Glossary
AHA, BHA and PHA
Three families of chemical exfoliant. The difference is what they dissolve in and how fast they work.
All three loosen the bonds between dead surface cells so they shed more evenly. They differ in solubility and in speed.
AHA — alpha hydroxy acids, mainly glycolic and lactic acid. Water-soluble, so they work on the surface. Best for dullness, rough texture and sun-driven pigmentation. Glycolic is the smallest and strongest; lactic is gentler and also hydrating. Typical strengths 5% to 10%, once or twice a week.
BHA — salicylic acid. Oil-soluble, so it can get inside a pore rather than only working on top. Best for blackheads, congestion and oily skin. Typical strength 2%, two or three nights a week.
PHA — polyhydroxy acids, mainly gluconolactone and lactobionic acid. Larger molecules, so they penetrate less and work more slowly and gently. The sensible first exfoliant for reactive skin.
Two rules matter more than the choice: never on the same night as a retinoid, and never alongside a scrub. If skin stings or flakes, you are exfoliating too often — the fix is frequency, not a gentler acid.
Sunscreen is not optional while using any of them.
See also
This article is general information, not medical advice. Skincare products are not medicines. Speak to a dermatologist about persistent or worsening skin conditions.