Pick your acid by the problem, not by the percentage. Clogged pores and blackheads want salicylic acid (a BHA), because it is oil-soluble and gets inside the pore. Rough texture and dullness want an AHA — glycolic if your skin is robust, lactic if it is not, mandelic if it is genuinely reactive or prone to dark marks. Then use the lowest strength that gives you a result, two or three nights a week, and leave it alone.
The failure mode in this category is not choosing the wrong acid, it is using the right one too often. Exfoliating every night is how people arrive at a shiny, stinging, reactive face and conclude their skin has become sensitive. It has not; it has been over-exfoliated, and the fix is two weeks of doing nothing but cleanser, moisturizer and sunscreen. Our damaged skin barrier guide covers the recovery in detail.
Below, six products ranked on acid type, stated concentration, the pH and vehicle they sit in, and who each one is genuinely for. The full AHA-versus-BHA breakdown lives in AHA vs BHA — start there if you are not sure which family you need. Everything here is over the counter and everything here has a live, date-stamped price.
Choose the acid, then the strength
- Salicylic acid (BHA) — oil-soluble, so it works inside pores. The right answer for blackheads, closed comedones and oily congestion. 2% is the standard.
- Glycolic acid (AHA) — the smallest molecule, so the fastest and the harshest. Good for texture and dullness on robust skin. 5–10% for at-home use.
- Lactic acid (AHA) — larger molecule, slower, kinder, and a humectant in its own right. The best starting acid. 5% to begin, 10% later.
- Mandelic acid (AHA) — the largest common AHA molecule and the gentlest. The pick for reactive skin and for anyone prone to post-inflammatory marks. 10% is a normal at-home strength because the molecule size does the moderating.
We wrote a full guide to each of these: salicylic acid, glycolic acid, lactic acid and mandelic acid.
Frequency is the variable that matters
Start at twice a week, at night, on dry skin, and hold there for a month before you change anything. If your skin is comfortable, go to three nights. Very few people need more than that, and nobody needs a leave-on acid every night on top of a retinoid. The visible signs you have gone too far are a tight, shiny look, stinging when you apply anything at all, and new sensitivity to products you used happily last month.
Because it matters more than the acid you pick, we have given frequency its own page: how often should you exfoliate? has the schedule by acid and by skin type, the five products that secretly count as exfoliation, and the two-week reset if you have overdone it.
The sunscreen part is not optional
Every AHA increases sun sensitivity — measurably, for about a week after use. Exfoliating without daily sunscreen is a net negative for your skin: you are removing the top layer and then handing what is underneath straight to UV. If you are not going to wear SPF every morning, skip this category entirely and put the money into a sunscreen you will actually wear. That is not a throwaway line — it is the single highest-return swap on this whole site.
What not to stack
Do not use an acid on the same night as a retinoid unless you have spent months proving your skin tolerates it. Alternate nights instead. Benzoyl peroxide and acids on the same evening is another common route to a wrecked barrier. And if you are using a prescription retinoid, treat any leave-on acid as an addition to discuss with whoever prescribed it.
If you want a schedule rather than a rule of thumb for alternating the two, skin cycling is the four-night version — acid, retinoid, two recovery nights — and it is the simplest way we know of to keep both actives without stacking them. And if blackheads specifically are what sent you to this page, the blackheads method guide covers the whole approach, including the two popular techniques that make them worse.
One family on this page deserves its own ranking, because the products are hard to compare and most of them will not state a percentage. If the gentlest AHA is what you are after — reactive skin, deeper skin tones, or acne that glycolic acid makes worse — see the best mandelic acid serums, which ranks within that family rather than across all of them.
