Ingredients
Acid exfoliation for beginners: the difference between AHA, BHA and PHA
What's the difference between AHA, BHA and PHA acids, which one suits your skin, and how many times a week? A simple guide to chemical exfoliation without irritation.
4 November 20266 min read
Exfoliation removes the dead cells that build up on the surface of your skin, so it becomes smoother and brighter, and the products you use after it absorb better. Korean skincare relies more on exfoliating with acids than on gritty scrubs, because the dose is clearer and there's less rubbing. But acids come in three families, and each one has its own job.
AHA: for the surface and radiance
Alpha hydroxy acids, the best known being glycolic and lactic acid, dissolve in water and work on the surface of the skin. They suit dull skin, rough texture and small whiteheads. COSRX AHA 7 Liquid is a well-known example, at a 7% concentration.
BHA: for pores and oil
Beta hydroxy acid, the best known being salicylic acid, dissolves in oil, so it can get into pores and clean out the oil inside them. That's what makes it the first choice for oily skin and blackheads. Anua BHA 2% Toner is a good place to start.
PHA: for sensitive skin
Polyhydroxy acids have larger molecules, so they penetrate more slowly and are gentler. They suit sensitive skin, or skin that tried AHA and wasn't comfortable with it. AXIS-Y PHA Peel is one of the gentle options.
Start with one acid, twice a week, at night. After that, decide whether to do more or not.
How to start without irritation
- Night only: make it an evening step after cleansing.
- Twice a week: and if your skin is comfortable after two weeks, increase it to three.
- One acid at a time: don't combine AHA and BHA from two different products at first. Some products combine them at a carefully chosen concentration, like Beauty of Joseon Green Plum Toner, and that's a different thing.
- Don't use it with retinol on the same night if you're a beginner.
- Sunscreen every morning, no exceptions: exfoliation makes skin more sensitive to the sun.
Signs you've overdone it
A light tingle in the first few seconds is normal with some acids. But lasting redness, a tight shine as if your skin were plastic, or visible peeling are signs that your skin barrier is worn out. Stop the acids for a week, focus on a gentle moisturizer and a centella product, then come back to them less often.
If you're pregnant or breastfeeding, ask your doctor before using salicylic products at high concentrations or every day.
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