Face acids may just be the key to more luminous, happier skin. But which one is right for you?
The word “acid” may conjure images of scary, bubbling test tubes, but when used at the right concentrations, acids are actually some of the most beneficial ingredients available in skin care.
They’re used to fight acne, wrinkles, age spots, scarring, and uneven skin tone. But with so many acids on the market, it can be overwhelming to know what kind to use and for what.
Here’s where to start.
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%, as well as in spot treatments for breakouts.
In dermatology clinics, salicylic acid is also used in higher concentrations as a peeling agent for treating acne, acne scars, melasma, sun damage, and age spots.
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 provides great support for aging skin.
It’s effective at exfoliating skin and reducing fine lines, fading dark spots, preventing acne, increasing skin thickness, and evening out skin tone and texture. It’s in many cult skin care products and commonly found at concentrations below 10%.
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 it’s even more important to layer on that sunscreen.
Mandelic acid, derived from bitter almonds, is another alpha-hydroxy acid. Like glycolic acid, it’s an exfoliating agent that’s useful for preventing acne, treating sun damage, and evening out pigmentation.
Due to its larger molecular structure, it doesn’t sink into 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 darker skin tones, which are 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 be ineffective and often causes it to have the opposite of the intended effect.
Azelaic acid has been a mainstay treatment for moderate acne for the last 3 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% concentrations in creams 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 or other color changes.
Azelaic acid is also a
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
It’s found in cleansers and serums at 1% to 4% concentrations, and though it’s effective, it can be very irritating to skin.
Ascorbic acid is the most common water-soluble form of vitamin C. It’s used in skin care for its pro-aging support and as a
Ascorbic acid is very unstable in the presence of oxygen and water, so it’s commonly available in more stable forms under the names 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:
| Acids | Benefits |
|---|---|
| lactic, citric, malic, and tartaric acids | AHAs that act as exfoliants also work to lighten uneven pigmentation and smooth out skin texture. Lactic acid is the best-researched AHA after glycolic acid, and is notable for being gentler, more hydrating, and |
| ferulic acid | An antioxidant ingredient that’s most commonly used in conjunction with vitamins C and E in serums. This powerful antioxidant trio is known for its ability to protect the skin from the damaging free radicals generated by UV radiation. |
| lipoic acid | An antioxidant ingredient with pro-aging support. Its effects are quite modest, so its popularity is waning. |
| trichloroacetic acid (TCA) | TCA is used in peels and is especially useful for flattening out scars in the |
| alguronic acid | A byproduct of biodiesel production, it’s reported to have “anti-aging” effects, but peer-reviewed research has yet to support these claims. |
Linoleic acid and oleic acid: The assistants
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 and 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 to penetrate the skin.
The hard part is choosing which acid to use. The easiest way to do this is to know what problem you want to treat.
| Best for… | Acid |
| acne-prone skin | azalaic acid, salicylic acid, glycolic acid, lactic acid, mandelic acid |
| mature skin | glycolic acid, lactic acid, ascorbic acid, ferulic acid |
| fading pigmentation | kojic acid, azelaic acid, glycolic acid, lactic acid, linoleic acid, ascorbic acid, ferulic acid |
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 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 you’ve purchased some new products, remember not to put them all on at the same time! Some acids may interact with others.
Don’t mix face acids
- Don’t use salicylic acid with any other acid at the same time. When mixed, extreme skin irritation may occur.
- Avoid salicylic acid with products that contain niacinamide.
- Don’t use glycolic acid or lactic acid in combination with ascorbic acid (vitamin C). This will cause the ascorbic acid’s benefit to disappear even before it begins to work.
- If formulated together, products with AHAs and retinol can be used, but to
minimize irritation , they should be used no more than every other day.
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 times.
Face acids are an important skin care ingredient. They can help even out skin tone, reduce acne, wrinkles, age spots, scarring, and even help with some signs of aging.
Choosing what acid to use depends on the skin concern you want to address. Don’t mix face acids and always start with lower-strength products so as not to irritate your skin. Some acids increase sun sensitivity, so make sure to wear sunscreen, even on cloudy days.