Why You Should Add Glycolic Acid to Your Nighttime Routine

As someone with skin that’s both dry and sensitive, I tend to stay away from harsh skincare ingredients or treatments.

I have friends who love getting face peels or slathering tons of exfoliators and more intense ingredients on their faces, but I typically steer clear. 

While I pride myself on typically smooth, clear skin, I’ve noticed more dullness and fine lines recently. Since I’m in the process of revamping my nighttime skincare routine, I want to make sure I’m incorporating every single product I possibly can for the ultimate beauty sleep (pun most definitely intended)—and I’m currently extremely intrigued by glycolic acid.

That’s why I turned to Hadley King, MD, a board-certified dermatologist in New York City, for the 411 on what glycolic acid is, its benefits for the skin, and how to safely include it in an evening skincare routine. 

Keep reading for everything you need to know about glycolic acid and how to safely use it while you get your Z’s.

What is glycolic acid?

Simply put, glycolic acid is an alpha hydroxy acid (aka an AHA) derived from sugarcane.

“It is the smallest AHA, which allows it to penetrate the skin effectively,” says King. “It works primarily by loosening the bonds between dead skin cells at the surface, helping them shed more evenly.”

Why nighttime is the best time to use glycolic acid

While King notes that it’s not imperative for someone to use glycolic acid solely at night, it’s also often the way to go.

“It minimizes exposure to environmental factors while it’s on the skin, and makes it easier to keep the morning routine focused on antioxidant protection, moisturizer, and sunscreen,” she explains. “For most people, nighttime is simply the easiest and most practical time to incorporate it.”

However, whether you use glycolic acid during your daytime or evening skincare routines, you still need to be diligent about applying sunscreen. (And, let’s be honest, you should be applying that every day as it is.)

This is because glycolic acid can make your skin “more vulnerable to damage from UV exposure,” says King.

Top benefits of glycolic acid for your skin

So, what are the exact skincare benefits of glycolic acid, anyway?

“Because it exfoliates and can penetrate relatively well, glycolic acid can improve both the appearance and feel of the skin,” says King.

Here are the most important benefits of glycolic acid for your skin.

Smooths rough texture and uneven tone

“Glycolic acid helps remove accumulated dead skin cells, resulting in smoother, softer skin,” says King.

She also advises using it consistently, which can help fade the appearance of discoloration and help skin look more even over time.

And here’s the best part: King says you don’t have to restrict glycolic acid to your face.

“Glycolic acid is also excellent for areas like the arms, legs, and décolletage, where there may be roughness, keratosis pilaris, or uneven texture,” she says.

Unclogs pores and prevents breakouts

Let’s face it (again, pun most definitely intended)—clogged pores and breakouts are a nuisance and a half. Thankfully, glycolic acid helps keep both of those pesky skincare issues at bay.

“By promoting exfoliation, glycolic acid can help prevent dead skin cells from accumulating around pores,” explains King.

However, she also cautions against using glycolic acid as the one-and-done skincare ingredient when it comes to unclogging pores.

Instead, she points to salicylic acid, since it’s oil-soluble and penetrates more deeply into the pores.

But she still recommends glycolic acid for acne-prone skin, “particularly when rough texture and post-inflammatory discoloration are concerns,” she says.

Boosts natural skin glow

Searching for the ingredient to give your skin a more luminous, lit-from-within glow? Glycolic acid may just be the answer.

Since it works to remove excess surface cells, it helps light reflect more evenly, so “it can give the complexion a brighter, more luminous appearance,” King explains.

How to safely add glycolic acid to your nighttime routine

Now that you know a little more about what glycolic acid is, it’s time to put it to work. Follow this step-by-step evening skincare routine recommended by Dr. King.

Step 1: Cleanse with a gentle cleanser, being careful not to scrub the skin. “Pat the skin dry and allow it to become completely dry if you’re prone to irritation,” King advises.

Step 2: Apply a thin layer of your preferred glycolic acid product. “Apply the glycolic toner, serum, or treatment according to the product’s directions,” says King. “You don’t need to layer multiple glycolic products.”

Step 3: Follow with a bland, barrier-supportive moisturizer. King suggests looking for ingredients like ceramides, glycerin, squalane, or hyaluronic acid.

Step 4: In the morning, use broad-spectrum SPF 30 or higher (“and every morning,” King says emphatically). 

Hot tip: “I generally recommend beginning with a relatively low-strength product, often around five to seven percent for a leave-on product,” says King.

Additionally, begin by incorporating it into your nighttime routine only once or twice a week, so you can be sure it doesn’t irritate your skin.

“If the skin is tolerating it well after several weeks, frequency can gradually be increased,” King says, though she cautions that “more is not necessarily better with exfoliating acids.”

Common mistakes to avoid with glycolic acid

When it comes to the pitfalls of using glycolic acid, King says there’s one common mistake that rises above the rest.

“The biggest mistake is over-exfoliating,” she says. “People sometimes assume that if a little glycolic acid makes their skin smoother, using it every night or combining it with several other exfoliating products will produce even better results.”

In fact, doing this can actually produce the opposite effect, causing rougher and more irritated skin. Less is most definitely more.

Additionally, King has a few other common mistakes to look out for when using glycolic acid in your evening skincare routine:

• Starting with too high a concentration of the product
• Using glycolic acid too frequently
• Applying glycolic acid to already irritated, sunburned, or compromised skin
• Combining it immediately with multiple potentially irritating actives—think retinoids, other AHAs and BHAs, or strong acne treatments
• Neglecting moisturizer
• Assuming that a tingling or burning sensation means the product is “working better”
• Skipping sunscreen, which King says is “especially important when using an exfoliating acid”
• And, finally, using glycolic acid if it’s not right for your skin. “Using glycolic acid simply because it’s trendy when another ingredient may be better suited to the concern” is something King says you should avoid.

FAQs

Can you use glycolic acid every night?

In short? You can, although it’s actually not necessary—or, in most cases, even preferred. King cautions against using glycolic acid too often as it can actually be too harsh for your skin and cause roughness, dryness, and irritation.

Instead, start by applying it only once or twice a week to see how it works with your skin type, and then you can subtly increase from there.

“Initially, give the skin non-acid nights between applications,” she says. “Once someone knows their skin tolerates glycolic acid well, they can determine whether they actually need to increase frequency.”

Should you put moisturizer on after glycolic acid?

Absolutely. Since glycolic acid works to exfoliate the skin and sweep away dead skin cells, it can also strip the skin barrier of its nutritive oils.

Be sure to apply a barrier-supporting moisturizer after your glycolic acid product, and look for ingredients like ceramides, hyaluronic acid, glycerin, or squalane to help nourish and hydrate the skin.

Does glycolic acid help with dark spots?

The good news is, glycolic acid may be able to help fade dark spots, otherwise known as hyperpigmentation.

“Glycolic acid can accelerate the turnover of pigmented surface cells,” King says. “Over time, it can improve the appearance of sun spots and post-inflammatory hyperpigmentation.”