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Salicylic acid

Salicylic acid in skincare: Exfoliant, comedolytic, preservative. What it does on skin, how strong the evidence behind the claim actually is, the concentrations in normal use, who reacts to it, and where it stands in pregnancy and sunlight. On a label it appears as Salicylic Acid.

Exfoliating acidsExfoliant, comedolytic, preservativeEvidence: Strong

On the label: Salicylic Acid. Also called: BHA, beta hydroxy acid.

This is an ingredient reference, not a diagnosis and not a treatment plan. It describes what substances are and what the published evidence supports; it does not tell you what your skin has or what to put on it. A rash that spreads, hurts, weeps, does not settle, or comes with feeling unwell is a reason to see a doctor or pharmacist, not to change serum.

What it is

A phenolic acid related to aspirin, marketed as a beta hydroxy acid. The property that matters is that it dissolves in oil, which the alpha hydroxy acids do not. That lets it travel into a pore already full of sebum and work inside it rather than only on the flat surface around it, which is why it is the acid associated with blackheads rather than with glow.

What it does on skin

Inside the follicle it loosens the compacted dead cells that form the plug, so blackheads and closed comedones clear and re-form more slowly. Being a salicylate it is also mildly anti-inflammatory, which takes some of the redness out of an inflamed spot. On the body the same keratolytic action is used at higher strengths on calluses, warts and thickened scaly skin — but those are medicines, not cosmetics.

What the evidence is worth

Evidence: Strong

Well supported for comedonal acne, the blackhead-and-bump type, and it is a standard component of acne routines in dermatology guidance. It is weaker than a retinoid for the same job and weaker than benzoyl peroxide for the inflamed, pus-filled kind. Its reputation as a general "acne cure" outruns the evidence: it does one thing well and other things not at all.

How it is used

Either as a leave-on serum or lotion at 0.5-2%, or as a cleanser where contact time is short and the effect is milder. Once daily is enough. It is a treatment for the area that breaks out, not a whole-face necessity, and using it everywhere on dry skin is the usual reason people end up with a wrecked barrier.

Typical concentration in normal use: 0.5-2% in leave-on products. That is a description of the market, not a recommendation, and it is not a dose.

Who reacts to it

Dryness and flaking around the treated area are the normal complaints. Genuine allergy is uncommon. It should not be used over large areas of broken or inflamed skin, and people with a known aspirin or salicylate sensitivity should be careful with it and ask a pharmacist.

Pregnancy and breastfeeding

Needs a conversation

Low-strength topical use on a limited area, such as a spot treatment, is generally treated as acceptable, while high-strength peels and use over large areas are avoided. Oral salicylates are a different question entirely. This is exactly the kind of decision to put to your midwife or doctor rather than to a website.

Sunlight

More sun-sensitive

Less photosensitising than the alpha hydroxy acids, but you are still thinning the outer layer and treating skin that is often also on a retinoid. Daily sunscreen prevents the dark marks that outlast the spots themselves.

Rules and labelling

In the EU salicylic acid is a restricted substance: capped at 3% in rinse-off hair products and 2% in most other cosmetic products, and not permitted in products for children under three years except shampoos. It is separately permitted as a preservative at a lower concentration, which is why you sometimes see it near the end of an ingredient list rather than the start.

What it goes with, and what it does not

It works well alongside benzoyl peroxide used at a different time of day, and alongside niacinamide, which takes the edge off the dryness. Stacking it with a retinoid, an AHA and a scrub in the same routine is how people arrive at a red, stinging face and blame the wrong ingredient.

One thing people get wrong

The myth is that if a little dries up a spot, more will dry it up faster. Acne is not a surface hygiene problem and drying skin out does not empty a follicle; it triggers more irritation, more inflammation and more of the dark marks that people then treat as a separate problem. Twice the frequency does not buy twice the result.

Sources: EU Cosmetics Regulation (EC) No 1223/2009 and its annexes, as published in the European Commission's CosIng database, for every statement about what is permitted, restricted or banned · opinions of the Scientific Committee on Consumer Safety (SCCS) and safety assessments of the Cosmetic Ingredient Review (CIR) for the concentration positions · standard dermatology reference material for mechanism, tolerability and contact-allergy patterns · checked 2026-09-06. Deep links are deliberately omitted where a stable public URL could not be confirmed.

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