This lesser-known acid buffs your skin smooth without ravaging your complexion raw—below, derms explain everything you need to know. Some AHAs can be more intense than others—glycolic acid, for example, has the smallest molecular weight of the bunch, which means it can penetrate the skin’s outer layer quite easily. Mandelic acid, on the other hand, is larger in molecular size (even larger than lactic acid!), which may make it more tolerable for easily irritated skin types. “It’s my absolute favorite AHA—way underrated in my opinion—as it is the most gentle,” says board-certified dermatologist Roberta Del Campo, M.D. “Meaning, anyone can use it, but it is just as effective as other AHAs, such as lactic acid and glycolic acid.” For some general instructions: If you have a mandelic-infused cleanser, you’ll want to follow with soothing ingredients post-wash; avoid any AHAs, BHAs, or retinoids for the rest of the night. And if you have a potent serum, apply it after cleansing and pre-moisturizer as your treatment step. As for masks and peels, these are typically tossed into a routine whenever you want an extra shot of benefits: Apply the formula on clean skin right after your wash, let it sit for a few minutes according to the packaging’s instructions, then wash off and continue with gentle ingredients. Bailey agrees: “Side effects with mandelic acid are similar to other AHAs, in that the acidic pH can irritate sensitive skin,” she says. That said, just make sure to notice when your skin has had enough: Typically, the signs manifest as irritation, redness, inflammation, and sometimes even breakouts.
