AHA, BHA and PHA: Which Acid Does What?

Rough patches, blackheads that won't budge, skin that looks a bit grey. There's an acid for each of those, and they're not interchangeable.

What are AHA, BHA and PHA?

Exfoliating acids loosen the build-up of dead skin cells. AHAs (glycolic, lactic, mandelic acid) work on the surface for smoothness and glow. BHA (salicylic acid, or LHA and betaine salicylate) is oil-loving, so it works inside pores. PHA (gluconolactone) is the gentlest, with bigger molecules that also hydrate.

What they do for your skin

• Smoother texture. AHAs and PHAs smooth rough, bumpy skin.
• Clearer-looking pores. BHA helps clear the gunk inside pores that turns into blackheads.
• Fresher, brighter look. Regular gentle exfoliation helps dull skin look more radiant.

Who it suits

AHA for dull or rough skin, BHA for oily and blackhead-prone skin, PHA for sensitive skin. Skip acids on broken or sunburnt skin.

Skin MBTI match: O (oily) · P (tone care). Not sure of yours? The Skin MBTI quiz tells you in three minutes.

How to use it

1. Start two or three times a week, at night.
2. Use one acid product at a time while your skin adjusts.
3. Wear sunscreen every day. Exfoliated skin is more sun-sensitive.

When you'll notice it: Skin feels smoother after the first few uses. Pores look clearer over three to four weeks.

Good to know: Pregnant or breastfeeding? Check with your doctor before using salicylic acid. Keep acids away from the eye area.

What to pair it with

Follow acids with a soothing, hydrating step like panthenol, cica or ceramides. Use retinol on alternate nights rather than the same night.

Myth vs fact

Myth: If it tingles, it's working better.
Fact: A little tingle can happen, but burning or redness means the acid is too strong or you're using it too often.

How to choose one

• On labels: Glycolic, Lactic or Mandelic Acid (AHA). Salicylic Acid, Betaine Salicylate or LHA (BHA). Gluconolactone or Lactobionic Acid (PHA).
• Pads and toners are the easiest start. Leave-on serums are stronger than wash-off cleansers.
• Start with one acid product, not three.

Where to find it

KIWIGLOW's lotus pads combine AHA, BHA and PHA for a gentle daily swipe, and Baegayul's toner uses mild PHA. From the big names, Medicube's Zero Pore Pads come in a classic AHA+BHA and a gentler PHA version. 23YEARSOLD's Badecasil (glycolic acid plus betaine salicylate) and KAINE's 9% lactic acid night serum are two more to try.

See more in our AHA BHA Reset collection.

FAQ

Can I use AHA and BHA together?

Yes, if your skin tolerates it. Many pads already combine them. Start slowly.

Which acid is best for sensitive skin?

PHA is the gentlest. Mandelic acid (an AHA) is another softer choice.

How often should I exfoliate?

Two or three times a week is plenty for most people. Daily gentle pads are fine if your skin is happy.

Korean corner: 각질 (gak-jil) means "dead skin flakes (what acids help clear)".