Everything You Need to Know About Glycolic Acid, Explained
It's the workhorse of exfoliating acids.
Credit: Getty Images
No hyperbole: Glycolic acid changed my life. After years of alternating between salicylic acid and benzoyl peroxide, brushing off flakes caused by retinol, and piling on pounds of concealer to cover an errant breakout, I was finally able to walk outside without makeup and not feel self-conscious about my acne-prone skin. If I were to get into the lobbying game, I would sell my damn soul for glycolic acid. Were I to run for president (of whatever), my slogan would be Glycolic Acid Deserves More Credit.
The major advantage of glycolic acid is that it does more than treat breakouts. The ingredient can also tackle hyperpigmentation, dullness, and signs of skin aging, such as lines and wrinkles, without breaking a sweat. But don't just take my word for it. Here's a breakdown of the most common questions about glycolic acid and what exactly makes it such a great ingredient.
So...what exactly is glycolic acid?
Glycolic acid is a type of alpha-hydroxy acid (or AHA) that's derived from sugar cane. It joins other acids you might recognize, such as lactic acid (derived from sour milk and purportedly a favourite of Cleopatra's), tartaric acid (from grapes), and citric acid—which, you might guess, comes from citrus fruits.
But it's unique. "Of the AHAs, glycolic is the simplest in structure and the smallest; it has the lowest molecular weight," says Kenneth Howe, M.D., a dermatologist at Heyday in NYC.
What does glycolic acid do for your skin?
First and foremost, glycolic acid is an exfoliant. It helps shed dead skin cells and reveal the newer, brighter layers underneath by acting on the stratum corneum (the outermost layer of skin). "Normal, intact stratum corneum consists of tightly packed layers of dead skin cells that are tightly bonded together," says Dr. Howe. "Glycolic acid loosens these bonds." With their glue dissolved by glycolic acid, those tough, rough layers of dead skin cells can more easily slough away.
But because glycolic acid is so small, it can get deeper into your skin too, where it does some serious work. "Glycolic acid stimulates fibroblasts in the dermis to produce increased amounts of collagen," says Dr. Howe. And by stimulating collagen production, it helps skin feel firmer and minimizes fine lines and wrinkles. Between the superficial action on your stratum corneum and the work it does below, "your skin will feel smoother and look more radiant and even-toned," Shapiro says.
Great! How should I use glycolic acid in my routine?
As with any exfoliant, it's best to start small if you have sensitive skin or are prone to irritation. For this, Shapiro recommends using it in a face wash. "A glycolic cleanser can get your skin used to it, rather than diving straight into a leave-on glycolic product if you are unsure whether your skin can tolerate it," she says. Try one that pairs it with hydrating ingredients, like Glow Recipe Blueberry Bounce Gentle Cleanser ($34), which includes hyaluronic acid.
If you know your skin is up for it, try it in a peel. "I feel glycolic acid is most effective when administered as a chemical peel done in a health care practitioner’s office," says Dr. Howe. "The medical-grade peel pads we use are stronger, with more potent effects, and many people get better results with stronger treatments done intermittently—once a month, say." He also thinks patients do well with milder exfoliation more frequently, as with an at-home peel pad. I personally swear by Dr. Dennis Gross Alpha Beta Universal Daily Peel ($88) has a cult following for a reason.
Will glycolic acid work for my skin type?
"It's best for normal, combination, and oily skin types," says Shapiro. But as with anything, glycolic acid is not for everyone. "People with dry, highly sensitive skin often react to it with irritation," says Dr. Howe. "Any form might irritate them, whether it’s in a topical product, a home-use peeling pad, or an office-based peel procedure."
There's also a seasonal factor to consider. In the winter months, when your skin's barrier function might be compromised (and therefore skin appears dry or chapped), this can allow for deeper penetration and, in a nutshell, irritation. Conversely, sun exposure can increase the turnover of skin and therefore is naturally exfoliating. In the summer months, that makes glycolic acid riskier, since it can make you sensitive to sunlight. (Although, no matter the time of year or where you're going, slathering on SPF is essential—especially after exfoliating.)
Are there any ingredients you shouldn't pair it with?
It all depends on how well your skin can stand up to harsh products. If it took you weeks to acclimate to retinol, then adding glycolic acid on top of it is likely too much for you. But this can still be problematic even if you think your skin is tough. "The retinol products speed up cell turnover in the skin, resulting in a functional exfoliating effect," says Dr. Howe. "This thinning of the outer layer of the skin increases the penetration of glycolic acid, and with that the likelihood of irritation."
While glycolic acid can be beneficial in conjunction with other, gentler exfoliators like salicylic acid, as in acne-fighting glycolic treatments like Pixi Beauty Glow Peel Pads ($22), combining it with more hard-core exfoliating ingredients (including retinol) is best avoided.
Are there any side effects you should be aware of?
Since it's a powerful acid, you run the risk of skin irritation or burns. "But not what happened to Samantha in Sex and the City,” says Dr. Howe. "I have never seen a reaction that severe, not from glycolic acid." Overall it's actually very safe, so much so that a derm can do a glycolic acid peel to treat acne during pregnancy.
Another advantage? It has a built-in safeguard. "Glycolic acid is immediately neutralized upon contact with water," Dr. Howe says. Not only can you rinse it off if you feel tingling, but even if it penetrates deeply into your skin, it eventually reaches the water in the dermis. There it's neutralized and won't go any further.