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Glycolic acid sounds like something you’d use in a high school chemistry experiment, which is fitting because we’re about to teach you all about it. There are a bunch of reasons to consider using glycolic acid for your skin—it can help with clogged pores, acne, and dark spots from sun damage, to name a few. It’s also suitable for most skin types, and though it can be potent, there are ways to take advantage of its benefits without irritating the heck out of your face (or body).
But before you add a glycolic acid cleanser, serum, or body wash to your cart, it’s important to understand how this master exfoliator works, exactly, and the best ways to use it. To that end, we asked dermatologists to fill us in on the biggest benefits of glycolic acid for skin—and the smartest ways to incorporate it into your routine.
What is glycolic acid?
Glycolic acid is part of a group of chemical compounds called alpha-hydroxy acids (or AHAs). “Alpha-hydroxy acids dissolve the bonds that hold dull, dead cells on the surface of the skin,” Hadley King, MD, board-certified dermatologist and clinical instructor of dermatology at the Weill Medical College of Cornell University in New York City, tells SELF. “Those cells then gently shed, revealing smoother, brighter skin underneath.”1
AHAs, including glycolic and lactic acid, are water-soluble (they dissolve in water) which makes their sloughing powers most effective in the top layer of the skin, where they can help address surface-level issues like fine lines, hyperpigmentation, and blackheads. They’re different from beta-hydroxy acids or BHAs (one common example is salicylic acid, an active ingredient in many acne-fighting products), which are oil-soluble and therefore able to pass through the skin’s natural oils and go deeper into pores to unclog them, Dr. King explains.1
Out of all the AHAs, glycolic acid is made up of the smallest molecules.2 “This means it can more easily penetrate the skin’s surface, which can make it more effective as an exfoliant,” Dr. King says. But that’s also why some people may find it harsh: Because it reaches a slightly deeper, more delicate layer than lactic acid, for example, it can be more irritating to sensitive skin. 2
The main benefits of adding glycolic acid to your skin care routine
So how does all the science above translate to real-world application? Here are some of the ways glycolic acid can change your skin.
A smoother complexion.
You might spot glycolic acid as the active ingredient in chemical peels and exfoliating toners because it helps jump-start the process of, yep, peeling away dead skin in the outermost layer of the skin (a.k.a. the stratum corneum).3 As we mentioned above, this allows a brand new, softer layer to emerge.
The level of exfoliation depends on the concentration of glycolic acid in the product you’re using. In most over-the-counter formulations, the percentage ranges from 5 to 10%, Rebecca Marcus, MD, board-certified dermatologist at North Dallas Dermatology Associates, tells SELF.4 Chemical peels from a dermatologist’s office, on the other hand, often have 30% or higher, which is why professional treatments are more likely to cause flaking. Basically, the higher the concentration of glycolic acid, the more effective it is at penetrating the skin barrier—and the more likely to cause irritation.3
With at-home products, sticking to a concentration of 10% or lower can help prevent inflammation, according to all the dermatologists we consulted. Basically, you want to clear your pores (more on that below) without stripping your skin to the point where it’s raw and inflamed.
Clearer pores and fewer zits.
Because it’s so effective at sloughing off the top layer of skin, glycolic acid can also be beneficial for banishing blemishes. “Chemical exfoliation can help people with acne by clearing dead skin cells and pore-clogging debris,” Dr. Marcus says.5
For anyone who’s both breakout-prone and super sensitive, though, glycolic acid may be too harsh, she notes. Giving your skin breaks between treatments and only applying the exfoliant two or (max) three times a week can help minimize irritation, she adds (start with once a week and see if you can work your way up to two or three treatments without issue).
But if your face still isn’t happy, salicylic acid might be a better exfoliating acne treatment for you, Dr. Marcus says. As we mentioned above, it can penetrate deeper into pores to unclog them, and it’s also been shown to be less irritating than glycolic acid.1
Fewer dark spots from sun damage.
The sun’s UV rays can cause hyperpigmentation (or dark spots). As glycolic acid helps slough off the top layer of dead cells, it can also remove some of that excess pigment (or melanin) in the process, Loretta Ciraldo, MD, board-certified dermatologist and voluntary assistant professor in the dermatology department at the University of Miami Miller School of Medicine, tells SELF.3
In some cases, however, it can have the opposite effect. Especially if you’re prone to hyperpigmentation (a common issue for people with medium to dark brown skin tones, for example, as the body already makes extra melanin, which can lead to dark spots), glycolic acid could make the issue worse. Research suggests that, in high concentrations, it can lead to inflammation, and that damage could trigger hyperpigmentation.6 2
You don’t necessarily have to skip glycolic acid just because you tend to get dark spots, but to be safe and minimize irritation, you should stick with low concentrations (think 5 to 10%), according to Dr. Ciraldo. And again, using it just one or two times a week can also keep skin calmer, Dr. Marcus adds.
Thicker, plumper-looking skin.
While glycolic acid gets busy removing old skin cells, it also promotes the production of new ones. As a result, “it can thicken the skin, stimulate collagen production, and improve tone and texture,” Dr. King explains.3 “Studies have shown, for example, that using a topical glycolic acid cream for six months stimulated a 27% increase in epidermal thickness.”7
Essentially, when glycolic acid strips away the top layer of dead cells, new, healthy ones swoop in to replace them. And thicker, collagen-filled skin can help give you that just-got-a-facial smoothness and plumpness.3
What ingredients are safe to combine with glycolic acid?
You might not want to combine glycolic acid with other AHAs and BHAS, like salicylic acid, because together they can be too strong and cause irritation, according to Dr. King. One exception is fellow AHA lactic acid, since it’s pretty gentle: The two chemical exfoliants can work well together to smooth fine lines and cut back on surface-level dark spots, and you may even find them in the same products, she says.8 “The result of combining the two is smoother and softer skin that’s moisturized and has fewer discolorations,” according to Dr. King.9
Retinol is one active ingredient you probably shouldn’t mix with glycolic acid at the same time, according to Dr. Marcus, since this super strong combo can cause annoying stinging and flaking. Because both ingredients help you ditch layers of dead cells, using them together might strip the skin barrier too much and cause rawness and irritation, Dr. Marcus says—especially if you have sensitive skin to begin with.
How can you work glycolic acid into your skincare routine?
Aside from heeding the advice above (and following package instructions), there are a few more things to be mindful of when adding glycolic acid to your routine. Dr. Ciraldo recommends using it before bed, and not in the morning before you head outside, for one. “Glycolic acid products should have ‘sunburn alerts,’ as they can make you more sensitive to UV rays,” she explains (because, again, they strip away dead cells and expose more delicate skin underneath). That’s why she also suggests using a “broad-spectrum” sunscreen with at least SPF 30 (which is always a smart idea, whether you apply glycolic acid or not).
Speaking of sensitivity, you can also minimize the potentially irritating and drying effects of glycolic acid by coupling it with a moisturizer. “If the glycolic product is a serum, you’ll apply it to cleansed skin before moisturizing,” Dr. Ciraldo says. “If it’s a moisturizer, apply it after a hydrating serum.”
For glycolic acid body products, use the same trick: Slather on a moisturizer right after. “Moisturizing after exfoliation is key to supporting the skin barrier,” Dr. Marcus says. (She recommends lotions and creams with ceramides, specifically, which have been shown to protect your outer layer.)
It might take some time to build up your tolerance to glycolic acid, so if you’re new, go slow at first, Dr. King suggests. She recommends taking an approach that’s similar to skin cycling: Use your glycolic acid product once or twice a week to give your skin time to rest between applications.
Some products to try:
Skin Perfecting 8% AHA Skin Exfoliant
Secret Solution Pro-Glycolic 10% Resurfacing Treatment Toner
Ultra Healing Intensive Lotion
The Body Peel
The bottom line: As long as you can tolerate it, adding glycolic acid to your nightly routine one, two, or maybe three days a week can pay off in the form of smoother, brighter skin. Just remember to moisturize a ton and lather on the SPF to protect your delicate skin barrier and promote a healthy glow.
Journal of Cutaneous and Aesthetic Surgery, Comparative Study of 35% Glycolic Acid, 20% Salicylic–10% Mandelic Acid, and Phytic Acid Combination Peels in the Treatment of Active Acne and Postacne Pigmentation
Originally Appeared on SELF