What is salicylic acid and how does it clear up spots, clogged pores and psoriasis?

“Because a blocked pore is deep, you have to get past this waterproof barrier by mimicking the lipid structure to a degree," she notes. “An oil-soluble ingredient does just that.”

According to Dr Jason Thomson, dermatologist and Head of Medical at Skin & Me, this means salicylic acid is able to effectively penetrate deep into the skin’s pores to exfoliate the skin from within.

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What are the benefits of salicylic acid for skin?

Spots may be most visible on the surface of the skin, but they actually form inside the hair follicles. Pores that aren't properly ‘cleaned out’ often result in pimples, blackheads, whiteheads and other blemishes.

"In order to treat and reduce breakouts, you need to use blemish treatment products that will penetrate the skin," explains dermatologist and Murad skincare founder, Dr Howard Murad. For this reason, salicylic acid's ability to deeply penetrate pores and break down build-up can make such a huge difference to spots.

Alongside the work it does inside pores, salicylic acid also gently exfoliates the surface of the skin to lift away the grime and dead cells that block pores in the first place. "Clearing away the dead and dry skin on the surface allows salicylic acid to operate more effectively in clearing clogged pores, keeping oil at bay and preventing blemishes,” confirms Dr Murad.

Lastly, salicylic acid is an anti-inflammatory, which means it can calm red skin, and make pimples look less angry and the skin less raised.

Psoriasis is a common autoimmune skin condition that can lead to scaly patches on the knees, elbows, upper body and scalp. “Psoriasis causes an acceleration in skin cell turnover,” Dr Thomson explains. “Salicylic acid can be used to treat it due to its function as a keratolytic, which means it can break down the bonds holding the skin together, making it softer and allowing it to shed more easily.”

Salicylic acid also has anti-inflammatory properties, which is why it's often found in prescription creams for psoriasis as well as many over-the-counter creams.

Keratosis pilaris, commonly referred to as 'chicken skin’, is characterised by small, hard bumps on the upper arms, thighs and cheeks.

“The bumps are caused by a buildup of keratin, a key protein in skin, hair and nails,” says Dr Thomson. "In keratosis pilaris, the keratin forms a scaly plug that blocks the opening of the hair follicle, leading to patches of rough, bumpy skin.

“Salicylic acid can help improve the appearance of keratosis pilaris over time by softening and exfoliating these keratinous skin bumps,” he continues.

What is salicylic acid mainly used for?

Salicylic acid is mainly used to minimise breakouts. “When it comes to a spot, you have three factors,” says Debbie. "The first two – an overproduction of oil and excess dead skin build-up – create the blocked pore and blackhead. Then bacteria gets into the blocked pore, where it is able to grow, and the body wants to destroy it, which is when you get the redness and swelling."

The beauty of salicylic acid is that it's closely associated with aspirin, which also comes from the willow tree family. “By using salicylic acid on a spot, you can prevent and reduce the inflammation that often leads to scarring and pigmentation marks,” Debbie adds.

Can you use salicylic acid every day?

You can use salicylic acid every day but it depends on the product. Skin specialist and A-list facialist, Shane Cooper, says: “If it's a small amount of salicylic acid in a cleanser, for example, it is generally OK for everyday use. But if it is in any other skincare product, I would recommend using it in moderation as salicylic acid can sometimes irritate the skin.”

In practical terms, this means using a salicylic acid serum once a week if you have sensitive skin; otherwise start with three times a week and work up from there, adds Shane.

Are there any side effects?

With a few exceptions, salicylic acid is generally tolerated by most skin types. But there is one key side effect to be aware of.

“Salicylic acid can be drying,” says Debbie, “which may lead to flaking and then irritation, so it is important not to overuse it and to balance active products containing salicylic acid with nourishing ones.”

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Who should avoid salicylic acid?

While salicylic acid is excellent for those with oily and acne-prone skin, not all skin types can tolerate this ingredient. “You shouldn’t use salicylic acid if you are allergic to aspirin,” warns Shane. “Those with super sensitive skin or rosacea may also want to avoid it, as salicylic acid can cause irritation.”

Is salicylic acid safe to use during pregnancy?

Overall, salicylic acid is safe to use during pregnancy, says Shane. “But be aware that skin can change and become more sensitive as a result of hormone changes,” he adds.

Do you need to wear SPF if you use salicylic acid?

The short answer is yes. “Salicylic acid, like retinoids, can increase your skin's sensitivity to the sun and lead to quicker sunburns and skin damage,” Dr Thomson notes. “Use a sunscreen with an SPF of at least 30, even on cloudy days, and limit sun exposure while using products with salicylic acid.”

What is the difference between salicylic acid and glycolic acid?

Both salicylic and glycolic acids are classed as hydroxy acids and chemical exfoliants. But that's where the similarities end.

“Glycolic acid is an alpha-hydroxy acid (AHA) whereas salicylic acid is a beta-hydroxy acid (BHA) with bigger molecules as it works superficially on the skin's surface,” says GP and aesthetician Dr Ahmed El Muntasar.

“Glycolic acid has much smaller molecules so goes deeper and stimulates collagen production.”

What to look out for in your products

"Just because a product contains salicylic acid doesn’t mean it contains the right dose to be effective," says Lucy Hilson, the founder of SKN REHAB. “To work, it needs to be in a high enough percentage and concentration and not be buried in the bottom of an endless list of other ingredients. At least 0.5%-2% salicylic acid will give you a great result.”

Check out our helpful guides on banishing acne on different parts of your body, hormonal acne, back acne and how to get rid of acne scars.

In need of professional skin help? Check out our guide to every type of facial to figure out your treatment options.

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