Everything You Really Need to Know About Salicylic Acid

Curated by Claudia Shannon / Research Scientist / Honayst

What is salicylic acid, and how does it work?

Salicylic acid sits within the skincare acid family, but it is different from others. Glycolic, lactic and mandelic are all alpha hydroxy acids, whereas salicylic is classified as a beta hydroxy acid: in fact, it’s the only one used in skincare. “Naturally sourced from willow tree bark, this fat-soluble beta hydroxy acid penetrates follicles to break down oil build-up, reducing and preventing pore blockages,” explains dermatologist Dr. Dennis Gross.

Of course, salicylic acid is famed for its spot-fighting powers, but a good product will actually do much more than shrink down an angry spot, as Dr. Gross explains. “A keratolytic agent, salicylic acid reduces the pH of skin and increases hydration as well as the process of desquamation (the shedding of dead skin cells). It can also directly dissolve keratin plugs (known as keratosis pilaris) and regulate skin cells to fight acne and blemishes."

What are the differences between an AHA and a BHA?

AHAs and BHA work on different levels on the skin, hence their differing classification. AHAs are water-soluble acids (commonly derived from sugar cane, milk and citrus fruits). They work on the surface of the skin, dissolving the desmosome bonds – think of them as the glue that holds dead skin cells together – revealing the fresher skin just beneath. BHA is oil-soluble and so works on both the surface and deeper inside the pore, dissolving the trapped debris and excess sebum that leads to breakouts.

What skin types should use salicylic acid?

“Salicylic acid is suitable for use on all skin types, but it’s especially effective on blemish prone and uneven types as it helps to prevent pore blockages and contains anti-inflammatory properties.” says Dr. Gross. However, anyone with an allergy to aspirin should avoid products containing salicylic acid, as they both belong to the same family of compounds (and so your skin may be intolerant).

How to use salicylic acid at home

Traditionally, salicylic acid has been widely used in on-the-spot blemish gels and treatments, but now its powers are being harnessed for prevention as well as cure. A salicylic acid cleanser is a good ally for acne-prone skin types, as it’ll help keep pores consistently clear, preventing breakouts before they occur. A serum is another good option, while easily overloaded skin will love a water-weight toner or treatment mist.

1 The booster serum Night Switch BHA/AHA 10%

This night serum contains a trio of acids that work together to clarify breakout-prone skin. Lactic (a gentler AHA than glycolic) works on the surface, while salicylic penetrates the pores and azelaic acid reduces inflammation. Use it a few nights per week, ideally beneath the brand’s simple yet effective Universal Emulsion moisturiser.

2 The cleanser Blemish and Age Cleanser

This smart gel cleanser feels instantly cooling on congested skin. It's formulated with both glycolic and salicylic acids, so delivers a multi-level exfoliation while sweeping away grime and pollution.

3 The clarifying toner 2% BHA Liquid Exfoliant

This BHA toner is one of Paula Begoun’s most-loved products. Refreshingly simple yet highly effective, the almost gel-like liquid contains pore-clearing beta hydroxy acid alongside a handful of hydrating and calming ingredients. It's a cult hero for very good reason.

4 The on-the-spot gel Breakout Clearing Gel by Dr Dennis Gross

There are plenty of salicylic acid spot treatments lining the shelves, but many tend to dry out the skin surrounding a blemish, leaving redness or flaking to occur. This supremely fast-acting gel contains both salicylic and glycolic acids, so works on multiple layers of the skin to unclog, soothe and heal a breakout.

5 The multi-acid mask Super Pore-Detox Purifying Black Clay Mask

This weekly purifying mask contains a host of ingredients that work together to absorb grime and excess sebum, dissolve dead skin cells and calm breakout- related inflammation. A combination of glycolic, lactic and salicylic acids is steeped in a kaolin clay base: it's not for the very sensitive, but most skin types should see impressively brighter, clearer skin.

6 The daily serum EradiKate Salicylic Acid Blemish Treatment

Kate Somerville's typically considered salicylic acid serum combines BHA with moisture-grabbing algae extracts and hyaluronic acid, which balance the skin barrier while clearing impurities. Swipe it over areas of congestion, or use it all-over to refine overly enlarged pores.

7 KILLA™ Kit

There are several pimple patches on the market today, but these are by far the most advanced. Each emergency breakout sachet contains a pre-treatment swab to cleanse the area, steeped in tea tree and salicylic, and an adhesive ‘Killa’ patch, which uses microdart technology to send a dose of niacinamide and salicylic acid straight to the root of the breakout. Call on these when you need a reliable overnight fix.

8 The blackhead treatment BHA Blackhead Power Liquid

A K-Beauty leader, Cosrx is a go-to for no-nonsense skincare that truly deserves its cult status (even Emily Ratajkowski is a fan). The ingredients list on this spritz-on blackhead treatment is exemplary: it boasts a gentle, diluted level of of salicylic acid alongside humectants and soothing willow bark water. There’s an excellent salicylic acid cleanser in the line, too.

9 The swipe-on pads Blemish Control Pads

These swipe-on salicylic acid pads are one of the easiest ways to clarify skin: they're pre-soaked so you're getting the perfect dose every time. Crucially, they're free from drying alcohols that can make breakouts worse, and loaded with salicylic acid as well as glycerin and allantoin to bring down redness and inflammation. Use one each evening, allowing the solution to dry on the skin before applying a gentle moisturiser.

10 The body treatment Alpha Beta Exfoliating Body Treatment

Dr. Dennis Gross has reformulated his cult Alpha Beta exfoliating wipes specifically for the body. Apply them to areas of keratosis pilaris, body acne or simply stubbornly rough skin for a quick, satisfying transformation.