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Glycolic acid is one of those ingredients that falls into the "oldie but goodie" category of skincare superstars. While it's by no means the newest or trendiest ingredient out there—it's been used in dermatology for over three decades—it is a tried-and-true staple, favored by dermatologists for its long list of proven benefits. And, surprisingly, those benefits aren't limited to exfoliation. Ahead, dermatologist Kenneth Howe, MD, of Wexler Dermatology in New York City, and New York-based dermatologist Kavita Mariwalla, MD, explain exactly what makes this acid so unique and why it deserves a role in your skincare routine.
Meet the Expert
Type of Ingredient: Alpha-hydroxy acid
Main Benefits: Acts as a chemical exfoliant by loosening the bonds between dead skin cells while helping to treat acne. Glycolic acid also stimulates collagen production and acts as a humectant, attracting moisture to the skin.
Who Should Use It: Glycolic acid is well-tolerated by most skin types and is gentle enough that usually, even those with sensitive skin can use it, says Howe.
How Often Can You Use It: This depends largely on your skin and the particular product you're using, but in certain situations, it can be used daily.
Works Well With: Other humectants, such as hyaluronic acid, though it's also often combined with lightening ingredients such as kojic acid or hydroquinone.
Don't Use With: Be especially cautious when pairing it with other acids and retinoids, cautions Mariwalla.
What Is Glycolic Acid?
"Glycolic acid is an alpha-hydroxy acid derived from sugarcane," explains Howe. Because it comes in various strengths, it has various applications, ranging from over-the-counter, leave-on creams to medical-grade, chemical peels that only dermatologists should apply, adds Mariwalla. Looking at the big picture of all of the different types of acids out there, it falls on the gentler end of the spectrum, which is what makes it a good option for almost anyone. However, as far as AHAs specifically go, it's one of the stronger, more potent ones; because it has the smallest molecular weight of any alpha-hydroxy acid, it penetrates the skin more easily, explains Howe. In other words, it's more effective than other common AHAs such as lactic acid or malic acid, though subsequently not quite as gentle.
Benefits of Glycolic Acid for Skin
Essentially every acid acts as a chemical exfoliant, but glycolic acid has several other notable attributes.
- Removes dead skin cells to reveal softer, smoother skin: Glycolic acid works by loosening the binding between dead skin cells, allowing them to slough off, says Mariwalla. (If you want to get technical, the term for this is desquamation.)
- Is an effective acne-fighter: By encouraging the shedding or peeling of cells on the skin's surface and those lining the pores, glycolic acid prevents the formation of clogged pores—the main factor that contributes to acne, says Howe.
- Works deeper in the skin to stimulate collagen production: Glycolic acid's effects aren't limited to the skin's surface. It's also been found to work on the skin's deeper layers to promote collagen synthesis, which is why it's considered a good anti-aging ingredient, Howe says. (Mariwalla notes, however, that unlike its exfoliating effects, the youth-boosting benefits come with continued use over time. In other words, while you'll see smoother, more even skin pretty much instantly, it'll take time to notice an improvement in lines and wrinkles.)
Side Effects of Glycolic Acid
At the end of the day, an acid is an acid. And that means that there's always going to be the potential for some redness, irritation, and peeling, particularly if your skin is sensitive to start. (Howe says that those who are eczema-prone or have a dehydrated complexion are especially at risk.)
How to Use It
Not all glycolic acid products are created equal, so your best bet is always to follow the directions for the particular product you're using. Some rely on glycolic acid alone, though many pair it with other acids specially formulated to not irritate. It's also worth noting that, even if a product specifies a concentration of glycolic acid (most OTC options contain less than 15%), this figure isn't a true indicator of how strong or effective it will be, says Mariwalla. "That's determined by the free acid value, which has to do with both the amount of glycolic acid and the pH of the product, and often times isn't listed," she says. If you want to err on the side of caution, stick with products that contain less, but keep in mind, it's best to start using glycolic acid gradually and build up frequency as your skin adapts. Reserving application for your nighttime routine is also a good approach since it may make your skin more sensitive, Mariwalla adds.
The Best Glycolic Acid Products
"I love the glow that this cream imparts, and the results are both consistent and immediate," says Mariwalla of one of her top picks. Unlike many other products, it lists the free acid value, so you can know for certain that you're getting a 10% concentration of glycolic acid. Thanks to the addition of a soothing complex, it's gentle enough for nightly application.
Howe recommends this toner for oily skin. It combines glycolic acid (and other AHAs) with beta-hydroxy acids, though it's specially formulated to avoid irritation. Swipe it across your skin post-cleansing, either all over or just on oily or breakout-prone spots like the T-zone.
Howe says this brand excels when it comes to "exploring the therapeutic potential of glycolic acid," and this serum is his favorite of all their offerings. It combines glycolic acid with peptides and fruit stem cell extracts to combat multiple aging signs in various ways.
According to Howe, the shorter the amount of time glycolic acid is in contact with your skin, the lower the likelihood for irritation. In other words, a wash-off cleanser is less likely to be problematic than a leave-on cream—a good gateway product. This one, in particular, is a great option. It's an oil-free formula that relies primarily on glycolic acid, along with a few other AHAs, to both cleanse effectively and exfoliate ever-so-slightly.
Because this product contains multiple different types of acids, it is, "an intense treatment," says Mariwalla, though a highly effective one. Glycolic acid (the second ingredient on the list) is paired with lactic and citric acids, all in a texture that Mariwalla lauds for being lightweight and non-sticky.
Both Howe and Byrdie editors are big fans of this serum, which blends glycolic acid with several other AHAs, as well as salicylic acid, a beta-hydroxy acid. It may sound intense, but the addition of raspberry fruit extract helps soothe the skin, while that powerful lineup of acids addresses everything from wrinkles to clogged pores and even dark spots.
While Mariwalla generally recommends reserving glycolic acid for nighttime use, she says this daytime serum is the exception to the rule, thanks to its unique formulation. Along with glycolic acid, it boasts a litany of antioxidants to protect skin from damaging free radicals—a great option for anyone looking to prevent or treat signs of aging. Be sure to follow-up with a broad-spectrum sunscreen.