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Exfoliating acids

Salicylic acid (BHA)

Also listed as BHA, beta-hydroxy acid

An oil-soluble exfoliant that gets into pores. At 0.5-2% it is an approved over-the-counter acne ingredient with a modest but real benefit.

Moderate evidenceTypical strength: 0.5-2% leave-on

What it is

Salicylic acid is a beta-hydroxy acid (BHA). Unlike AHAs it dissolves in oil, so it penetrates the sebum in pores and loosens the plug of cells behind blackheads and whiteheads. It is also mildly anti-inflammatory (it is chemically related to aspirin).

In the US it is an approved over-the-counter acne ingredient at 0.5-2%, and at higher strengths it treats dandruff, warts and calluses; clinic peels use 20-30%. In body lotions for rough, bumpy skin it works as a keratolytic, softening thick scale.

How strong is the evidence?

Moderate evidence

It has long clinical use and a place in acne guidelines: the 2024 American Academy of Dermatology guideline gives it a conditional recommendation (lower-certainty evidence), behind benzoyl peroxide and retinoids. A 2020 Cochrane review found only small, low-quality head-to-head trials. Peel studies support benefits for acne and sun damage.

What it's used for, checked

Blackheads and whiteheads

Holds up

Its oil solubility suits clogged pores; the effect is modest.

Inflammatory acne

Mixed

Weaker than benzoyl peroxide or retinoids; best as one part of a routine.

Rough, bumpy body skin

Holds up

Its keratolytic action softens thick scale and rough bumps.

Dandruff and scalp flaking

Holds up

An approved over-the-counter dandruff ingredient that loosens flakes.

Shrinking pores

Unproven

Clearing debris can make pores look smaller; pore size is set mostly by genetics, age and oil output.

Works well with

  • Niacinamide
  • Benzoyl peroxide (alternate days if skin gets dry)
  • An oil-free moisturizer

Don't combine with

  • Layering other exfoliating acids and retinoids at the same time — irritation

Who should be careful

  • Salicylate poisoning (salicylism) from skin products is rare but reported, including deaths; the risk rises with high strengths, large areas, occlusion and use on children.
  • People allergic to aspirin should ask a clinician before using it.
  • In pregnancy, low-strength face products are generally considered acceptable; avoid high-strength peels and large-area body use.
  • Dryness and irritation are common with daily 2% use combined with other actives.

The studies

Every citation is checked against its PubMed record.

  1. Guidelines of care for the management of acne vulgaris.
    Reynolds RV, Yeung H, Cheng CE, Cook-Bolden F, Desai SR, Druby KM, et al. · Journal of the American Academy of Dermatology · 2024 · Guideline

    The American Academy of Dermatology's acne guideline makes strong recommendations for benzoyl peroxide, topical retinoids, topical antibiotics and oral doxycycline, and conditional (lower-certainty) recommendations for topical salicylic acid, azelaic acid and clascoterone.

  2. Topical azelaic acid, salicylic acid, nicotinamide, sulphur, zinc and fruit acid (alpha-hydroxy acid) for acne.
    Liu H, Yu H, Xia J, Liu L, Liu GJ, Sang H, Peinemann F · Cochrane Database of Systematic Reviews · 2020 · Systematic review

    49 trials (3,880 people): azelaic acid is probably less effective than benzoyl peroxide and about as effective as tretinoin for acne; evidence for salicylic acid, nicotinamide and alpha-hydroxy acids was low or very low quality, from small head-to-head trials, and no conclusions were reported for zinc or sulphur.

  3. A review of toxicity from topical salicylic acid preparations.
    Madan RK, Levitt J · Journal of the American Academy of Dermatology · 2014 · Review

    Reviews salicylic acid toxicity from skin products: salicylism, and even death, can occur from topical use, although it is rare; how much is absorbed depends on the vehicle and conditions of use.

  4. Salicylic acid as a peeling agent: a comprehensive review.
    Arif T · Clinical, Cosmetic and Investigational Dermatology · 2015 · Review

    Reviews salicylic acid peels for acne, melasma, photodamage and freckles, including their documented efficacy and safety in both lighter and darker skin types, side effects and salicylism.