Chemical exfoliation is one of the best things you can do to slough away dead skin and reveal a healthy, youthful glow. Whether it’s an in-office chemical peel or an at-home serum, skincare acids can help treat many skin concerns—but not all skincare acids are created equal.
The amount of various kinds of acids in skincare products is daunting, and it’s difficult to know which one does what and which acid is ideal for your skin concern. Below, we’ve consulted with the pros to figure out what each face acid is, what it's used for, which skin concerns it treats, and when you should be cautious with usage.
1. Lactic Acid
What is lactic acid?
Lactic acid is derived from milk or other alternative vegan sources and is a hydrating, gentle alpha-hydroxy acid (AHA). “AHAs work by breaking down the 'glue' that holds the dead skin cells together so that it can act as a chemical exfoliant,” explains Emmy Graber, M.D., a board-certified dermatologist and president of The Dermatology Institute of Boston.
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Which skin types should use lactic acid?
If you are someone who struggles with aging, dry skin, or uneven skin tone, lactic acid is the AHA for you. It’s one of the more gentle AHAs and won’t cause much (if any) irritation.
Benefits of lactic acid:
Lactic acid is most commonly used for treating hyperpigmentation, age spots, fine lines and wrinkles, and an overall dull complexion.
Potential side effects of lactic acid:
Although it may help with mild acne, Dr. Graber does not recommend using any AHAs if you suffer from eczema.
2. Salicylic Acid
What is salicylic acid?
Salicylic acid is derived from willow bark and is a “beta-hydroxy acid (BHA)," says Dr. Graber. "It works similarly to AHAs, but salicylic acid can also penetrate the pilosebaceous unit (aka the pore) and help to exfoliate dead skin cells from deeper within the pore. Because of this, salicylic acid is particularly helpful for acne.”
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Which skin types should use salicylic acid?
If you’re suffering oily skin or breakouts, salicylic acid is your best bet. Salicylic acid can reach deep into the skin to dissolve skin debris that’s clogging pores and causing you to break out.
Benefits of salicylic acid:
Since salicylic acid gently exfoliates surface-level bacteria and penetrates the pores to clean out bacteria, it's very effective in treating and preventing acne as well as evening out skin texture.
Potential side effects of salicylic acid:
Salicylic acid is great for busting breakouts, but it can be rough on those with sensitive skin as it can often be drying. If you are someone with sensitive, acne-prone skin, use salicylic acid with caution and always apply moisturizer over the salicylic acid once it’s dried.
3. Ferulic Acid
What is ferulic acid?
Ferulic acid is a popular antioxidant, and in skincare formulations it's often found alongside vitamin C in a serum form.
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Which skin types should use ferulic acid?
According to Deanne Robinson, M.D., a board-certified dermatologist and assistant clinical professor of dermatology at Yale New Haven Hospital in Connecticut, all skin types can benefit from ferulic acid's protective qualities against free radical damage. With continued use, ferulic acid can improve signs of premature aging and reduce the appearance of wrinkles, too.
Benefits of ferulic acid:
“Ferulic acid helps to stabilize vitamin C, making it more shelf-stable and protecting its potency,” explains Dr. Robinson. “Research also shows that, when paired with vitamin C, ferulic acid can boost photoprotection from the sun and blue light.”
Potential side effects of ferulic acid:
Dr. Robinson says to avoid layering ferulic acid with other AHA and BHA exfoliating acids, which can alter the skin’s pH levels and interfere with the effectiveness of an antioxidant serum.
4. Kojic Acid
What is kojic acid?
Kojic acid is another AHA that has exfoliating benefits, but it’s best known for its ability to lighten hyperpigmentation. “Kojic acid suppresses tyrosine—the enzyme that helps our bodies to produce melanin—and has anti-fungal and antibacterial benefits,” explains Dr. Robinson.
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Which skin types should use kojic acid?
Anyone with visible sun damage (solar lentigines), melasma, and/or hyperpigmented acne scarring can benefit from kojic acid. “Plus, if you use [kojic acid] alongside other exfoliating AHAs (like glycolic acid), you will see an incremental benefit,” says Dr. Robinson.
Benefits of kojic acid:
It helps to lighten dark spots, so anyone with uneven skin tones can benefit from using a kojic acid-infused skincare product.
Potential side effects of kojic acid:
Kojic acid could lead to contact dermatitis for those with super sensitive skin. Otherwise, it’s pretty safe to use on all skin types.
5. Hyaluronic Acid
What is hyaluronic acid?
Hyaluronic acid is a hero hydrating ingredient that acts as a humectant moisturizer. It can be found in our skin naturally, and Dr. Graber explains that it helps with moisture retention since it holds up to 1,000 times its weight in water.
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Which skin types should use hyaluronic acid?
Hyaluronic acid is ideal for those with dry, dehydrated skin, but it works nicely on all skin types. Additionally, it's the perfect hydrator for those with oily skin, as it offers a more lightweight texture than other oils or emollients you might find for dry and dehydrated skin.
Benefits of hyaluronic acid:
Hyaluronic acid-based creams and serums help replenish the skin's moisture levels, making it a great ingredient for combating dryness.
Potential side effects of hyaluronic acid:
There’s currently debate on whether hyaluronic acid molecules are too big to penetrate the skin. When applied topically, hyaluronic acid can sit on the skin and provide moisturizing properties, but some formulas may not actually penetrate the skin and provide the moisturizing and anti-aging benefits that many skincare brands claim.
6. Citric Acid
What is citric acid?
Extracted from citrus fruits, citric acid is an AHA that helps to exfoliate the skin and get rid of dead skin cells.
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Which skin types should use citric acid?
“Those looking to brighten the skin [and] improve discoloration and dullness can benefit,” says Marisa Garshick, M.D., a board-certified dermatologist at Manhattan’s Medical Dermatology & Cosmetic Surgery.
Benefits of citric acid:
“By stimulating new skin cells, it can also help improve the appearance of fine lines and wrinkles,” explains Dr. Garshick. When used in certain concentrations, citric acid is a great option for those who are looking for the benefits of an exfoliant but are unable to tolerate some of the stronger acids.
Potential side effects of citric acid:
Along with many exfoliants, those with sensitive skin should use caution when using products containing citric acid. “As with other AHA’s, you should avoid use at the same time as retinol, as the two together can be irritating,” explains Dr. Garshick. “That being said, it can complement many other active ingredients in a skincare routine.”
7. Ascorbic Acid
What is ascorbic acid?
According to Dr. Graber, ascorbic acid (also known as L-ascorbic acid) is a form of vitamin C that has been proven to prevent some cellular damage when the skin is in UV light. Ascorbic acid works as a potent antioxidant to help protect the skin and repair sun damage.
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Which skin types should use ascorbic acid?
All skin types can use ascorbic acid, but people with uneven skin tones will benefit from it the most.
Benefits of ascorbic acid:
Because of its high acidity, ascorbic acid triggers the skin to heal itself by accelerating elastin and collagen production, making the skin look firmer. Additionally, this ingredient can inhibit your skin’s melanin production (an overproduction of melanin can cause dark spots and hyperpigmentation). With continued use, ascorbic acid can prevent hyperpigmentation from occurring, so if you’re someone who suffers from uneven skin tone and wants to lighten pre-existing brown spots, definitely give ascorbic acid a try.
Potential side effects of ascorbic acid:
If you have sensitive skin, you should either avoid ascorbic acid or use it in a lower dosage. Another con of ascorbic acid is that it can oxidize quickly when exposed to light and air, so it’s important to find a vitamin C product that comes in a dark bottle and to use your ascorbic acid-based product within three months for best results. Additionally, it’s advised not to use vitamin C with retinol, as vitamin C requires a low pH level for skin absorption, while retinol requires a higher pH level. When you mix the two, it might render each ingredient ineffective.
8. Malic Acid
What is malic acid?
Malic acid is a mild AHA that's often used in conjunction with other exfoliants to help brighten the skin, improve dark spots, and even out texture.
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Which skin types should use malic acid?
“It can be used by most skin types, but because it’s not as strong as some other AHAs (given its larger molecule size and not being able to penetrate as deeply) it is often combined with other [acids] to give the most benefit,” explains Dr. Garshick.
Benefits of malic acid:
Malic acid helps to eliminate dead skin cells, improving the overall appearance of the skin. “Additionally, malic acid is also a humectant (like hyaluronic acid), meaning it helps to draw moisture in and helps the skin retain moisture,” explains Dr. Garshick.
Potential side effects of malic acid:
Although it is often tolerated even by those with sensitive skin, given that it is an AHA it can be irritating; those with sensitive skin should still use it with caution. In general, as with all AHAs, it is important to use caution with other harsh active ingredients such as retinol.
9. Azelaic Acid
What is azelaic acid?
Azelaic acid is a dicarboxylic acid derived from grains (such as barley and wheat) and acts as both an exfoliant and antioxidant.
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Which skin types should use azelaic acid?
People with uneven skin texture, acne, and rosacea can benefit from using skincare products with azelaic acid.
Benefits of azelaic acid:
“Azelaic acid can be used to soothe skin and for improving the bumps of acne or rosacea, and it can also help to improve uneven skin tone,” says Dr. Graber. “It is available over the counter in strengths 10% and less and as a prescription in strengths 15% and 20%.”
Potential side effects of azelaic acid:
For those with sensitive skin, azelaic acid should be used in lower doses as it can sometimes be irritating.
10. Oleic Acid
What is oleic acid?
“Oleic acid refers to an omega-9 fatty acid found naturally in the skin," explains Dr. Garshick. "It can nourish and hydrate the skin.”
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Which skin types should use oleic acid?
According to Dr. Garshick, dry skin types can benefit from plant oils that are rich in oleic acid. “That said, high-concentration oleic acid products can be irritating to the skin, increase inflammation, and worsen flaking, especially in those with eczema,” she says.
Benefits of oleic acid:
Studies show that oleic acid has anti-inflammatory benefits and that it can help repair a damaged skin barrier caused by things like sunburns and over-exfoliation.
Potential side effects of oleic acid:
“In general, oleic acid can be formulated with other ingredients, but because in high concentrations it can disrupt the skin barrier and enhance penetration, it is best to avoid it in combination with other ingredients that can be harsh on the skin,” explains Dr. Garshick. “If looking for products with oleic acid, it is best to look for products containing certain types of oils that contain a higher percentage of oleic acid, such as sunflower oil, argan oil, marula oil, or olive oil.”
11. Glycolic Acid
What is glycolic acid?
Derived from sugarcane, glycolic acid is another AHA that works by loosening up the “glue” that holds the dead skin cells together.
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Which skin types should use glycolic acid?
Most skin types can benefit from using glycolic acid, but sensitive skin types should ease into it by using it twice a week to prevent further sensitizing the skin.
Benefits of glycolic acid:
Glycolic acid is a powerhouse AHA that can treat multiple skin concerns, including fine lines and wrinkles, enlarged pores, acne, and uneven skin tone. Plus, it can also help stimulate new skin cell regeneration, resulting in a brighter, more even complexion.
Potential side effects of glycolic acid:
Dr. Graber doesn't recommend glycolic acid to people with eczema since it can cause a reaction. Those with normal to oily skin shouldn’t have an issue with glycolic acid, but if you have sensitive skin, choose a product with a low percentage of glycolic acid.
12. Mandelic Acid
What is mandelic acid?
Mandelic acid is an exfoliating AHA that helps to increase skin cell turnover.
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Which skin types should use mandelic acid?
“Mandelic acid can be beneficial for anti-aging and acnegenic skin, including papulopustular rosacea,” says Dr. Robinson. “It is gentler than most other AHAs and well tolerated by sensitive skin types.” Dr. Robinson recommends this to her patients in their 20s through 40s who are simultaneously battling hormonal acne and the signs of aging.
Benefits of mandelic acid:
Since mandelic acid helps increase skin cell turnover, it also helps to boost the skin's natural glow and brightens the face. Plus, it helps to reduce acne and the appearance of fine lines and wrinkles.
Potential side effects of mandelic acid:
Stay away from this acid if you have a nut allergy, as mandelic acid is derived from mandelic almonds. Otherwise, it is really well tolerated by all skin types.