Can I use AHA and BHA together?

Yes — many products combine them. Start gradually and monitor for irritation. Alternate-night use of separate AHA and BHA products is also a common pattern.

What's the difference between glycolic acid and lactic acid?

Glycolic acid has the smallest molecule of the AHAs — most penetrative, most powerful, also most irritating. Lactic acid is gentler and has hydration benefits in addition to exfoliation. Mandelic acid is the gentlest AHA, suitable for sensitive skin.

Can I use AHA/BHA every day?

Lower concentrations (0.5%–2% BHA, 5% glycolic acid) can be used daily by tolerant users. Higher concentrations (10%+ AHA, 2% BHA leave-on) are typically used 2–4 times per week.

Are AHAs safe in pregnancy?

Lactic acid is generally considered safe. Glycolic acid is widely used during pregnancy at lower concentrations. Salicylic acid (BHA) at higher concentrations should be paused. Always confirm with your doctor.

AHA + BHA in skincare.

Alpha-hydroxy acids (AHAs) and beta-hydroxy acids (BHAs) are two categories of chemical exfoliants. AHAs (glycolic acid, lactic acid, mandelic acid) are water-soluble and exfoliate the skin's surface. BHAs (salicylic acid is the dominant member) are oil-soluble and penetrate the pore. Both work by dissolving the bonds that hold dead skin cells together, allowing them to shed naturally.

What it does

AHAs exfoliate the surface — improving texture, tone, hyperpigmentation, and sun damage. BHAs penetrate the pore — clearing congestion, treating acne, and reducing pore appearance. Many products combine both for complete chemical exfoliation across surface and pore.

The evidence

Strong for both categories. AHAs and BHAs are the standard topical chemical exfoliants in dermatology, with multi-decade clinical research support.

Who should use it

AHAs: dull, dry, sun-damaged, or hyperpigmented skin. BHAs: oily, congested, or acne-prone skin. Combination products: anyone wanting both surface and pore exfoliation. Avoid concurrent use with retinol — alternate nights or AM/PM split.

What it pairs with

Niacinamide and hyaluronic acid (offset potential dryness). Sunscreen (essential — chemical exfoliation increases photosensitivity). Avoid pairing with retinol or vitamin C in the same routine.

What to buy in Australia

Paula's Choice 2% BHA Liquid Exfoliant — AU$45, the cult BHA. The Ordinary Glycolic Acid 7% Toning Solution — AU$15, the affordable AHA toner. Some By Mi AHA-BHA-PHA 30 Days Miracle Toner — AU$28, the K-beauty triple-acid combination toner.

Frequently asked questions.

Can I use AHA and BHA together?: Yes — many products combine them. Start gradually and monitor for irritation. Alternate-night use of separate AHA and BHA products is also a common pattern.
What's the difference between glycolic acid and lactic acid?: Glycolic acid has the smallest molecule of the AHAs — most penetrative, most powerful, also most irritating. Lactic acid is gentler and has hydration benefits in addition to exfoliation. Mandelic acid is the gentlest AHA, suitable for sensitive skin.
Can I use AHA/BHA every day?: Lower concentrations (0.5%–2% BHA, 5% glycolic acid) can be used daily by tolerant users. Higher concentrations (10%+ AHA, 2% BHA leave-on) are typically used 2–4 times per week.
Are AHAs safe in pregnancy?: Lactic acid is generally considered safe. Glycolic acid is widely used during pregnancy at lower concentrations. Salicylic acid (BHA) at higher concentrations should be paused. Always confirm with your doctor.