Because all acids are great, but not all are created equal.

By Melanie Rud
April 14, 2021
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There's arguably no category of skincare ingredients that can do more than direct acids. They're well-known—and beloved—for their ability to do everything from brighten skin to unclog pores. But, while there is some overlap among all of the many different types of acids out there, they're by no means all the same. Some have very unique benefits, and they all have distinct features that make them better suited for certain skin types and/or complexion concerns. Ahead, top dermatologists weigh in on everything there is to know about 11 of the most common acids out there (consider it your ultimate guide to direct acids).

Ascorbic Acid

What it is: Also known as l-ascorbic acid, this is the most potent form of topical vitamin C, naturally occurring in a variety of fruits and vegetables, though also often synthesized in a lab.

What it can do for your skin: In short, a lot. First and foremost, it’s an extremely potent antioxidant that helps to protect skin from free radicals formed by exposure to environmental factors such as pollution and UV rays, explains Marie Hayag, MD, a board-certified dermatologist in New York City and founder of Fifth Avenue Aesthetics. Topical application of vitamin C has also been shown to play a key role in the production of collagen, the protein responsible for keeping skin strong and youthful, she adds. And finally, it’s effective at inhibiting the production of melanin, or pigment, a great pick for those who want to fade dark spots and discoloration.

Try it if: According to Dr. Hayag, ascorbic acid’s powerful antioxidant properties make it a great choice for pretty much anyone and everyone, a universal crowd pleaser. Just FYI, don’t use it at the same time as any retinoids in your skincare routine, as the two work at different pH levels and can ultimately inactivate one another.

Find it in: Drunk Elephant C-Firma Day Serum ($80; sephora.com). Apply this ascorbic acid-rich serum under your sunscreen every morning for an added layer of protection.

Azelaic Acid

What it is: An ingredient naturally found in grains, including barley, rye, and wheat, and that’s also produced by yeast on your own skin.

What it can do for your skin: It’s ideal for treating both comedonal acne—blackheads and whiteheads—as well as inflammatory acne, says Dr. Hayag, thanks to its antimicrobial properties. As an added benefit, it combats hyperpigmentation too, by preventing discolored cells from developing, says Debra Jaliman, MD, board-certified dermatologist and assistant professor of dermatology at Icahn School of Medicine at Mount Sinai in New York City. And that’s a major win when it comes to stopping and treating the discoloration often associated with acne scarring.

Try it if: All skin types can benefit from using it, but it’s especially great for those prone to acne and hyperpigmentation. Fun fact: It’s also one of the few acne-fighting ingredients that women can use during pregnancy, notes Dr. Jaliman.

Find it in: Paula’s Choice 10% Azelaic Acid Booster ($36; sephora.com) combines azelaic with another super powerful acne-fighting acid, salicylic acid, more on that ingredient to come.

Citric Acid

What it is: As the name suggests, it’s an acid that comes from citrus fruits, oftentimes lemon. It belongs to a class of acids known as alpha hydroxy acids, lauded for being great chemical exfoliants that work on the surface of the skin to improve tone and texture.

What it can do for your skin: Along with these exfoliating benefits, citric acid also has antioxidant properties, says Dr. Hayag.

Try it if: You’re going to be using it in lower concentrations and/or you don't have sensitive skin. “Citric acid can be irritating, especially in concentrations over 10%, due to its acidic pH,” points out Dr. Hayag. She adds that it’s also not as well-studied as its more often-recommended counterparts, glycolic and lactic acids. (More info on those in a moment.)

Find it in: Neostrata Perfecting Peel ($85; dermstore.com). A favorite of Dr. Jaliman’s, she says these pads, which combine citric and glycolic acids, are a good option to use weekly to improve skin’s clarity and brightness.

Glycolic Acid

What it is: Arguably one of the more popular acids out there, glycolic acid is an alpha-hydroxy acid derived from sugarcane. The smallest of the AHAs, it’s the one that’s able to penetrate the deepest and as such the most effective, though also does have the highest potential of causing irritation.

What it can do for your skin: A great exfoliator, it’s perfect for brightening up the skin and combating discoloration, leaving it looking overall glowy and refreshed, while also improving the texture to make it appear smoother, says Dr. Jaliman. Glycolic acid is also unique in that it works on the deeper layers of the skin where it can stimulate collagen production, adds Dr. Hayag. Translation? Fewer wrinkles.

Try it if: You’re looking for some anti-aging benefits, and/or if your skin isn’t very easily-irritated.  

Find it in: La Roche-Posay Glycolic Acid B5 Dark Spot Corrector ($32; ulta.com). Yes, this helps combat dark spots, but it also generally improves the tone and texture of your skin, leaving it smoother and more even.

Ferulic Acid

What it is: This isn’t an ‘acid’ in the traditional sense; rather, it’s a powerful antioxidant that’s naturally found in many types of fruits and grains.  

What it can do for your skin: Along with being a powerful antioxidant that protects skin from damaging free radicals, it also has anti-inflammatory properties, says Dr. Hayag.

Try it if: Dr. Jaliman says its powerful antioxidant properties makes it a great choice for all skin types. You’ll usually see it formulated in conjunction with vitamin C and vitamin E because it increases their stability, explains Dr. Hayag, ultimately upping the antioxidant prowess.

Find it in: SkinCeuticals C E Ferulic ($166; dermstore.com). Another one of Dr. Jaliman’s picks, this does in fact have that unique trifecta of antioxidants, making this formula super potent and effective.  

Hyaluronic Acid

What it is: Again, this isn’t like other acids. It’s actually a sugar that’s naturally found in our own bodies (it’s made in a lab for use in topical skincare). It’s a humectant, meaning it draws water to and traps it in the skin.

What it can do for your skin: Because it’s a humectant, it’s one of the best hydrating ingredients out there, able to bind 1000 times its own weight in water, says Dr. Hayag. Not only does this quickly combat dehydration, it can actually help improve the look of wrinkles, too, instantly plumping up skin and making it appear smoother.

Try it if: Hyaluronic acid is also very well-tolerated, an ingredient that pretty much anyone and everyone can use. It’s great if your skin is dry, but really anyone could—and should—consider using it.

Find it in: L’Oréal Paris Revitalift Derm Intensives Hyaluronic Acid Facial Serum ($24; target.com). Layer it under a thicker moisturizer if you have super dry skin, or try using it on its own if your skin is oilier or more acne-prone.

Lactic Acid

What it is: Another alpha hydroxy acid, this comes from milk.

What it can do for your skin: Again, those same exfoliating benefits of all of the other AHAs we’ve talked about apply here as well.  It’s also a humectant, meaning it can attract water to the skin, so it’s less drying than some other exfoliating acids.

Try it if: You want to reap the benefits of alpha hydroxy acids, but are looking for something that’s potentially less intense and irritating than glycolic acid; because lactic acid is a larger molecule, it can’t penetrate as deeply and is less likely to cause unwanted irritation.

Find it in: Sunday Riley Good Genes All-In-One Lactic Acid Treatment ($85; sephora.com) can be used as an overnight leave-on serum, or as a 15-minute, rinse-off mask if you have super sensitive skin.

Mandelic Acid

What it is: An alpha hydroxy acid derived from bitter almonds.

What it can do for your skin: Its use in dermatology isn’t very well-studied, notes Dr. Hayag, though it does effectively exfoliate and can help improve the texture of your skin.

Try it if: “Mandelic acid has larger-sized molecules than other alpha hydroxy acids, which means it penetrates the skin more slowly. As such, it’s gentler on the skin than the other AHAs,” says Dr. Jaliman. Try it if you want to reap the benefits of an AHA—specifically improved tone and texture—but without the irritation.

Find it in: The Ordinary Mandelic Acid 10% + HA ($7; ulta.com), a gentle and affordable recommendation from Dr. Jaliman.   

Oleic Acid

What it is: Another “non-acid,” this is actually a fatty acid found in various plants, including olives and sea buckthorn, says Dr. Hayag. It’s also a natural component of many oils often used in skincare, including sunflower and olive oils.

What it can do for your skin: Nourishes and moisturizes, though it’s best when combined with other ingredients, such as other fatty acids, to ultimately yield the most effective results.

Try it if: You have dry, mature skin and need a lot of moisture. Anyone with acne-prone skin should avoid oleic acid, and the oils that are rich in it, because it can be comedogenic, warns Dr. Hayag.  

Find it in: Biossance Squalane + Omega Repair Cream ($58; sephora.com), which combines oleic acid with other skin-loving omega fatty acids.

Salicylic Acid

What it is: The most commonly used beta hydroxy acid, this is derived from willow tree bark, says Dr. Hayag.

What it can do for your skin: Unlike AHAs, which are water soluble, BHAs are oil-soluble. Why does that matter? “It means they can get deeper into the pores to dissolve excess sebum,” says Dr. Jaliman, as well as help remove dead skin cells and unclog pores and help ease inflammation, too.

Try it if: Salicylic acid is ideal for those with oily or acne-prone skin. Reach for the ingredient if you’re looking to help target whiteheads, blackheads, or clogged pores, advises Dr. Hayag

Find it in: No7 Laboratories Acne Treatment 2% Salicylic Acid ($23; ulta.com). A 2% concentration of salicylic acid is paired with kaolin clay to help purify skin and minimize blemishes, as fast as overnight.

Tartaric Acid

What it is: Naturally found in grapes, tartaric acid is another alpha hydroxy acid.

What it can do for your skin: Like the others AHAs, it does exfoliate, though Dr. Hayag notes that in skincare products it’s often used more to regulate the pH so that other AHAs it’s formulated with function optimally.

Try it if: That being said, because it does have a larger molecular size, it’s another good option that’s less likely to be irritating, and is more suitable for those with sensitive skin, says Dr. Hayag.

Find it in: Juice Beauty Prebiotix Instant Flash Facial ($52; dermstore.com) works in just one to two minutes, thanks to a blend of exfoliating tartaric and glycolic acids.