AHAs are acids for the surface of the skin: they exfoliate the top layer and even out tone and texture. They are often confused with BHA, but they work differently, and understanding the difference matters if you are to choose the right one.
AHAs (glycolic, lactic) are water-soluble and work on the surface — they renew the skin, even out tone and texture, and help with surface pigmentation. They are the counterpart to BHA, which cleans pores. Glycolic is stronger, lactic is gentler and hydrates. For a beginner — not every day, and always with sunscreen.
01What AHA is and how it differs from BHA
AHAs (alpha hydroxy acids) are water-soluble and work on the surface of the skin: they speed up renewal, exfoliate dead cells and help with surface pigmentation and texture. BHA (salicylic) is oil-soluble and works inside the pore. Hence the division of labour: BHA for pores and oily skin, AHA for tone and smoothness.
AHA or BHA
AHA (glycolic, lactic)
- Where it works
- On the surface of the skin
- For what
- Tone, texture, dullness, surface pigment
- For whom
- Normal, dry, with pigmentation
BHA (salicylic)
- Where it works
- Inside the pore
- For what
- Blackheads, pores, oily skin
- For whom
- Oily, acne-prone
02Glycolic or lactic
Among the AHAs there are two main ones. Glycolic is the smallest molecule, penetrates deeper and works more strongly (and irritates more). Lactic is larger, gentler and also hydrates a little, so it suits sensitive and dry skin better, and for starting out.
03How to introduce it
- Begin once or twice a week, in the evening; lactic is gentler for starting out.
- Do not combine straight away with retinol, BHA and vitamin C — too harsh.
- Cosmetic concentrations — up to ~10% at a pH above 3.5.
- AHAs increase sensitivity to the sun — sunscreen is essential.
- If stinging and redness appear — reduce the frequency.
04Common mistakes
- Every day from the first time. A path to an irritated barrier.
- AHA + retinol + vitamin C at once. Too many actives.
- Without sunscreen. Photosensitivity and new pigmentation.
- Expecting a "peel effect" from frequency. More often ≠ better; the barrier matters more.
05Common questions
AHA or BHA — which to choose?
For dullness, uneven tone and texture — AHA. For oily skin, congested pores and blackheads — BHA. Sometimes they are used on different days for different concerns.
Where should a beginner start?
With a low-concentration lactic acid once or twice a week in the evening, alongside hydration and essential sunscreen by day.
06What to try
Lactic acid
Gentler, and also hydrates.
Смотреть на YesStyle StrongerGlycolic acid
Deeper and more active; introduce carefully.
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The article's key points draw on peer-reviewed publications:
This material is educational and does not replace a consultation with a dermatologist.