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AHA, BHA and PHA acids: pH, levels and the legal limits per market

How glycolic, lactic and mandelic acid, salicylic acid, gluconolactone and lactobionic acid work, why pH matters as much as percentage, what the FDA, EU, Canada, Korea and China require, and when an exfoliating product becomes an acne drug.

Not legal adviceThis guide summarizes published rules and studies as of October 2026. Your safety assessor, importer or the regulator has the final word for your product and market.

Short answer

For consumer AHA products in the US, the CIR expert panel judged glycolic and lactic acid safe at 10% or less and pH 3.5 or higher, and FDA recommends a "Sunburn Alert" label. Canada allows 3% to 18% AHA (including PHAs) at pH 3.5 or higher with set warnings, while the EU has no AHA limit in law. Salicylic acid (BHA) is capped in the EU at 2% in most products, 3% in rinse-off hair products and 0.5% in body lotion, never in products for children under 3, and Canada caps it at 2%. In the US, salicylic acid 0.5% to 2% with an acne claim is an OTC acne drug, and in Korea leave-on products may only use it up to 0.5%.

AHA, BHA and PHA: the differences

All three are hydroxy acids that loosen the bonds between dead cells on the skin surface, so they shed faster and skin looks smoother. They differ in size and in where they dissolve.

Acid	INCI	Group	Key traits
Glycolic acid	Glycolic Acid	AHA	Smallest AHA, penetrates fastest, most studied, most irritating
Lactic acid	Lactic Acid	AHA	Slightly larger, also a humectant, common in body care
Mandelic acid	Mandelic Acid	AHA	Larger molecule, slower and often gentler; fewer studies
Salicylic acid	Salicylic Acid	BHA	Oil soluble, so it works inside oily pores; anti-inflammatory; an OTC acne drug in the US
Gluconolactone	Gluconolactone	PHA	Large, slow, humectant and antioxidant; turns into gluconic acid in water
Lactobionic acid	Lactobionic Acid	PHA (bionic acid)	Large sugar-acid, humectant and antioxidant

K-beauty labels also use "BHA" for salicylic acid derivatives and plant sources such as betaine salicylate or willow bark extract. Those are different INCI names with their own rules; do not call them salicylic acid on the box.

What they do and the evidence

AHAs: reviews describe exfoliation, smoother texture, a brighter look, and at higher strengths, use in peels for photoaging, acne and pigment (Kornhauser 2010). Effects depend on concentration and pH; a 2018 review concludes that whether AHAs help or harm skin depends on concentration (Tang 2018). Evidence level: good for exfoliation and texture.
Sun sensitivity: in FDA-reviewed studies, 10% glycolic acid at pH 3.5 applied daily for 4 weeks made skin significantly more sensitive to UVB, and sensitivity returned to normal 1 week after stopping, as summarized in the EU SCCNFP position paper on AHAs.
Salicylic acid: recognized by FDA as an effective OTC acne active at 0.5% to 2%. A 2020 Cochrane review of topical acne treatments rated the trial evidence for salicylic acid as low quality, so the drug status rests on the monograph, not on large modern trials.
PHAs: a review by the researchers who developed them reports AHA-like smoothing with less stinging, plus humectant and antioxidant effects, and use on sensitive skin (Grimes 2004). Evidence level: moderate, much of it from the developers.

pH and free acid: why the label percentage is not enough

An acid only exfoliates in its free (un-ionized) form. How much of it is free depends on the product's pH compared with the acid's pKa, the pH at which half of it is free. Glycolic and lactic acid have a pKa of about 3.8; salicylic acid about 3.0.

Product pH	Share of glycolic acid in free form (pKa about 3.8)	What it means
3.5	About 67%	Strong exfoliation; the lowest pH CIR accepted for consumer AHA products
3.8	About 50%	Strong; the pH the EU SCCNFP paper used for its glycolic suggestion
4.3	About 24%	Moderate, gentler
4.8	About 9%	Mild; mostly a buffered, low-irritation product

The percentages come from the standard Henderson-Hasselbalch equation. So "10% glycolic acid at pH 4.8" may exfoliate less than "5% at pH 3.6". The SCCNFP paper notes that pH was the most important factor in AHA irritation, more than concentration, and that other formula factors also matter. Always state both the acid percentage and the pH in your specification, and check how your market calculates its limit (Canada uses "mono-AHA equivalents").

Typical levels

Product type	Common range	Where the number comes from
Daily AHA toner or serum (consumer)	Up to 10% at pH 3.5 or higher	CIR safety conclusion cited by FDA
Professional (salon) AHA peel	Up to 30% at pH 3.0 or higher, brief use, rinsed, applied by trained staff	CIR salon conclusion
EU precautionary suggestion (not law)	Glycolic up to 4% at pH 3.8 or higher; lactic up to 2.5% at pH 5 or higher	SCCNFP position paper, 2000
Canada consumer AHA (includes PHAs)	3% to 18% at pH 3.5 or higher	Health Canada Hotlist
Salicylic acid, leave-on face (US acne drug)	0.5% to 2%	21 CFR 333.310 (OTC monograph M006)
Salicylic acid, EU	2% most products, 3% rinse-off hair, 0.5% body lotion	Annex III entry 98

ExampleA 150 mL daily exfoliating toner for the US, Canada and the EU: 5% glycolic acid at pH 3.8 with 0.5% salicylic acid and gluconolactone. US: under the CIR 10% and pH 3.5 conditions, with the FDA Sunburn Alert text. Canada: inside 3% to 18% at pH 3.5 or higher, with the Hotlist warnings in English and French. EU: no AHA limit in law, but the safety assessor will look at the 4% glycolic suggestion and may ask for tolerance data; salicylic acid is under the 2% cap. No acne claims, so it stays a cosmetic.

United States: FDA and the acne monograph

AHA safety conditions
FDA's AHA page cites the CIR panel: products with glycolic and lactic acid are safe for consumers at 10% or less, pH 3.5 or higher, if formulated to protect against sun sensitivity or labeled to use daily sun protection. These are expert conclusions FDA points to, not a numeric FDA regulation.
Sunburn Alert labeling
FDA's 2005 guidance recommends that AHA cosmetics carry: "Sunburn Alert: This product contains an alpha hydroxy acid (AHA) that may increase your skin's sensitivity to the sun and particularly the possibility of sunburn. Use a sunscreen, wear protective clothing, and limit sun exposure while using this product and for a week afterwards."
Acne claims make it a drug
Salicylic acid 0.5% to 2%, benzoyl peroxide 2.5% to 10% and sulfur 3% to 10% are the acne actives in 21 CFR 333.310. A product that claims to treat acne must follow the monograph: Drug Facts label, drug GMP and drug establishment registration. FDA also says products sold to treat acne, remove scars or lighten skin are drugs.
Skin peelers
FDA notes that some high-strength "skin peeler" products are marketed with therapeutic claims; those claims also make them drugs.

See our cosmetic vs drug guide and MoCRA guide for the US cosmetic duties.

EU and UK rules

Ingredient	EU rule
Glycolic, lactic, mandelic acid, PHAs	No Annex III entry; the safety assessor judges level and pH in the CPSR, often with the SCCNFP suggestion in mind
Salicylic acid as an active (Annex III entry 98, replaced by Regulation (EU) 2021/850)	(a) Rinse-off hair products 3.0%; (b) other products 2.0%, except (c) body lotion, eye shadow, mascara, eyeliner, lipstick and roll-on deodorant 0.5%. These levels include any preservative use
Salicylic acid conditions	Not in preparations for children under 3; not where it can be inhaled; not in oral products. Label "Not to be used for children under 3 years of age" on products that might be used for children under 3
Salicylic acid as a preservative (Annex V entry 3)	0.5% (as acid)
Benzoyl peroxide	Allowed only in professional artificial nail systems (Annex III entry 94); acne products with it are medicines

Salicylic acid is classified as a category 2 reproductive toxicant (CMR 2) under EU chemical law, and it stays allowed only because the SCCS assessed it as safe under these conditions (Regulation (EU) 2019/1966). The UK has its own lists since Brexit; check them with your UK Responsible Person. More in our EU guide and UK guide.

Canada, Korea and China

Market	AHA and PHA	Salicylic acid
Canada (Hotlist, page dated 13 August 2025)	The entry covers AHAs, "including polyhydroxy acids and bionic acids" such as gluconolactone and lactobionic acid. Consumer skin products: 3% to 18% total mono-AHA equivalents at pH 3.5 or higher, with pH data on request. Professional: 18% to 30% and/or pH 3.0 to 3.5, with safety evidence. Warnings in English and French, including "Use only as directed", "Avoid contact with the eyes" and the sunscreen advice	2% maximum. Acne treatment claims make it a drug or natural health product
Korea	Products with more than 0.5% AHA must say to use sunscreen (leave-on), to test on a small area, and, above 10% AHA or below pH 3.5, to consult a specialist	Up to 0.5% as a preservative, not in products labeled for babies or children aged 13 or under (shampoo excepted). Higher levels only as a functional cosmetic active: 2% in body and face cleansers, 3% in rinse-off hair products. Acne functional report route: 0.5% salicylic acid in rinse-off cleansers only. Label: "Do not use on children aged 3 or under" (except rinse-off products such as shampoo)
China (as reported by the Hong Kong Consumer Council, 2025)	Total AHA no more than 6%, pH not lower than 3.5	2% maximum

The Korean salicylic acid rule surprises many founders: a leave-on BHA serum or toner made for Korea stays at 0.5% or below. For export markets the same factory can make a 2% version if the target market allows it. See our Korea, Canada and China guides.

Formulation, stability and packaging

Buffering: chemists partly neutralize acids (often with sodium hydroxide or an amino acid) to set the pH. Record the final pH range in the specification and check it in every batch COA.
pH drift: pH can move during storage, which changes both strength and irritation. Track it in the stability study; see our stability testing guide.
Preservation: low pH helps, but acid products still need a working preservative system and a challenge test (ISO 11930).
Packaging: acids can attack some metals and printed decorations. Use plastics and closures tested with the formula; pads in jars need a tight seal so they do not dry out. See our packaging options.
Salicylic acid solubility: it dissolves poorly in water, so it needs solvents such as glycols or a neutralized form; crystals in a cold warehouse are a classic stability failure.

Pairing, conflicts and who should avoid acids

Pair with	Use care with	Who should avoid or ask a doctor
Panthenol, allantoin, centella, ceramides (comfort); niacinamide and zinc PCA (oily skin); hyaluronic acid	Retinoids, vitamin C at low pH and benzoyl peroxide in the same routine step; physical scrubs	People with very sensitive skin, eczema or rosacea; anyone after peels, laser or waxing; children under 3 for salicylic acid; people allergic to aspirin (salicylates) for salicylic acid; pregnancy for high-strength salicylic acid peels

For pregnancy wording, see our pregnancy-safe formulating guide.

Claims

Usually fine as a cosmetic	Drug or regulated claim
"Exfoliates for smoother-looking skin", "refines the look of pores"	"Treats acne", "clears breakouts", "prevents pimples" (US OTC acne drug; Canada drug or NHP)
"Helps skin look clearer" (careful: some reviewers read it as acne)	"Removes scars", "treats keratosis pilaris"
"Brightens the look of dull skin"	"Lightens dark spots" (US skin lightener, a drug)
Korea, after an acne functional report on a rinse-off cleanser: "helps relieve acne-prone skin"	The same wording on a leave-on product in Korea

Common mistakes

Specifying only "10% glycolic acid" without a pH range, then getting a batch at pH 3.0 that burns.
Leaving off the FDA Sunburn Alert on a US AHA product, or the Hotlist warnings in both English and French in Canada.
Calling a salicylic acid toner "acne treatment" in the US without following the OTC acne monograph and Drug Facts rules.
Selling a 2% salicylic acid body lotion in the EU, where body lotion is capped at 0.5%.
Making a leave-on 2% BHA serum for the Korean market, where leave-on salicylic acid stays at 0.5%.
Forgetting "Not to be used for children under 3 years of age" on EU salicylic acid products that children could use.
Counting gluconolactone as "not an AHA" in Canada; the Hotlist entry includes PHAs and bionic acids.

Checklist for an exfoliating product

Acid or acids chosen by INCI name, with percentage and final pH range in the specification.
Free-acid strength understood (pH vs pKa), not only the percentage.
US: CIR conditions met (10% or less, pH 3.5 or higher for consumer use) and Sunburn Alert text on the label.
EU: salicylic acid under 2% (0.5% in body lotion, 3% in rinse-off hair) and the under-3 warning where needed.
Canada: AHA level and pH inside the Hotlist range, bilingual warnings, salicylic acid 2% or less.
Korea: AHA caution statements; leave-on salicylic acid at 0.5% or less.
No acne, scar or lightening claims unless you follow the drug route.
Stability study tracks pH, appearance and crystal formation.
Challenge test passed.
Directions: frequency, patch test, sunscreen, avoid eyes and broken skin.

How KoreanOEM helps

Our formula library has ready exfoliating formulas that our chemists set to the right pH for your markets:

AHA, BHA and PHA toner (glycolic acid 5%, salicylic acid 0.5%, gluconolactone), BHA serum, BHA toner pads, PHA and heartleaf toner pads, and BHA and tea tree spot gels.
AHA (lactic acid) and PHA peeling gels, BHA gel and foam cleansers, a BHA body wash, a BHA scalp scaler, a sugar and AHA body scrub and a urea and AHA body cream.
A toner starts from about USD 2.89 per unit at 1,000 units; a serum from about USD 3.40 at 500 units.
Our label proof check covers the FDA Sunburn Alert, the EU under-3 warning, Canada's bilingual Hotlist warnings and Korean cautions before printing. A challenge test (ISO 11930) is from USD 1,000 per formula.
Want an OTC acne drug product for the US? That is quoted case by case; tell us and our team checks before anything is promised.

Get a free quote Order a sample box

Frequently asked questions

What pH should an AHA toner have?

For US consumer products, the CIR expert panel judged glycolic and lactic acid safe at pH 3.5 or higher and 10% or less, and Canada requires pH 3.5 or higher for consumer AHA products. Most daily toners sit between about pH 3.5 and 4.5, where a useful share of the acid is still in its active free form.

Is there an EU limit for glycolic acid?

There is no Annex III limit for glycolic, lactic or mandelic acid in EU law. A 2000 SCCNFP position paper suggested, as a precaution, glycolic acid up to 4% at pH 3.8 or higher and lactic acid up to 2.5% at pH 5 or higher, and safety assessors take it into account.

What is the maximum salicylic acid in EU cosmetics?

Under Annex III entry 98, 2% in most products, 3% in rinse-off hair products and 0.5% in body lotion, eye shadow, mascara, eyeliner, lipstick and roll-on deodorant, including any preservative use. It must not be used in products for children under 3.

Is a salicylic acid toner a drug in the US?

Only if it makes acne claims. Salicylic acid 0.5% to 2% is an OTC acne active, and a product claiming to treat acne must follow the acne monograph with a Drug Facts label; with claims such as "exfoliates" or "refines the look of pores" it stays a cosmetic.

Do I need the Sunburn Alert on AHA products?

FDA recommends it for cosmetics with AHAs applied to skin or lips in its 2005 labeling guidance, and most US brands use the exact FDA wording. Canada requires its own Hotlist warnings in English and French for AHA products above 3%.

Are PHAs gentler than AHAs?

PHAs such as gluconolactone and lactobionic acid are larger molecules that reviews report as less stinging, with added humectant and antioxidant effects. In Canada they still fall under the Hotlist AHA entry.

How much salicylic acid can a leave-on product contain in Korea?

Up to 0.5%, the preservative level. Korea allows higher salicylic acid only as a functional cosmetic active in rinse-off products: 2% in body and face cleansers and 3% in rinse-off hair products.

Can I use AHA and retinol together?

Both raise irritation and sun sensitivity, so most brands put them in separate products and suggest using them on different nights, with daily sunscreen.

Sources

Checked against these sources in October 2026. Rules and fees change; check with the authority or your importer before you sell.