Dermatologists Say This Star Acne-Fighting Ingredient Can Also Be Used To Treat Dandruff And Psoriasis

The best at-home skincare routine for acne must include a few essential elements. First, you'll need a good acne face wash to cleanse away pimple-causing bacteria and pore-clogging dirt and oil. Next, you'll need a good retinol cream for nighttime use. But most importantly, you'll want to find a way to work salicylic acid into your regimen. The oil-soluble beta-hydroxy acid can deep-clean pores to send pimples packing.

But this wonder ingredient can do more than just keep skin clear. "Salicylic acid is a topical medication used to treat acne and a variety of other skin conditions, like warts and psoriasis," says double-board-certified dermatologist, Maya Thosani, MD. While it's a very common, you may have a few questions about how to incorporate the ingredient into your skincare routine.

To give you some, well, clarity, we spoke to two experts to give us the low-down on how to use salicylic acid. Read ahead to find out what we learned.

Meet the experts: Maya Thosani, MD, is a double-board-certified dermatologist and owner of Modern Dermatology in Scottsdale, Arizona. Mina Amin, MD, is a board-certified dermatologist based in Los Angeles, California.

What is salicylic acid?

Salicylic acid is the most common type of beta hydroxy acid (BHA). “It’s known for its ability to penetrate the skin and exfoliate, making it a great option for treating acne and oily skin,” says board-certified dermatologist Mina Amin, MD. Like alpha hydroxy acids (AHAs), salicylic acid’s purpose is to exfoliate the skin, but the major difference is that BHAs are oil-soluble (AHAs are water-soluble), meaning they can dissolve the oil and debris deep within the skin that can eventually cause acne and other types of raised bumps.

Unlike some other acne-fighting ingredients that require prescriptions for regular use, salicylic acid is ubiquitous in over-the-counter products. Because there are so many options for home use, “we typically don’t need to prescribe salicylic acid for acne,” Dr. Amin explains. “There are prescription salicylic acid shampoos that can be used to treat psoriasis or dandruff. Higher percentages are also considered to treat warts on the body.”

When you're shopping for a salicylic acid product, the concentration you should look for depends a lot on what you’re hoping to treat. “Most acne treatments—like cleansers, spot treatments, and lotions—contain salicylic acid in the 0.5 to two percent range,” she says. “One to two percent is common for spot treatments and more localized applications. In exfoliating toners or serums, 0.5 to two percent is effective for maintaining clear skin without excessive irritation.”

In medicated shampoos and creams that treat psoriasis and dandruff, you’re more likely to find it at a higher concentration, like three percent.

What are the benefits of salicylic acid?

While salicylic acid is typically recommended as an acne treatment, that’s definitely not all it’s good for. The ingredient can be used to treat and control the following:

• Fights acne: This is probably one of salicylic acid’s most well-known benefits. More specifically, it’s a star ingredient for treating comedonal acne like whiteheads and blackheads, which are usually caused by the pores becoming clogged with oil, dead skin, and dirt. When applied topically, it can deeply penetrate the skin to clear out all of that gunk, and in some cases, stop acne in its tracks. “It breaks up the sebum—dead skin and oil that combine into a sludge that clogs pores—to help unclog them,” says Dr. Thosani. It’s also anti-inflammatory, “so it reduces any redness and swelling associated with acne,” says Dr. Amin.

• Removes warts: Warts are commonly caused by the human papillomavirus (HPV). Most dermatologists may recommend freezing them off via cryotherapy, but you can also use OTC products featuring salicylic acid to get the job done. Per Dr. Thosani, salicylic acid works to "mildly irritate the skin and trigger the immune system to fight the virus," and when applied topically, it can peel off the skin of the wart in layers. For this to work though, you'd have to find a product with a higher concentration of the ingredient, between 17 and 40 percent.

• Controls excess oil and sebum: If your skin isn’t quite acne-prone but is still on the oilier side, there’s a good chance you’ve also been advised to invest in a lot of salicylic acid products. Again, that’s because it’s an oil-soluble ingredient, meaning that it’s easily able to regulate oil and sebum on the skin.

• Reduces symptoms of keratosis pilaris (KP): Keratosis pilaris is a condition that’s characterized by bumpy skin on the arms, legs, or butt, and it's caused by a buildup of keratin in the hair follicles. While there’s no treatment to make it go away entirely, Dr. Thosani says that salicylic acid can help exfoliate "dry, scaly, or thickened skin."

• Treats plaque psoriasis: Psoriasis is an auto-immune disease that causes inflammation. In its most common form, plaque psoriasis, it shows up as thick, scaly areas— plaques—on the skin. According to Dr. Amin, people with psoriasis might gravitate toward salicylic acid products because they can help reduce the scaling and inflammation associated with the condition.

• Reduces dandruff: Dandruff is usually caused by an overgrowth of yeast on the scalp, but it can also be attributed to oiliness, which can build up and cause the area to become flaky and scaly. "A salicylic acid shampoo can help break up the scales and minimize flaking," says Dr. Thosani. Because salicylic acid breaks down oil, it can help regulate the amount of sebum produced by the scalp.

Can salicylic acid be used to treat dark spots?

Sort of. While it's not the first thing your doctor might tell you to reach for when treating hyperpigmentation and dark spots, it definitely can play a role in a larger skincare regimen to help treat it, says Dr. Thosani.

"Salicylic acid peels performed to treat acne not only the breakouts, they can also prevent post-inflammatory hyperpigmentation," she adds. "However, if salicylic acid is used too much or results in irritated, dry skin, it can cause hyperpigmentation, especially in darker skin tones, so it should be used judiciously under the guidance of your dermatologist."

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How to use salicylic acid

As previously mentioned, you can find salicylic acid in products like cleansers, toners, and serums.

• In cleansers: If you’re using a salicylic acid cleanser, Dr. Amin recommends only using it once a day, in the morning or at night. “Wet your face, apply the cleanser, and gently massage it in for about 30 seconds,” she says. “Rinse thoroughly.”

• In toners: If you’re using toners or toning pads, you should use them once a day, typically at night. “After cleansing, apply the toner with a cotton pad, avoiding the eye area,” Dr. Amin says. “Allow the toner to absorb before applying other products, like serums or moisturizers.”

• In serums: You should use a salicylic acid serum once a day after cleansing and toning. “Apply a few drops of the serum to your fingertips and gently press it into your skin,” Dr. Amin says. “Allow the serum to fully absorb before applying moisturizer.”

Keep in mind that salicylic acid is an active ingredient, so it has potential to be slightly irritating. If you’re using it for the first time, Dr. Thosani recommends starting off slow, using it once or twice a week to see how your skin reacts to it. You should also avoid using it in conjunction with ingredients like retinoids. “Using these together can increase skin sensitivity and irritation,” says Dr. Amin. Ditto for AHAs like glycolic and lactic acids, as these using these together can lead to over-exfoliation and irritation, per Dr. Amin.

On the flip side, Dr. Amin says that salicylic acid is generally safe to use alongside ingredients like hyaluronic acid (because it’s an ultra-hydrating ingredient that helps to mitigate dryness that can be caused by SA) and niacinamide (which is known for addressing irritation and redness). Also on the safe-to-mix list are peptides, which support skin barrier function.

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