How Does Salicylic Acid Work, Exactly?

The first zit treatment most of us encounter: The goopy white stuff that you quickly learn bleaches your sheets and towels (shoutout to benzoyl peroxide!). Once you've ruined enough linens, one usually smartens up and moves along to other acne treatments. And that's when you might hear about salicylic acid, one of the singe most effective acne treatments available. But what is salicylic acid? And does it have applications beyond your skin blemishes? With the help of dermatologists Joyce Imahiyerobo-Ip of Vibrant Dermatology and Skin Bar MD in Boston and Cheri Frey of Advanced Dermatology in Maryland, we put together a guide.

What is salicylic acid?

From a molecular standpoint, salicylic acid is a naturally occurring compound found in plants that's part of a family of compounds considered phenolic acids and beta hydroxy acids, explains Frey. Which is all to say, it's a gentle chemical exfoliant.

"On the skin, those acids break apart cellular connections, causing dead skin cells to slough off," Frey continues. "Salicylic acid is also soluble in oil, so it has the ability to penetrate oil glands and unclog pores."

There is some research to suggest that salicylic acid has anti-inflammatory benefits, which means it could help quell skin redness and irritation, too.

How is salicylic acid used?

Over the counter, salicylic acid is available in concentrations anywhere from 0.5 percent to 2 percent, and is found in spot treatments, cleansers, body washes, masks, lotions and creams. In these topical products, salicylic acid works to "exfoliate, increase skin cell turnover, and can help to give you a brighter, smoother complexion," says Imahiyerobo-Ip.

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What are the benefits of salicylic acid?

Because of its oil solubility, salicylic acid is particularly effective against comedonal acne —whiteheads and blackheads—where the blemishes are attributed to clogged pores and lagging skin turnover. Acne related to inflammatory issues, which manifests as painful acne cysts and pustules, is best addressed with benzoyl peroxide.

"Salicylic acid is also used at a 20 or 30 percent concentration for a chemical peel that at your dermatologist’s office," Imahiyerobo-Ip continues, nothing that the professional treatments effectively address both acne and hyperpigmentation.

Are there downsides to salicylic acid?

"Because salicylic acid has a low pH, it can be irritating to the skin," explains Frey, noting that this is why concentrations above 2 percent aren't offered commercially. "In patients with darker skin, that irritation can lead to hyperpigmentation."

If you're layering salicylic acid with other topicals like glycolic or retinoic acid, it can also leave your skin dry and irritated, so work with a dermatologist to create a targeted layering approach. Also: Salicylic acid can be absorbed by the skin, so it's not recommended during pregnancy.

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What are the best products with salicylic acid?

"My personal favorite is La Roche Posay's cleanser. It contains their patented lipohydroxy acid, which is derived from salicylic acid. LHA stays on the top layer of the skin, so it delivers more potent effects without the irritation. It also has anti-aging properties similar to retinols by stimulating hyaluronic acid and collagen production," says Frey.

As for Imahiyerobo-Ip: "Neutrogena makes a great acne body wash with salicylic acid that's super affordable. I also like Murad’s blemish control spray. Hydropeptide’s serum contains salicylic acid and azelaic acid to gently treat and prevent mild breakouts."

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