What Is Glycolic Acid?

Glycolic acid is an alpha hydroxy acid (AHA) derived from sugar cane that chemically exfoliates the skin and boosts collagen. As a result, adding glycolic acid to your skincare routine can help improve skin texture, smooth wrinkles, and unclog pores.12
You can find glycolic acid in over-the-counter (OTC) products like toners, serums, treatment creams, and peels. You can also visit a dermatologist for a medical-grade glycolic acid chemical peel for more potent results. Here's everything about the benefits and risks of using glycolic acid skincare. 

How Does Glycolic Acid Work?
Glycolic acid is easily absorbed into your skin because it has extremely small molecules compared to other AHAs. Once absorbed by your skin, it acts as a chemical exfoliator and dissolves dead skin cells on the surface of your epidermis—the top layer of your skin. Glycolic acid sheds away dead skin cells quickly by increasing cell turnover, allowing new skin cells to replace old skin cells.3
When you apply glycolic acid to your skin, it also boosts your skin's collagen production. This protein helps plump the skin and give it a firm yet elastic feel. As a result, glycolic acid can help strengthen the skin and prevent collagen breakdown that causes fine lines.2

Benefits of Glycolic Acid
"Any skin type can benefit from using glycolic acid, including oily, dry, and combo skin," Gabriella Vasile, DO, FAAD, a board-certified dermatologist and founder of Réforme Dermatology & Aesthetics in Charleston, told Health. "Glycolic acid promotes cell turnover and collagen formation, so your skin will appear brighter, smoother, and clearer."
The versatile skin benefits of glycolic acid include: 

Smooths Fine Lines
As you age, your skin loses collagen that helps the skin feel elastic and plump. This loss in collagen eventually leads to fine lines and wrinkles. Glycolic acid can help reduce these signs of aging by stimulating collagen production, Anna Chacon, MD, a board-certified dermatologist in Miami, told Health. 
Glycolic acid's exfoliating effect also helps improve skin tone and texture as you age.2 Additionally, glycolic acid increases your skin's hyaluronic acid levels.4 Hyaluronic acid helps your skin retain moisture and stay hydrated. It also helps plump the skin to reduce the look of fine lines.5 

Fades Dark Patches and Sun Damage
Dermatologists often recommend glycolic acid to fade dark patches of skin (hyperpigmentation) caused by acne or sun damage. It is also safe to use on darker skin tones.6 Glycolic acid helps fade dark spots by exfoliating the top skin layer and brightening the skin.2
Research shows glycolic acid can also help protect your skin's collagen from the sun, which may help prevent future sun damage.4

Clears Pores and Helps Treat Acne
"For those with oily and acne-prone skin, glycolic acid can help reduce oil production and unclog pores, preventing acne breakouts," said Chacon. If you have a breakout, you're dealing with pores clogged with oil, dirt, or skin cells. When glycolic acid exfoliates the skin, it sloughs away dead skin cells and unclogs pores. Glycolic acid also helps reduce excess oil, which can help prevent acne.7 

Because glycolic acid helps dissolve dead skin cells, it can also help prevent ingrown hairs stuck inside skin cell buildup. Additionally, glycolic acid can help treat strawberry skin (keratosis pilaris). If you have these small red bumps caused by plugs of dead skin cells, glycolic acid can smooth rough skin and remove dead skin cells from pores.8

How to Use Glycolic Acid
When using any new OTC glycolic acid product, always follow the directions. Since glycolic acid makes your skin sun sensitive, it's best to use glycolic acid products at night and a SPF in the morning.1

How often you use glycolic acid will also depend on the product. Vasile suggests adding only one form of glycolic acid to your routine. Here's how Chacon recommends adding glycolic acid products to your skincare routine:
Cleansers: Use a pea-sized amount once or twice daily, depending on your skin sensitivity. However, using these cleansers at night is generally advised due to sun sensitivity. 
Toners, serums, or creams: The amount of leave-on product will vary, but you can typically use a few drops of serum or a pea-sized amount of cream once daily. Preferably, you should only apply in the evening.
Glycolic acid peels: Use these products less frequently because they are more concentrated. Depending on the concentration and your skin's tolerance, you can use a peel once a week or every two weeks.
"Regardless of the product type, it's important to start slow when introducing glycolic acid into your routine, gradually increasing frequency as your skin adjusts," said Chacon. Vasile recommends using glycolic acid products one to two times a week to start, then gradually building up to three times a week. 

Side Effects of Glycolic Acid
Glycolic acid can irritate the skin, so people with extremely sensitive skin should use glycolic acid with caution, noted Chacon. People with sensitive, dry skin may have better results with lactic acid, a gentler AHA.2 Since glycolic acid can be irritating, Vasile recommends following up with a moisturizer to help rehydrate the skin barrier.
Glycolic acid also makes skin super sensitive to the sun and increases your risk of sunburn.1 During the day, always apply a board-spectrum sunscreen with a sun protection factor (SPF) of at least 30 to protect your skin.9

Other potential side effects of glycolic acid include:1

Skin rash
Skin swelling
Blisters or welts 
Skin peeling 
Skin irritation or tenderness
Chemical burns
More severe side effects are more likely if you use a glycolic acid peel with more exfoliating power.1 Vasile also notes that pregnant people can safely use glycolic acid in concentrations under 10%.10

Can You Use Glycolic Acid With Retinol?
You can use glycolic acid with retinol, but you want to avoid mixing them directly because they can both irritate the skin. Instead, Vasile recommends alternating the nights when you use glycolic acid and retinol.
Retinol is a type of retinoid that works similarly to glycolic acid by increasing cell turnover and boosting collagen production. It's a lot more potent if you use a prescription-strength retinoid. Since they have similar effects on the skin, mixing glycolic acid with retinol together can be irritating.11 Still, there are benefits to using both if you have oily, acne-prone skin. A small 2015 study found participants who use retinol and glycolic acid products decreased their need for additional acne scar treatments.12

Before adding glycolic acid to your routine, make sure your skin has adjusted to retinol. Start using retinol once a week to see how your skin reacts, then gradually add it a few times a week. After a few months, if your skin is still doing well, use a glycolic acid product on days when you don't use retinol. Eventually, you can alternate using each product at night.11