AHA, BHA and PHA Explained: The Difference Between Exfoliating Acids
AHAs, BHAs and PHAs are three families of exfoliating acids used to loosen dead skin cells and support the look of smoother, brighter skin.
AHAs (alpha hydroxy acids)
Water-soluble acids such as glycolic and lactic acid, used on the surface of the skin for texture, dullness and uneven tone.
BHA (beta hydroxy acid)
Salicylic acid is oil-soluble, so it can work inside pores. It is commonly used for blocked pores and blemish-prone skin.
PHAs (polyhydroxy acids)
Larger molecules such as gluconolactone that exfoliate more gently, often chosen by people with sensitive skin.
How to use them
Start once or twice a week, at night, follow with moisturiser, and wear SPF daily because acids can increase sun sensitivity. Avoid stacking several exfoliating products. Patch test first, and speak to your GP or pharmacist before using salicylic acid if you are pregnant.
Shop exfoliating acids
Browse our AHA, BHA and PHA collection, or see scrubs, peels and exfoliators.
Exfoliating acids: frequently asked questions
Which exfoliating acid is best for sensitive skin?
PHAs are generally considered the gentlest, followed by lower-strength lactic acid. Start slowly and patch test.
Which acid is best for blocked pores?
BHA (salicylic acid) is commonly used for blocked pores because it is oil-soluble.
How often should I exfoliate?
Most people start once or twice a week and adjust based on how their skin responds.