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BHA (salicylic acid)

aka Salicylic Acid, BHA, Beta hydroxy acid, Betaine Salicylate (related salicylate), Willow bark extract (plant source of salicylates)

The short answer

BHA (salicylic acid) dissolves in oil, so it can work inside pores where blackheads and congestion form, which is why it suits oily and blemish-prone skin. Leave-on cosmetics usually contain 0.5% to 2%, and it's a different ingredient from betaine salicylate, the gentler-marketed version common in K-beauty pads.

Known for
Oil-loving acid that works inside pores for clearer, less congested-looking skin.
Suits
Oily skin
Helps with
Blackheads and congested poresBlemish-prone skin
Evidence
moderate

Updated 5 Oct 2026 · Sources

Check first

Caution: Can sting on broken skinCaution: Keep out of eyesCaution: Large-area use: check firstCaution: Aspirin sensitivity: ask a pharmacist
  • Your skin is irritated, infected, broken or red; DermNet advises against using it there.
  • You've reacted to aspirin; salicylic acid is closely related, so check with your pharmacist first.
  • You use prescription tretinoin; its Australian product information cautions against using salicylic acid at the same time.
  • You're pregnant and considering a salicylic acid peel or applying it over large areas of skin.

What it goes with

Pairs well

  • NiacinamideBoth suit oily, blemish-prone routines; no source shows a clash. Separate them if the combination stings.
  • Hyaluronic acidLightweight hydration after BHA without heaviness.
  • CeramidesA barrier-supporting moisturiser offsets dryness from exfoliation.
  • HeartleafA light, watery toner step that sits easily alongside acne-focused actives; no interaction data either way.
  • SPF50+ sunscreenSalicylic acid didn't raise sunburn cells in one study, but Australian UV means daily SPF anyway.

Keep apart

  • Avoid: RetinolThe AAD advises not exfoliating while using retinol. Alternate nights.
  • Avoid: Prescription tretinoinThe Australian tretinoin product information cautions against concurrent salicylic acid. Ask your prescriber.
  • Avoid: AHA (alpha hydroxy acids)One exfoliant per routine; stacking acids adds irritation.
  • Avoid: Tranexamic acidA clinic guide advises not applying TXA at the same time as strong AHA or BHA exfoliants.
  • Avoid: Vitamin CTwo low-pH products together can sting; use them at different times of day.

How it works

Salicylic acid is fat-soluble, which sets it apart from AHAs: it mixes with skin oils and the oil inside pores, so it suits oily skin [1][2]. Chemists point out that calling it a 'beta hydroxy acid' is technically incorrect because of its ring structure [1], but BHA is the name everyone searches for.

Rather than dissolving keratin, it loosens the connections between skin cells [2][3]. For blemish-prone skin, DermNet describes it as slowing cell shedding inside follicles and helping break up the plugs that form blackheads [3]. Reviews also describe a calming effect at 0.5% to 5% [2].

Australian use data compiled by AICIS show leave-on cosmetics at 0.5% to 3%, rinse-off products at 1% to 5% and peels up to 30%; the EU and Canada cap most cosmetics at 2% [4]. Peel-strength studies, including one in 25 people with darker skin, reported good results with few side effects [2], but we found no study measuring how much difference everyday 0.5% to 2% products make.

Unlike glycolic acid, 2% salicylic acid did not increase sunburn cells in the study where 10% glycolic acid did [1]. That's reassuring, not a reason to skip sunscreen.

Betaine salicylate, common in K-beauty toner pads, is a related salicylate, but we found no published study comparing it with salicylic acid [6]. The popular rule that 4% betaine salicylate equals about 2% salicylic acid is a rough chemistry estimate without a cited source [7].

How to use it

  • Leave-on products at 0.5% to 2% (toners, serums, pads): start two or three times a week and build up if comfortable.
  • Cleansers rinse off, so they're a gentler way to start [3].
  • K-beauty pads: check the ingredient list for salicylic acid versus betaine salicylate.
  • Moisturise afterwards and wear SPF50+ in the morning [14].
  • Keep it away from your eyes [4].
  • Don't apply it to irritated or broken skin or over large areas [3].
  • Acne-focused routines may show improvement within about six weeks, with fuller change taking two to three months [12].

FAQ

We don't know: no published study compares them [6]. The '4% equals 2% salicylic acid' rule is a rough estimate without a cited source [7].

Products with bha (salicylic acid)

Each links to Australian stockists, with the price range across shops.

Sources

General information only, not medical advice.