Acids. Depending on who you ask, they’re terrifying, trippy, or totally essential to your skin-care routine — so long as you know your ferulic from your salicylic. Indeed, all acids are not created equal, which is why it’s important to get familiar with the major players before putting them on your face.
Flunked out of chemistry? Don’t worry. We asked three top dermatologists — Heidi Waldorf, MD, associate clinical professor of dermatology at Mount Sinai Hospital, Ariel Ostad, MD, a New York-based board-certified dermatologist and cosmetic dermatologic surgeon, and Annie Chiu, MD, an L.A.-area dermatologist — to break down the distinctions, Acids for Dummies-style. Consider this your cheat sheet to the best brighteners, exfoliators, and acne erasers in the category.
Salicylic AcidAlso known as beta-hydroxy acid, or BHA, salicylic acid is a plant-derived keratolytic agent used for exfoliating clogged pores by removing the top layer of skin. Dr. Waldorf recommends the ingredient for oily types, but says that it can also be used on dry or sensitive skin when it’s combined with hydrating ingredients, like those found in Aveeno's Clear Complexion line. Clear Complexion Foaming Cleanser, $7.49, available at Aveeno Walgreens.
Hyaluronic Acid Hyaluronic acid is the ingredient you want to turn to when your skin becomes drier than the Sahara, as the molecule can hold up to 1,000 times its weight in water. It actually has the ability to pull moisture from the air down through the stratum corneum (or outermost layer of the skin) so that skin stays supple. Hyaluronic acid is obviously a great pick in moisturizers, but look out for it in treatment products as well — according to Dr. Waldorf, the addition of hyaluronic to a typically irritating ingredient like retinol can ease the burn. Kate Somerville Age Arrest Anti-Wrinkle Cream, $90, available at Sephora.
— PAID — Alpha Hydroxy AcidsAHAs are natural exfoliants found in familiar foods, such as sugar cane (glycolic acid), milk (lactic acid), and citrus fruits (citric acid). When applied topically, AHAs can help remove dead skin cells, correct dark spots, and reduce the appearance of wrinkles and pores. But if your skin turns red at just the thought of applying an acid, try a soothing moisturizer spiked with AHAs — as opposed to a highly concentrated peel — like the Avon Anew AHA Refining Cream. Designed for all skin types, it promotes glowy, smoother-looking skin. Avon Anew AHA Refining Cream, $30, available at Avon.
Glycolic AcidIf you’re an adult who still gets zits, consider glycolic acid your skin-saving BFF: It not only helps with collagen production — thereby improving elasticity and youthful plumpness — but it can exfoliate the skin and clear acne, too. “Glycolic acids also improve turnover of dead skin cells that may contain abnormal pigment,” says Dr. Chiu, and because the acid is fruit-derived, it’s typically not as irritating as other exfoliators. If clearing blemishes is the primary goal, look for a glycolic cleanser or peel with salicylic acid in it, too. If your skin is dry or you’re concerned with aging, try a cream. Smoothing Marine Cream, $115, available at Clark's Botanicals Clark's Botanicals.
Lactic AcidDoes your skin get red at the mere mention of acid? Then this is for you. Lactic acid exfoliates dull, dead skin cells like other AHAs do, only it’s a whole lot gentler and less inflammatory because it works on the surface of skin instead of the cellular level, says Dr. Chiu. She adds that it can also minimize fine lines by encouraging collagen growth, and improve skin texture and tone by fading hyperpigmentation and acne scars. If your skin is particularly sensitive, try a soothing cream laced with the stuff; otherwise, Dr. Chiu suggests a scrub or peel. Stem Cell Magic Gel, $75, available at Rodial Saks Fifth Avenue.
Ferulic & Alpha Lipoic AcidsThese two ingredients are antioxidants, meaning that they offset the amount of free radicals wreaking havoc on your skin as a result of environmental stressors such as sun damage and pollution. Plus, Dr. Ostad points out, they aid in collagen production. Gross Ferulic Plus Retinol Wrinkle Recovery Overnight Serum, $88, available at Dr. Dennis SkinStore.
L-Ascorbic Acid (A.K.A. Vitamin C)No wonder derms often refer to vitamin C as a gold-standard antioxidant: The multitasker can help diminish brown spots, decrease melanin production, fight free radicals, and increase collagen production. And though there are different forms of vitamin C, L-ascorbic acid is the most widely used for a reason: “It’s the most well-researched form of vitamin C and the bioactive form in the body,” notes Dr. Chiu, who says it’s a go-to ingredient for fighting photo-aging. Though this acid can be found in all sorts of formulations, from cleansers to brightening masks, Dr. Chiu suggests getting your C in a serum, which is where you’ll find the highest concentrations. Furthermore, go for a serum loaded with other antioxidants: “Ingredients like ferulic acid, green tea, or niaminicide make great teammates because they can actually help ascorbic acid stay stable longer,” she says. Finally, you want a solution that’s packaged in tightly sealed, opaque, or amber housing to help keep destabilizing air and sunlight out of the mix. C-Firma Day Serum, $80, available at Drunk Elephant Sephora.
Retinoic Acid (A.K.A. Vitamin-A Derivative)Like vitamin C, retinoids are another superpower in the anti-aging game. “Retinoic acid is used to combat acne, fine lines, collagen loss, and photo-aging,” Dr. Chiu says. “It slows down melanin production to decrease hyperpigmentation.” Here’s how: When applied to the skin, enzymes in our body work to convert retinols into retinoic acid, which kickstarts collagen production and cell turnover. “That’s what gives you the glowy skin we all dream of,” Dr. Chiu says, noting that the process can take several months and may cause irritation in some. The best way to get your glow on with retinoids? Look for a cream. “An emollient base can help minimize irritation, flaking, and redness,” Dr. Chiu says. If you love oils, try Sunday Riley Luna Sleeping Night Oil, which contains retinol alongside soothing chamomile and blue tansy. RetrinAL Advanced Wrinkle Corrector, $56, available at Avène Avène USA.
Kojic Acid Hydroquinone is a proven weapon against hyperpigmentation, but research shows that the ingredient can be absorbed through the skin, making some squeamish about using it. “Hydroquinone also cannot be used long-term, as it loses its efficacy, and so it’s an ingredient that needs to be cycled off in interims,” notes Dr. Chiu. The botanical backup plan? Kojic acid. “It inhibits tyrosinase, an enzyme that helps produce melanin,” Dr. Chiu says. It’s also more stable than hydroquinone and is safe for long-term use. To boost the efficacy of a kojic-acid product, look for a formulation that includes other botanical brighteners, like licorice extract, vitamin C, and glycolic acid. When brightening specific spots on the face, like dark undereye circles, try a cream. If evening skin tone across your complexion is the goal, try a serum packed with active ingredients. Phyto+, $82, available at SkinCeuticals SkinCeuticals.
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