Three families of acid doing three different jobs. Picking the wrong one is why so many people conclude exfoliation does not work for them.
By Sawyer V. · Published September 10, 2026 · Last updated September 10, 2026
The short answer
AHAs are water-soluble and work on surface texture and tone. BHA is oil-soluble and works inside the pore on congestion. PHAs are larger, gentler AHAs for reactive skin. Match the acid to the problem, not to the strongest number on the shelf.
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How We Picked
We ranked on published concentration and, where brands disclose it, pH — the two variables that actually determine potency. Then on whether the formula suits the buyer each acid type is right for. We have not tested any of these; the assessment is of published formulation data.
Everyone in this category says they tested twenty of these. We have not tested any, and we say so. What we did instead: compiled the published concentrations and ingredient lists, checked each claim against what the formula can actually support, and wrote down who each product is wrong for. The full method is published so you can check it.
Quick Picks
The short answer, by buyer. Select any row for the full write-up.
#
Product
Best for
Where to buy
1
No product photograph available for Paula's Choice Skin Perfecting 2% BHA Liquid Exfoliant
Paula's Choice Skin Perfecting 2% BHA Liquid ExfoliantIt publishes both variables that matter — concentration and pH — which almost nothing else in the category does.
No product photograph available for The Ordinary Glycolic Acid 7% Exfoliating Toner
The Ordinary Glycolic Acid 7% Exfoliating TonerA stated percentage at a price that lets you treat arms and legs as well as your face — and body skin is where AHAs do some of their most visible work, on keratosis pilaris and rough elbows..
No product photograph available for Naturium PHA Topical Acid 12%
Naturium PHA Topical Acid 12%PHAs are the correct answer when AHAs are too much rather than a reason to give up on exfoliation, and gluconolactone has the useful property of hydrating as well as exfoliating..
No product photograph available for Sunday Riley Good Genes Lactic Acid Treatment
Sunday Riley Good Genes Lactic Acid TreatmentLactic acid is the right substitution when glycolic is too much but PHA is too slow, and this is the most widely available well-formulated example of it..
No product photograph available for Dr. Dennis Gross Alpha Beta Universal Daily Peel
Dr. Dennis Gross Alpha Beta Universal Daily PeelDosing is where most people go wrong with exfoliants, and a pre-measured two-step pad removes that variable entirely.
#ad — buying through these links earns us a commission at no cost to you. No price is shown because we do not run a live price feed, and a remembered number would be a guess.
The same jobs as an AHA, more slowly, on reactive skin
The single most useful line here: if you can see the problem on the surface, use an AHA. If the problem is inside a pore, use a BHA. Nothing water-soluble reaches inside an oil-filled follicle, which is why glycolic acid disappoints on blackheads no matter how high the percentage goes.
The full head-to-head is in glycolic acid vs. salicylic acid. Within the AHAs, molecule size decides gentleness: glycolic is smallest and strongest, lactic is larger and hydrating, mandelic is largest and gentlest.
Percentage Is Half the Story; pH Is the Other Half
Two products can both say 10% glycolic acid and differ substantially in strength, because what determines potency is the free acid value — how much of the acid is unbuffered and active at the product's pH.
A 10% AHA at pH 4.5 can be gentler than a 7% at pH 3.4. Almost no brand publishes free acid value, and the ones that publish pH at all are already ahead of the field — which is why pH disclosure is a ranking criterion on this page.
The other variable nobody mentions: contact time. A 2% BHA in a cleanser rinsed after thirty seconds is a far smaller dose than 1% left on overnight. The dose is percentage multiplied by how long it stays on your face.
Using an Exfoliant Without Over-Doing It
Start twice a week, not daily. Frequency is built up, not assumed.
Apply to clean dry skin, before heavier serums and moisturizer, and give it a minute.
One acid at a time. Stacking an AHA and a BHA mostly adds irritation rather than a second effect.
Do not use it on the same night as a retinoid while either is new. Alternate — see the layering order guide.
Follow with a moisturizer. The dryness is a cost, not evidence it is working.
Wear sunscreen daily. Exfoliated skin left unprotected pigments more, not less.
Stop for a week at the first sign of shine, tightness or stinging on water.
Over-exfoliated skin looks shiny and feels tight, stings on water, and reacts to products it used to tolerate. The correct response is to stop all exfoliation for a week or two and use a ceramide moisturizer — not to switch to a gentler acid and continue.
No product photoNo product photograph available for Paula's Choice Skin Perfecting 2% BHA Liquid Exfoliant
Labeled 2% salicylic acid with the pH published in the low-to-mid 3s
Green tea extract as a soothing ingredient; fragrance-free
A 1% version exists for sensitive skin
It publishes both variables that matter — concentration and pH — which almost nothing else in the category does. That transparency is why it functions as the benchmark everything else gets measured against.
Who it’s not for
Dry or already-irritated skin, and anyone with a salicylate or aspirin sensitivity. A leave-on 2% at low pH is the strongest routine format of this ingredient; start at 1%.
No product photoNo product photograph available for The Ordinary Glycolic Acid 7% Exfoliating Toner
2 — Surface texture and tone, cheaply
The Ordinary Glycolic Acid 7% Exfoliating Toner
What’s in it
Labeled 7% glycolic acid in a leave-on toner
Tasmanian pepperberry and aloe as stated soothing agents
Large bottle, which makes body use practical too
A stated percentage at a price that lets you treat arms and legs as well as your face — and body skin is where AHAs do some of their most visible work, on keratosis pilaris and rough elbows.
Who it’s not for
Sensitive, dry or rosacea-prone skin, and anyone already using a retinoid most nights. This is an unbuffered 7% AHA and stacking it on a nightly retinoid is the classic route to over-exfoliation.
No product photoNo product photograph available for Naturium PHA Topical Acid 12%
3 — Reactive skin that cannot take an AHA
Naturium PHA Topical Acid 12%
What’s in it
Labeled 12% gluconolactone, a polyhydroxy acid
Larger molecule than glycolic or lactic acid, so it penetrates less
Fragrance-free; also functions as a humectant
PHAs are the correct answer when AHAs are too much rather than a reason to give up on exfoliation, and gluconolactone has the useful property of hydrating as well as exfoliating.
Who it’s not for
Anyone wanting fast results. The larger molecule is the whole point and it is also the limitation — this works more slowly than an equivalent AHA, by design.
No product photoNo product photograph available for Sunday Riley Good Genes Lactic Acid Treatment
Premium Beauty listing
4 — Lactic acid, the gentler AHA
Sunday Riley Good Genes Lactic Acid Treatment
What’s in it
Built on lactic acid, a larger AHA molecule than glycolic
Licorice and lemongrass extracts as stated supporting ingredients
Opaque bottle with a pump
Lactic acid is the right substitution when glycolic is too much but PHA is too slow, and this is the most widely available well-formulated example of it.
Who it’s not for
Anyone buying on price or wanting published numbers. This costs many times an equivalent drugstore lactic acid and the concentration is not stated.
No product photoNo product photograph available for Dr. Dennis Gross Alpha Beta Universal Daily Peel
Premium Beauty listing
5 — A pre-dosed format that removes the guesswork
Dr. Dennis Gross Alpha Beta Universal Daily Peel
What’s in it
Two-step pad system combining AHAs and BHA with a neutralizing second step
Pre-dosed single-use pads
Individually wrapped; widely available
Dosing is where most people go wrong with exfoliants, and a pre-measured two-step pad removes that variable entirely. The neutralizing step is a genuine safety feature rather than packaging theater.
Who it’s not for
Daily use, despite the name, and anyone with reactive skin. Combining AHAs and BHA every day is more turnover than most skin tolerates — see the Skip This entry below.
Pre-dosed acid pads are a genuinely good format and the word daily on the packet is the problem. They frequently combine two or three acids, and a soaked pad delivers considerably more product than you would pour out yourself — so the dose per use is high even before you multiply it by seven. The people who do best with these use them two or three times a week; the people who end up shiny, tight and reactive followed the instruction on the box. The same caution applies to any exfoliating toner used morning and night: if a product contains glycolic or salicylic acid it is an exfoliant, whatever the bottle calls it, and twice-daily use is how people over-exfoliate without ever realizing they were exfoliating twice.
Frequently Asked Questions
AHAs are water-soluble and work on the surface. BHA is oil-soluble and works inside the pore. PHAs are larger, gentler AHAs for reactive skin.
Salicylic acid, because it dissolves in oil and reaches inside the follicle. Nothing water-soluble gets there, so AHAs disappoint on congestion regardless of percentage.
Two to three times a week for most skin, built up from twice. Daily use at working strengths is the most common cause of over-exfoliation.
You can, and for most people it is unnecessary — the second acid adds irritation rather than a second effect. Use them on different areas or alternate nights.
Skin looks shiny and feels tight, stings on water, and reacts to products it used to tolerate. Stop all exfoliation for a week or two and use a ceramide moisturizer.
By Sawyer V.. An enthusiast who’s genuinely into this: I read the manufacturer documentation, compile the published percentages, and do the arithmetic. No lab coat.
What I don’t do: test products, accept free product, or accept payment for placement. I hold no clinical credential and don’t claim one. How we pick.
Published September 10, 2026 · Last updated September 10, 2026
