Everything You Need to Know About Acid Serums

Different types of acid serums

I used to be a bit of a wimp when it comes to skincare. Convinced that my skin was hopelessly dry, I’d use only the gentlest face washes, followed by generous layers of organic oils. If my skin got flaky, I might use a physical exfoliant or resurfacing mask—Origins’ Original Skin Retexturizing Mask With Rose Clay ($27) is still my fave. For breakouts, I’d apply an all-natural spot treatment (or not even treat my blemishes at all). Like I said, I was a bit of a wimp.

Chemical exfoliators were definitely not in my routine. I didn’t mess with acids. Even the names of the ingredients were harsh and intimidating. (Doesn’t the word jojoba sound so much friendlier than glycolic?) Frankly, I was a little afraid of them.

I realize now that my fear was rooted in one thing, and that was a lack of information. Not long ago, I visited celebrity esthetician Renée Rouleau, who completely overhauled my skincare regimen. One of the major changes she suggested was introducing an acid serum into my nighttime routine. Renée’s Ultra Gentle Smoothing Serum ($48) with a 10 percent glycolic acid concentration is specifically formulated for sensitive skin types and people new to acid serums. She promised the product would help my skin stay clear, radiant, and wrinkle-free without irritation. I can already say with confidence that, after less than a month of use, my skin has never looked better.

I’m now an acid serum convert, and I want to spread the word. But there are so many different types and concentrations out there that figuring out which one to use can be daunting. So, I asked Rouleau the tough questions to help you find the best acid serum for your skin. And trust me, there’s an acid for everyone.

Curious about acid serums? Skeptical about putting chemicals on your face? To get the scoop on this essential (and totally un-scary) part of your skincare routine, keep scrolling.

Let’s start with the basics. According to Rouleau, the acids found in serums (as well as toners, cleansers, and other treatments) are ingredients that work to lower the pH of the skin. This process “chemically dissolves and digests the glue that holds cells together, encouraging the removal of dry surface cells,” she says. Removing this cell buildup makes way for newer, healthier cells that reflect light, allowing you to exude that lit-from-within glow.

What Is an Acid Serum?

Common acids in at-home skincare products include exfoliators like glycolic, lactic, and salicylic acids. Rouleau says these have been skincare staples for years, thanks to their clinical effectiveness treating a wide variety of skin conditions, from breakouts to discoloration.

The Benefits of Acid Serums

I always thought acid serums were helpful only to people with severe acne or deep wrinkles. But the scope of skin concerns they treat is much larger. “Acid serums can help skin appear smoother, reduce clogged pores and breakouts, increase collagen production, even out skin tone, soften fine lines, reduce hyperpigmentation, and eliminate dryness and flakiness,” says Rouleau. The argument for serums specifically, as opposed to acid cleansers, for example, is that they're easy to add into your existing routine and get left on the skin long enough to work their real magic. In short, odds are you can benefit from these products in some capacity.

That said, you want to make sure you use an acid that’s appropriate for your skin type. For example, Rouleau’s AHA Smoothing Serum, which I use now, comes in three different concentrations—10 percent, 17 percent, and 20 percent. I use the lowest percentage, but another skin type might benefit from a higher one. (If you’re at all unsure of your skin type, Rouleau’s super-insightful diagnostic quiz can help you figure it out.)

“Often people gravitate toward the stronger percentage thinking it will give them better and faster results,” says Rouleau, “But it’s definitely possible to cause sensitivity if it’s more than your skin can handle.”

Do Acid Serums Work on All Skin Types?

Speaking of what your skin can handle, Rouleau says the most common misconception people have about acid serums is that they are too sensitive for them. (Ahem, guilty.) “But it’s very rare that someone can’t use any products with acid in them at all, especially if they are using the products as directed,” says Rouleau.

In other words, just as not all carbs are created equal (you have your simple sugars, your whole grains, your starches, fruits, etc.), acid serums have their differences. So you can’t expect the same results from every last one. If you’re truly concerned, Rouleau suggests patch-testing the product on a small area of your face before applying it all over. “Once you feel confident that your skin won’t react negatively, start using [the serum] one night a week for the first three weeks, and then gradually move up to three nights, but no more than that,” Rouleau recommends.

How to Choose the Right Acid Serum

To help you find the perfect acid serum for your skin type, here’s a quick rundown. We’ve listed the types of acids most commonly found in serums, as well as the skin conditions they treat, and some product recommendations.

Citric Acid: A fruit-derived alpha-hydroxy acid, this ingredient helps stimulate collagen fiber production and correct skin discoloration. Try Drunk Elephant's T.L.C. Framboos Glycolic Resurfacing Night Serum ($90).

Glycolic Acid: Derived from sugar cane, this AHA exfoliates, hydrates, and rejuvenates the skin, helping to smooth fines lines and wrinkles. It’s considered one of the most effective anti-aging ingredients by many skincare professionals. Try Renée Rouleau's Ultra Gentle Smoothing Serum ($48).

Lactic Acid: A milk-derived AHA, this ingredient also exfoliates and hydrates skin, working to diminish fine lines and wrinkles. Try Sunday Riley's Good Genes All-in-One Lactic Acid Treatment ($122).

Salicylic Acid: This beta-hydroxy acid is most commonly used to clear acne and blemish-prone skin.

Tartaric Acid: Derived from wine, this acid helps even out skin texture and tone. Try Renee Rouleau Triple Berry Smoothing Peel ($88).

Malic Acid: Another fruit-derived AHA, this ingredient helps increase oxygen supply, which reduces inflammation and stimulates collagen production.

How to Use an Acid Serum

Apply your acid serum before bed—never as a part of your morning routine. “It has been shown that using exfoliants regularly increases sun sensitivity by 45 percent,” says Rouleau. “Acids that are left on the skin for extended periods of time, like serums, should only be used at night.” You’ll also get better results this way, as your skin goes into repair mode while you sleep. “Acidic ingredients encourage and aid in that skin repair,” says Rouleau.

Also, remember that applying your acid serum every single night can have negative effects. Instead, use it this way: After cleansing and toning, apply a thin coat all over the face, then follow up with your favorite night cream. “Use for three nights on, three nights off,” says Rouleau. Using your acid serum three nights in a row allows the ingredients to exfoliate the skin a little deeper each time. After those three nights, you want to expose your new, fresh cells to nourishing ingredients like hydrators, brighteners, and skin-calming antioxidants. Try Kate Somerville's Quench Hydrating Face Serum ($75) or SkinCeuticals's Phloretin CF ($166).

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