AHA vs BHA vs PHA: Which Exfoliating Acid Suits Your Skin?

AHAs (like glycolic acid) improve skin texture, but they make skin burn more easily in the sun [2][3]. Salicylic acid (BHA) has a modest, conditionally recommended benefit for acne [4]. PHAs are gentler, with similar benefits to AHAs in one industry trial [5]. None of them 'shrinks pores'.

AHA — water-soluble surface exfoliants: Glycolic Acid, Lactic Acid, Mandelic Acid.

BHA — oil-soluble, works into pores: Salicylic Acid, Betaine Salicylate. Willow bark extract is not the same thing.

PHA — larger, gentler molecules: Gluconolactone, Lactobionic Acid.

AHAs and texture. Six months of 25% AHA lotion thickened sun-damaged skin by about a quarter and increased collagen density in a pilot study [1] — but that is far stronger than face products.

AHAs and the sun. In a double-blind trial, four weeks of 10% glycolic acid lowered the dose of UV needed to burn skin and increased sunburn cells; the effect wore off a week after stopping [2]. A second study found 10% glycolic acid increased UV redness and DNA damage, while 2% salicylic acid did not [3]. The US FDA recommends AHA products carry a sunburn warning and advises sun protection during use and for a week after [6].

Salicylic acid and acne. The American Academy of Dermatology's 2024 acne guideline gives salicylic acid only a conditional recommendation [4].

PHA. Over 12 weeks a PHA routine gave anti-ageing benefits similar to a glycolic acid routine, with less stinging, in an industry-run study [5].

Dull, rough skin: AHA, with daily sunscreen. Oily or acne-prone skin: BHA. Sensitive skin: PHA. Start two or three times a week, do not stack several acids at once, and avoid them on irritated skin.

The products below contain exfoliating acids and are compared daily across UK retailers, delivery included.