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Ingredient glossary

Salicylic acid (BHA)

What Salicylic acid (BHA) does for your skin, who it suits, and what to watch for.

INCI: Salicylic Acid · Also: BHA

Solid and proven

In short: Salicylic acid (BHA) delivers anti acne and exfoliation, suits combination and oily skin best, and the evidence behind it is moderate. One thing to know: clear it with your doctor if pregnant; introduce it gently.

What it does
Anti acne, exfoliation
Best for
Combination, Oily skin
Watch out
Clear it with your doctor if pregnant; introduce it gently
Evidence
Moderate
How long
Never measured
Does it clash with what you use? Check it →

Written by Maya Faour, founder and sole writer; not a dermatologistHow we work →

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The molecule

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The Glow take

One of the ingredients I trust most.

When your goal is calming breakouts and congestion, Salicylic acid (BHA) delivers, with a solid amount of evidence behind it. Introduce it gently, and pair it with something soothing if your skin runs sensitive.

— Maya

What it does

  • anti acne
  • exfoliation

moderate evidenceSalicylic acid has decades of use and some older placebo-controlled support for clearing comedones, but the 2024 American Academy of Dermatology guideline…

Why we say this
  • Salicylic acid has decades of use and some older placebo-controlled support for clearing comedones, but the 2024 American Academy of Dermatology guideline recommends it only conditionally, on low-certainty evidence from a single randomised trial — unlike benzoyl peroxide and retinoids, which it recommends strongly.
  • The 0.5–2% figure is the concentration range the US OTC acne monograph permits (21 CFR 333.310), not a measured effective dose; in EU cosmetics 2% is a safety ceiling rather than a target.

On a label: works best above 0.5%.

How much do you need?

0.5%+

The vehicle-controlled trials worked from 0.5%; no published dose comparison sets a ceiling.

The trials, and what they used
  • Floor 0.5%, the pad maker's own reading: A review of four clinical studies and a comedolytic assay attests to the efficacy and safety of 0.5% and 2% solutions of salicylic acid for the treatment of acne vulgaris.
  • (Zander 1992: three placebo-controlled pad studies at 0.5% and 2%, unpublished, summarised by the maker; the US 0.5 to 2% acne monograph, 21 CFR 333.310, rests on them).
  • No independent vehicle-controlled trial of a leave-on salicylic acid at a stated percentage is published.
  • What is published pins 2% against approved actives: a 2% salicylic acid hydrogel matched adapalene gel on lesion clearance in 500 patients over 12 weeks (Ye 2024), a 2% cream with 0.5% chloroxylenol matched 5% benzoyl peroxide in 37 patients over 12 weeks, double-blind (Boutli 2003), and a 2% cleanser reduced comedones where a 10% benzoyl peroxide wash did not in a 30-patient crossover (Shalita 1989).
  • No dose comparison found.
  • EU Annex III/98 (Regulation 2022/1181, after SCCS/1601/18) allows 2% in leave-on products and 3% in rinse-off hair products; a regulatory ceiling, not an effect ceiling.

Read the full reasoning →

The pH it needs

The un-ionised acid (pKa about 2.9) crosses skin; as pH rises more of it is ionised and flux falls (pH 2 > 5 > 7 in excised human skin).

your skin<5 · excised human skin23456789pH

pH 5.0 is above 5, past the line the study drew (excised human skin).

SA was dissolved in phosphate buffer solutions of pH 2, 5 and 7 (2 mg/ml).

Drag the handle along the line. Only what was measured is drawn; between the marks nothing was. Your skin's surface: about 4.7 at rest, 5.1 on a normal day.PMID 18489300PMID 14706244

All the measured windows on one line →

Who it's for, and who should skip it

Tends to suit

  • oily
  • acne prone
  • combo

Approach with care

  • very sensitive
  • compromised barrier
  • pregnancy high
  • Clogs poresLow
  • Irritation riskModerate
  • pH-dependentIts effect depends on the product's pH

How it fits each skin type

  • DryNeutral
  • CombinationSuits
  • OilySuits
  • SensitiveTake care

Often chosen for acne prone. Take extra care if any of these apply to you: compromised barrier, pregnancy (in high amounts).

Where it fits in your routine

WhenEvening
Where in the orderAfter cleansing, before your moisturizer

Salicylic acid does not increase sun sensitivity. That has been measured directly, and at higher strengths it slightly reduces UV reaching the skin. The sunburn warning you see on exfoliants is written for the alpha hydroxy acids, which salicylic acid is not.

Why we say this

Kornhauser et al., J Dermatol Sci 2009 (FDA/CFSAN), 14 volunteers, MED + sunburn cells + CPDs; Eur J Dermatol 2002, 20% salicylic acid raised MED; CIR salicylic acid assessment: 'not a photosensitizer, nor is it phototoxic'; FDA AHA labelling guidance, scoped to AHAs

Nobody has published how long this takes to work.

What is known, and what is missing
  • Measured on: acne lesion counts, comedonal and inflammatory.
  • Nothing published dates this ingredient.
  • The salicylic-acid-specific citation in this base is not a trial but a manufacturer review: staff of the company selling the salicylic acid pads summarising four studies, three of them placebo-controlled but unpublished, with no timepoints given.
  • The 2024 AAD acne guideline recommends topical salicylic acid only conditionally, on low-certainty evidence from a single randomised trial, and says nothing about when a user should expect lesion counts to fall.
  • The modern randomised literature does not fill the gap: it is either a different exposure entirely (20-30% in-office peels), an active comparator with no vehicle arm (adapalene, benzoyl peroxide), or a multi-ingredient formula in which salicylic acid cannot be separated.
  • The 8-12 week figure that circulates is the standard length of an acne trial and the interval at which clinicians reassess any acne therapy - a design convention carried over from better-studied molecules, not a measurement of this one.
  • The keratolytic effect on an individual comedone is faster than any of that, and nobody has published it as a timed endpoint either.
  • What is missing specifically: a vehicle-controlled trial of a 0.5-2% leave-on or cleanser reporting lesion counts visit by visit.

PMID:1535287 (Zander & Weisman, Clin Ther 1992;14(2):247-53 - a manufacturer-authored review of four studies, no timepoints) and PMID:38300170 (AAD 2024 acne guideline - conditional recommendation, low-certainty evidence from a single randomised trial, no onset statement); both read against the claim. No vehicle-controlled trial of 0.5-2% leave-on salicylic acid reporting lesion counts by visit was located on PubMed.

What regulators say

In the EU salicylic acid (BHA) is capped at 3.0% in rinse-off hair products, 2.0% in other products and 0.5% in body lotion, eye shadow, mascara, eyeliner…

What the regulator says, in full
  • In the EU salicylic acid (BHA) is capped at 3.0% in rinse-off hair products, 2.0% in other products and 0.5% in body lotion, eye shadow, mascara, eyeliner, lipstick and roll-on deodorant, when used for purposes other than preservation (Annex III entry 98 as amended by Regulation 2021/850); as a preservative 0.5% (Annex V entry 3); not for children under 3, not in oral products, not in sprays that reach the lungs.

Plays well with

Salicylic acid (BHA), answered

Is Salicylic acid (BHA) safe during pregnancy?

Clear it with your doctor first. Salicylic acid (BHA) is flagged as use-with-caution during pregnancy and breastfeeding, so check with your doctor or midwife before adding it.

Who should avoid Salicylic acid (BHA)?

Approach Salicylic acid (BHA) with care if any of these apply to you: very sensitive, compromised barrier, and pregnancy (in high amounts). Its irritation risk is moderate, so introduce it slowly and patch test first.

What concentration of Salicylic acid (BHA) actually works?

Research tends to show Salicylic acid (BHA) starts pulling its weight above 0.5%. If a brand prints the percentage, that is the number to look for.

During pregnancy

Treat Salicylic acid (BHA) as a maybe rather than a yes for now. It is flagged as one to use with caution while pregnant or breastfeeding, so it is worth clearing before you carry on.

When in doubt, check with your doctor or midwife. They outrank any website, including this one.When it is worth booking →

Commonly confused with

  • Glycolic acidSalicylic is oil-loving and works inside the pore (a BHA). Glycolic works on the surface (an AHA).
  • Benzoyl PeroxideBoth fight breakouts, differently. Benzoyl peroxide kills acne bacteria; salicylic acid unclogs the pore.

More skincare terms people mix up →

Readers asked about Salicylic acid (BHA)

On the map

See Salicylic acid (BHA) on the clash map →

Compare Salicylic acid (BHA) with

15 comparisons built, the 5 most looked-up above.

Can you mix Salicylic acid (BHA) with

30 pairings built, the 5 most looked-up above.

Products with Salicylic acid (BHA)

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Sources & how we reviewed this

  1. 21 CFR 333.310 (US federal regulation)read in full
  2. PMID 38300170abstract read, not the full text
  3. PMID 1535287abstract read, not the full text
  4. SCCS/1601/18 (EU Scientific Committee opinion)summary page only, the document itself was not read

Last reviewed . Educational information about a cosmetic ingredient, not medical advice.

What changed on this page

  • : the pH it needs
  • : the effective dose from trials, the highest dose tested
  • : what the EU regulates

See the full changelog →