AHAs, BHA and PHA: the difference in plain English
Three families of chemical exfoliants. Different sizes, different jobs, different tolerances. Here is how to pick.
AHAs work on the surface
Alpha-hydroxy acids like Glycolic and Lactic are small, water-soluble molecules. They loosen the glue between dead cells on the very top of the skin, which is why they brighten tone and smooth texture quickly. Glycolic is the smallest and fastest; Lactic is slightly larger and adds a hydrating benefit.
BHA works inside the pore
Salicylic Acid is a beta-hydroxy acid. It is oil-soluble, so it moves through sebum and works inside the pore, not just on the surface. This is why it is the go-to for congestion, blackheads and blind pimples.
PHA is the gentle option
Polyhydroxy acids like Gluconolactone are much larger molecules. They exfoliate slower and rarely sting. Good for sensitive skin, first-time acid users, or evenings after retinol.
How to choose
Surface dullness and rough texture: AHAs. Blackheads and congestion: BHA. Sensitive or recovering: PHA. Most well-formulated kits use a combination, at percentages tuned to work together without over-exfoliating.
AHA + BHA + PHA Kit
The resurfacing routine for texture, dullness and uneven tone