cause redness, irritation, flaking, and increased sensitivity to sun, so be sure to slather on the sunscreen.