Face Acids: Types, Benefits

The word “acid” conjures up images of bubbling test tubes and thoughts of scary chemical burns. But when used at the right concentrations, acids are actually some of the most beneficial ingredients available in skin care.

They’re the miracle tools used to fight acne, wrinkles, age spots, scarring, and uneven skin tone. But with so many acids on the market, it can seem overwhelming to remember which to use — and for what — and which products to buy. Before all that, you have to know where to start.

The most well-known acne cleanser

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Salicylic acid* has been around for a long time. It’s well-known for its ability to exfoliate the skin and keep pores clear, which helps reduce acne. You’ll find it in serums and cleansers at concentrations between 0.5 and 2 percent, as well as in spot treatments for breakouts.

Salicylic acid* is also used in higher concentrations as a peeling agent for treating acne, acne scars, melasma, sun damage, and age spots in dermatology clinics. It’s so effective that it’s used in wart and corn removal solutions, although it’s still safe to use in pigmentation-prone dark skin. Since it’s related to aspirin (acetylsalicylic acid), it also has anti-inflammatory properties.

The fantastic anti-aging weapon

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Glycolic acid is the most popular alpha-hydroxy acid (AHA) used in skin care. It comes from sugar cane, and is the smallest AHA, so it’s the most effective at getting into the skin. Glycolic acid is a fantastic anti-aging agent that seems to do it all.

It’s very effective at exfoliating skin and reducing fine lines, preventing acne, fading dark spots, increasing skin thickness, and evening out skin tone and texture. So it’s no surprise that you’ll find it in many cult skin care products. It’s commonly found at concentrations below 10 percent.

Much like salicylic acid*, glycolic acid is also used in peels for treating acne and pigmentation, sometimes in tandem with microdermabrasion or microneedling. However, use of glycolic acid increases sun sensitivity even when it’s not on the skin, so you need to use sunscreen as well to prevent extra sun damage.

The smoothening exfoliant for even skin

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Mandelic acid* is another alpha-hydroxy acid, one that’s derived from bitter almonds. Like glycolic acid, it’s an exfoliating agent that’s useful for preventing acne, treating sun damage, and evening out pigmentation.

However, due to its larger molecular structure, it doesn’t penetrate skin as deeply as glycolic acid*, so it’s less irritating to the skin. For this reason, it’s commonly recommended in peels instead of glycolic acid, particularly for ethnic skin which is more prone to rebound pigmentation. Rebound pigmentation occurs when a resistance is built up to a particular substance due to excessive use. This causes the substance to not only be ineffective, but often causes it to have the opposite of the intended effect.

The holy grail to saying goodbye to pimples

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Azelaic acid* has been one of the mainstay treatments for fighting moderate acne for the last three decades, and is found in many prescription-only creams. It keeps pores clear, kills bacteria, and reduces inflammation. It’s generally found at 15 to 20 percent concentrations in creams that are designed to be applied all over the face, morning and night. Azelaic acid* generally has very few side effects, but in some people with very sensitive skin it can cause stinging, peeling, and redness.

As well as treating acne, azelaic acid* is also a skin-lightening agentTrusted Source that’s useful for fading post-acne marks, or post-inflammatory hyperpigmentation. It’s frequently combined with retinoids as a milder alternative to hydroquinone.

The brightening, whitening agent

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Kojic acid* is produced by bacteria used in the fermentation of rice for the production of sake. It’s a popular ingredient in Asian skin care products thanks to its whitening and anti-aging propertiesTrusted Source. (Whitening is a term many Asian skin care brands use to refer to decreasing hyperpigmentation and uneven skin tone.)

It’s found in cleansers and serums at 1 to 4 percent concentrations. Unfortunately, it’s very irritating to skin — but it’s also very effective.

The sister to vitamin C

Ascorbic is the most common water-soluble form of vitamin C, and is used in skin care for its anti-aging effects. It’s also been used as a substitute for hydroquinone in treating melasma. Ascorbic acid is very unstable in the presence of oxygen and water, so it’s commonly available in more stable forms under the name magnesium ascorbyl phosphate and tetra-isopalmitoyl ascorbic acid.

Here are some other skin care acids that may be on the market. These acids may not be as popular, so they may be harder to find in common skin care lines and products, but there’s still evidence that they work:

Linoleic acid and oleic acid*, the assistants to transporting benefits

When talking about linoleic acid* and oleic acid* in skin care, it’s mostly in the realm of oils, where they aren’t true acids per se. In oils, these fatty acids have reacted to lose their acid groups, to form triglycerides. Generally, oils that contain more linoleic acid* have drier textures that suit oily skin, while oils that contain more oleic acid* feel richer and work better for dry skin.

Linoleic acid* on its own has pigmentation-lightening properties, but since it’s already found in oils, you’ll need to use a product that’s free of linoleic acid* to achieve the same effect. Oleic acid on its own is a barrier disruptor that’s useful for helping drugs penetrate the skin.

Which acid should I use?

Choosing which acid to use is the hard part. The easiest way to go about it, is by knowing what problem you want to treat.

Pro-tip: The higher the concentration, the more likely the acid will irritate the skin. Always patch test and start with a lower concentration before moving up.

Many acids offer multiple benefits and since they can come in many different formulations it’s possible to use more than one. Brands will often advertise the active acids in cleansers, serums, toners, and more, but check the ingredient list to make sure the acid is the active ingredient — listed near the top, and not a forgotten side character at the very end of the list.

What to know about mixing acids in your skin care routine

After your new shipment of beauty goods come in the mail, remember not to put them all on at the same time! Some acids may interact with others.

To get around this, organize your acids between daytime and nighttime use. For example, use salicylic acid* in the morning and another acid* in the evening. You’ll still get the benefits of both if you use them at separate applications.