AHA vs BHA vs PHA: Which Exfoliant Suits Your Skin?

AHAs exfoliate the surface of your skin, so they suit dullness and rough texture. BHAs are oil-soluble and work inside pores, so they suit oily skin, blackheads and congestion. PHAs are larger, gentler molecules that suit sensitive or exfoliation-new skin. Most people only need one of them, used a few times a week, alongside daily sunscreen.

Exfoliating acids are some of the most useful ingredients in skincare, but the labels can be confusing. Here's how each one works, who it suits, and how to fit one into your routine without overdoing it.

AHA vs BHA vs PHA at a glance

  • AHA (alpha hydroxy acid): water-soluble, works on the skin's surface. Common examples are glycolic, lactic and mandelic acid. Best for dullness, uneven texture and whiteheads.
  • BHA (beta hydroxy acid): oil-soluble, so it can get into pores. The common examples are salicylic acid and betaine salicylate. Best for oily, combination and blemish-prone skin with blackheads.
  • PHA (polyhydroxy acid): a bigger molecule that works more slowly on the surface. Gluconolactone is the most common. Best for sensitive skin or first-time exfoliators.

AHA: for dull, rough-feeling skin

AHAs loosen the bonds between dead cells on the surface of your skin so they shed more evenly. The result is smoother-feeling, brighter-looking skin. Glycolic acid has the smallest molecule of the AHAs, which makes it the most active and the most likely to tingle.

Try: COSRX AHA 7 Whitehead Power Liquid uses 7% glycolic acid with apple fruit water and niacinamide to remove dead skin cells and whiteheads and improve texture. COSRX lists it for normal to oily, combination and blemish-prone skin, and notes it isn't for very sensitive skin.

BHA: for oily skin, blackheads and congestion

Because BHAs dissolve in oil, they can work inside the pore lining as well as on the surface. That's why they're the go-to for blackheads, excess oil and clogged pores, which are common in humid parts of Australia like Brisbane, Cairns and Darwin, and for everyone else as summer arrives.

Try:

  • COSRX BHA Blackhead Power Liquid contains 4% betaine salicylate, a gentle BHA, plus niacinamide and sodium hyaluronate. It's designed to exfoliate inside pores, reduce blackheads and control excess oil while keeping skin hydrated. COSRX lists it for oily, combination and acne-prone skin.
  • Anua BHA 2% Gentle Exfoliating Toner pairs 2% BHA with tea tree for gentle exfoliation and pore care. It's aimed at combination and oily skin.

For more on clearing congestion, see our guide on how to get rid of blackheads.

PHA: for sensitive or first-time exfoliators

PHAs have a larger molecular size, so they work more slowly at the surface. That's why they're often recommended for reactive skin or for anyone trying acids for the first time.

Try: AXIS-Y PHA Resurfacing Glow Peel is a 10% PHA peeling gel that removes dirt, impurities and excess sebum from pores. It's made with extracts from five fruits and vegetables, including cucumber, papaya and cica, to soothe and refresh.

What about AHA + BHA combinations?

Many Korean toners combine acids at low percentages for everyday maintenance rather than a strong peel. Two good examples:

Combinations are convenient, but they still count as exfoliation. Don't layer one with a separate acid serum on the same night.

Which exfoliant should you choose?

  • Oily or combination skin, blackheads, shiny T-zone: start with a BHA.
  • Normal skin that looks dull or feels rough: start with an AHA.
  • Sensitive, reactive or dry skin: start with a PHA or a low-strength combination toner.
  • Not sure: a gentle combination toner is an easy place to begin.

Browse everything in one place in our Korean exfoliators and exfoliating toners collections.

How to use an exfoliating acid safely

  1. Start slowly. Two to three evenings a week is plenty to begin with. Increase only if your skin stays comfortable.
  2. Apply to clean, dry skin. Use it after cleansing, then follow with hydrating and moisturising steps.
  3. One acid at a time. Don't stack an AHA toner, a BHA serum and a peeling pad in one routine.
  4. Keep acids and retinoids on separate nights. Many retinal products, including several we stock, specifically advise against layering with strong acids on the same night.
  5. Wear SPF every morning. In Australia's UV, daily broad-spectrum sunscreen is essential when you exfoliate regularly. Beauty of Joseon Relief Sun SPF50+ PA++++ is a lightweight, fragrance-free everyday option.
  6. Patch test first, especially with stronger formulas like 7% glycolic acid.

Signs you're over-exfoliating

Watch for stinging when you apply products that usually feel fine, tightness, redness, flaking, or a shiny, "plastic" look to your skin. If this happens, stop all acids for a week or two and focus on gentle cleansing, hydration and a barrier-supporting moisturiser. If irritation persists, or you're dealing with persistent acne or a skin condition, see your GP or dermatologist.

Wondering whether pre-soaked pads count? They do. Read Can you use Korean toner pads every day? for how to fit them in.

FAQ

Can I use AHA and BHA together?

Yes, in a formula designed to combine them, like a combination toner. Avoid layering separate strong AHA and BHA products in the same routine, as this raises the risk of irritation.

Should I use exfoliating acids in the morning or at night?

Most people use them at night. If you use one in the morning, follow it with sunscreen.

Which acid is best for blackheads?

BHA, because it's oil-soluble and can work inside pores. Betaine salicylate and salicylic acid are the common forms.

Is PHA weaker than AHA?

PHAs work more slowly because of their larger molecular size, which is why they're often chosen for sensitive skin. "Gentler" is a better way to think of it than "weaker".

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