AHAs and BHAs: A Guide to Chemical Exfoliants
What AHAs and BHAs are
AHAs and BHAs are chemical exfoliants. Instead of scrubbing, they loosen the bonds between dead skin cells so the surface renews more evenly. Used well, they smooth texture, brighten tone and keep pores clear, with less risk of the micro damage that harsh scrubs can cause.
Chemical exfoliants sound intimidating, but they are often gentler and more even than physical scrubs when used correctly. Instead of rubbing away at the surface, they work chemically to loosen dead cells, which gives a smoother result with less risk of micro tears. The skill is in choosing the right acid for your skin and using it at a sensible frequency.
AHAs: surface and tone
Alpha hydroxy acids are water soluble and work on the surface of the skin. Common ones include glycolic, lactic and mandelic acid.
- Glycolic acid. Small molecule, strong on texture and tone.
- Lactic acid. Gentler, with a hydrating feel, good for drier or sensitive skin.
- Mandelic acid. Larger molecule, gentle, often a good choice for deeper skin because it is less likely to irritate.
AHAs suit dullness, uneven tone and rough texture.
BHAs: oil and pores
Beta hydroxy acid, meaning salicylic acid, is oil soluble, so it can get into pores and clear the oil and debris inside them. That makes it a strong choice for oily and acne prone skin, blackheads and congestion.
It also has a calming quality, which suits inflamed, breakout prone skin. See the acne routine.
How to use them safely
- Start once or twice a week and build up as your skin tolerates.
- Do not layer several exfoliants at once, and go easy if you also use retinol.
- Wear broad spectrum SPF, since exfoliants can increase sun sensitivity.
- If skin becomes tight, shiny or stings, you are overdoing it. Scale back and repair the barrier.
Signs you are over exfoliating
More exfoliation is not better. Overdoing it damages the skin and undoes the benefits. Watch for warning signs: tightness, a shine that reads as sensitivity rather than oil, stinging when you apply products, redness and unexpected breakouts.
If you notice these, stop exfoliating and focus on repair with gentle cleansing, moisture and barrier support. Once the skin recovers, reintroduce acids at a lower frequency. For most people, exfoliating one to three times a week is plenty, and daily use is rarely needed.
Which one to choose
Choose an AHA for dullness, uneven tone and rough texture, and a BHA for oiliness, congestion and breakouts. Combination skin can use both, applied to the right zones. If you have deeper skin, gentler acids like lactic and mandelic reduce the risk of irritation and dark marks. A skin scan can help you decide what your skin actually needs. Try the scan.
Frequently asked
AHAs are water soluble acids like glycolic and lactic acid that exfoliate the surface of the skin to improve tone and texture. BHA is salicylic acid, which is oil soluble and gets into pores to clear oil and debris, making it better for oily and acne prone skin.
BHA, meaning salicylic acid, is usually better for acne because it is oil soluble and can clear the inside of pores. It suits oily skin, blackheads and congestion. AHAs are more useful for surface texture and uneven tone.
Start using AHAs or BHAs once or twice a week and build up gradually as your skin tolerates them. Avoid layering several exfoliants at once, and always wear broad spectrum SPF, since exfoliation can increase sun sensitivity.
Yes, when used carefully. Gentler acids like lactic and mandelic acid are often a good choice for deeper skin because they are less likely to cause irritation, which can lead to dark marks. Start slowly and wear daily sunscreen.
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