AHA vs BHA: Choosing a Chemical Exfoliant for Acne-Prone Skin

Exfoliation removes the build-up of dead skin cells that can dull the skin and contribute to clogged pores. For acne-prone skin, dermatologists generally prefer chemical exfoliants over gritty scrubs, because they work evenly without tearing inflamed skin. The two main families are AHAs and BHAs. Here is how they differ and how to choose.

What is a chemical exfoliant?

Chemical exfoliants are acids that loosen the bonds holding dead skin cells together, so they shed more easily. They come in cleansers, toners, serums, pads and peels, at strengths suitable for home use.

AHAs: alpha hydroxy acids

AHAs are water-soluble acids that work mainly on the surface of the skin. Common examples include:

Glycolic acid: the smallest AHA, so it penetrates well and works quickly, but it can be more irritating.
Lactic acid: gentler and somewhat hydrating, often better for sensitive or dry skin.
Mandelic acid: a larger molecule that penetrates slowly, making it one of the gentlest options, and it is often used for acne-prone and darker skin tones.

Best for: rough texture, dullness, uneven tone and the dark marks left after spots.

BHAs: beta hydroxy acids

The main BHA in skincare is salicylic acid. Unlike AHAs, it is oil-soluble, which means it can travel into the pore and dissolve the mix of oil and dead skin that forms blackheads and whiteheads. It also has mild anti-inflammatory effects.

Best for: oily skin, blackheads, whiteheads, visible pores and mild acne. Our article on salicylic acid vs benzoyl peroxide covers it in more depth.

Which should you choose?

Mostly blackheads, whiteheads and oiliness: start with a BHA.
Mostly dark marks, dullness and rough texture: an AHA, especially mandelic or lactic acid, may suit you better.
Sensitive skin: start with a low-strength mandelic acid, lactic acid or salicylic acid product used twice a week.
Both concerns: some products combine AHAs and BHAs, but start slowly with these, as combinations are stronger.

How to use exfoliants safely

Start low and slow: use two or three times a week at first, then increase if your skin is comfortable.
Apply to clean, dry skin, usually in the evening.
Follow with moisturiser to support the skin barrier.
Wear sunscreen every morning: AHAs in particular increase sun sensitivity.
One exfoliant at a time: avoid layering several acids, scrubs and retinoids on the same night.

Using exfoliants with retinoids and benzoyl peroxide

Retinoids already speed up skin cell turnover, so combining them with frequent acids can lead to over-exfoliation. A common approach is to alternate nights: retinoid on some evenings, exfoliant on others, with plain moisturiser nights in between if needed. If you use benzoyl peroxide and a BHA together, watch for dryness. See our skincare routine guide for sample schedules.

Signs of over-exfoliation

Stinging when you apply products that normally feel fine.
Redness, tightness, a shiny or “plastic” look to the skin.
Flaking, rough patches or new breakouts of small bumps.

If you notice these, stop all acids and retinoids for a week or two and use only a gentle cleanser, moisturiser and sunscreen until your skin recovers.

What about scrubs?

Physical scrubs with rough particles can irritate inflamed acne and spread redness. If you like a physical exfoliant, use a very gentle one on areas without active spots, and not on the same day as acids.

Professional peels

Stronger peels performed by a dermatologist or trained professional can help with persistent acne and marks. They should not be attempted at home with high-strength products.

The bottom line

BHAs like salicylic acid are best for clogged pores and oily skin, while AHAs are better for texture and dark marks. Start gently, use one exfoliant at a time and always protect your skin with moisturiser and sunscreen.