Hair Dye Ingredients in EU Cosmetics: How Annex III Entries and the 2003 Safety Strategy Work

Hair dye substances are the most heavily documented ingredient class in the EU cosmetics annexes. Almost every entry carries a maximum concentration, a mandatory warning text and a set of use restrictions, because the European Commission has spent more than two decades pushing manufacturers to prove each substance's safety with a formal dossier. This article explains the mechanics of that process, how to read a hair dye entry in Annex III, and what happened to five named substances that formulators and regulatory staff commonly search for: 2-methylresorcinol, 4-amino-2-hydroxytoluene, 2-nitro-p-phenylenediamine, 1,2,4-trihydroxybenzene and Basic Orange 31.

The 2003 hair dye strategy: dossiers in, or the substance is out

Since 2003 the European Commission has run what it calls a global strategy for the safety assessment of hair dyes. The mechanics are simple: cosmetic manufacturers and their trade associations had to prepare toxicological dossiers for each hair dye substance already on the market and submit them to the Commission for a risk assessment by the Scientific Committee on Consumer Safety (SCCS, formerly the SCCNFP/SCCP). A substance with no dossier, or with a dossier that produced a negative SCCS opinion, was not left in limbo — it was moved to Annex II, the list of substances prohibited in cosmetic products.

The European Commission's own February 2016 factsheet on hair dye safety states the outcome in numbers: more than 100 hair dye substances have been assessed by the SCCS and found safe enough to be permitted under the Cosmetics Regulation, while more than 180 ingredients were banned, either because of a negative SCCS opinion or because industry had no interest in updating the safety dossier. That is why the hair dye section of Annex II is unusually long compared with other cosmetic ingredient classes — it is largely a record of substances the market walked away from, not a list of substances proven dangerous by a single mechanism.

Oxidative vs non-oxidative (direct) hair dyes

The Cosmetics Regulation and the SCCS treat two chemically different product families under the same "hair dye substance" heading. Oxidative (permanent) hair dyes work by mixing colourless or lightly coloured precursor molecules with hydrogen peroxide immediately before use; the precursors react and polymerise inside the hair shaft, which is why they resist washing out. Non-oxidative, or direct, dyes are pre-formed coloured molecules that coat the hair and are not mixed with peroxide; they wash out faster, which is also why the Commission's public information notes that permanent (oxidative) dyes are the ones of greater safety interest, since they account for the majority of colouring products sold in Europe.

cosingchecker.com keeps these as two separate product types: "Hair dye substance in oxidative hair dye products", which currently carries 86 Annex III entries, and "Hair dye substance in non-oxidative hair dye products", with 81. A single substance can carry both product types in the same Annex III row if it is permitted both ways, each with its own maximum concentration.

How an Annex III hair dye entry actually reads

An Annex III hair dye row is denser than most other restricted-substance entries because the columns are split by lettered sub-item — (a), (b), (c) — for each permitted product type. On cosingchecker.com/annex/III/ each entry shows: the product type(s) the substance is cleared for; the maximum concentration, which for oxidative use is expressed as the concentration applied to hair after mixing under oxidative conditions (not the concentration in the bottle before mixing); the mandatory warning text that must be printed on the label; and any other restrictions, such as professional-use-only or a separate, lower concentration limit for eyelash colouring.

The warning wording is fixed by the regulation itself, not left to the brand. For 2-methylresorcinol (Annex III entry 243), the label text required for oxidative hair dye use reads, verbatim, in the site's data:

A separate warning text applies where the same substance is also cleared for colouring eyelashes, and it adds eyelash-specific lines, including that the product is for professional use only and that eyes should be rinsed immediately on contact. Not every hair dye substance is cleared for eyelash use at all: Basic Orange 31, for example, has an Annex III entry covering only oxidative and non-oxidative hair dye product types, with no eyelash-colouring product type listed, so its record does not extend that clearance.

Worked examples: 2-methylresorcinol, 4-amino-2-hydroxytoluene, 2-nitro-p-phenylenediamine, 1,2,4-trihydroxybenzene, Basic Orange 31

2-Methylresorcinol (CAS 608-25-3, EC 210-155-8) is Annex III entry 243. Its record covers three product types: oxidative hair dye, non-oxidative hair dye, and eyelash colouring. The maximum concentration applied to hair after mixing under oxidative conditions must not exceed 1.8%, the non-oxidative concentration limit is also 1.8%, and the eyelash limit after mixing is 1.25%, restricted to professional use.

4-Amino-2-hydroxytoluene (CAS 2835-95-2, EC 220-618-6) is Annex III entry 241, covering oxidative hair dye and eyelash colouring only — it has no non-oxidative product type in the current record. After mixing under oxidative conditions the maximum concentration applied to hair or eyelashes must not exceed 1.5%, and the eyelash use is restricted to professional use only.

2-Nitro-p-phenylenediamine (CAS 5307-14-2, EC 226-164-5) is the clearest illustration of what the 2003 strategy produced: it is not in Annex III at all. cosingchecker.com's ingredient record lists it as Annex II, entry 1319 — "2-Nitro-p-phenylenediamine and its salts, when used as a substance in hair dye products" — meaning the substance, along with its dihydrochloride and sulfate salts, is prohibited in cosmetic products rather than permitted under conditions. Anyone searching "2 nitro p phenylenediamine" expecting a concentration limit will instead find a prohibition entry with no product type, warning text or concentration column, because none of those apply to a banned substance.

1,2,4-Trihydroxybenzene (CAS 533-73-3, EC 208-575-1) followed the same route more recently. The SCCS assessed the substance in opinion SCCS/1598/18, and Commission Regulation (EU) 2020/1683 of 12 November 2020, amending Annexes II and III to Regulation (EC) No 1223/2009, moved it into Annex II as entry 1642, covering its use "as a substance in hair and eyelash dye products." That regulation set 3 September 2021 as the date after which such products could no longer be placed on the EU market, with a longer sell-through window for stock already on shelves. cosingchecker.com's ingredient record for 1,2,4-trihydroxybenzene accordingly shows no Annex III restriction — only the Annex II prohibition.

Basic Orange 31 (CAS 97404-02-9, EC 306-764-4) is Annex III entry 276, permitted for oxidative and non-oxidative hair dye use. The non-oxidative maximum concentration is 1.0%. Its oxidative-use warning text carries the same core allergy and under-16 wording as 2-methylresorcinol's, which is typical of hair dye entries generally — the regulation reuses a small set of standard warning paragraphs across many substances rather than drafting bespoke text for each.

How another market treats the same substance

2-Nitro-p-phenylenediamine is also a useful case for comparing jurisdictions, because cosingchecker.com's jurisdiction data for it goes beyond the EU. Brazil's ANVISA lists the same substance and its salts, under RDC 529/2021 (consolidated through RDC 1.030/2026), as prohibited for use in hair-colourant compositions above a concentration of 1%, which is a restricted-use limit rather than an outright ban at every concentration — a materially different mechanic from the EU's Annex II prohibition. Great Britain's post-Brexit Cosmetics Regulation, by contrast, mirrors the EU position and lists the same substance at the same Annex II entry number, 1319, because GB inherited the EU annex text at the point of Brexit and has not diverged on this entry. Readers should treat any non-EU status shown on the site as that regulator's own published position, not as an EU determination, and verify current wording against the regulator's own source before relying on it.

What Annex III does not cover

Hair dye substances sit in Annex III, the general restricted-substances list, not in Annex IV, which is reserved for colorants identified by Colour Index (CI) number for use in the coloured part of a cosmetic formulation generally (eye makeup, lipstick, soap colouring and similar). Some hair dye substances, including several worked examples above, also carry a CI number in their chemical description, but that does not place them in Annex IV — the product-type restriction is what matters, and "hair dye substance" entries stay in Annex III. For how CI numbers and Annex IV work as their own system, see the companion article on cosingchecker.com about CI numbers and Annex IV colorants.

Reading the record correctly

An Annex III or Annex II entry is identity evidence for a substance under EU cosmetics law — it tells you what the regulation currently says about that CAS/EC pair — not a safety verdict and not permission to use a substance in a specific product without checking the full current wording at EUR-Lex or the current CosIng database. cosingchecker.com does not certify formulations or issue pass/fail judgments; if a substance has no entry in the site's Annex III or Annex II data, that reflects the state of the site's data, not proof that EU law is silent on it. Always confirm a live formulation decision against the current consolidated Regulation (EC) No 1223/2009 text and its annexes, or a qualified regulatory advisor.

Sources

• European Commission — "The EU is the safest market in the world for hair dyes" (factsheet, February 2016) — https://ec.europa.eu/health/scientific_committees/docs/citizens_hairdyes_en.pdf
• Commission Regulation (EU) 2020/1683 of 12 November 2020 amending Annexes II and III to Regulation (EC) No 1223/2009 — https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32020R1683
• Regulation (EC) No 1223/2009 on cosmetic products (Cosmetics Regulation) — https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A02009R1223
• cosingchecker.com — 2-Methylresorcinol, Annex III entry 243 — https://cosingchecker.com/annex/iii/iii-243-2-methylresorcinol/
• cosingchecker.com — 4-Amino-2-hydroxytoluene, Annex III entry 241 — https://cosingchecker.com/annex/iii/iii-241-4-amino-2-hydroxytoluene/
• cosingchecker.com — 2-Nitro-p-phenylenediamine and its salts, Annex II entry 1319 — https://cosingchecker.com/annex/ii/ii-1319-2-nitro-p-phenylenediamine-and-its-salts-when-used-as-a-substance-in-hair-dye-products/
• cosingchecker.com — 1,2,4-Trihydroxybenzene, Annex II entry 1642 — https://cosingchecker.com/annex/ii/ii-1642-124-trihydroxybenzene-when-used-as-a-substance-in-hair-and-eyelash-dye-products/
• cosingchecker.com — Basic Orange 31, Annex III entry 276 — https://cosingchecker.com/annex/iii/iii-276-basic-orange-31/
• cosingchecker.com — jurisdiction data for 2-nitro-p-phenylenediamine (Brazil ANVISA, Great Britain) — https://cosingchecker.com/ingredients/31506-2-nitro-p-phenylenediamine/
• cosingchecker.com — Annex III overview — https://cosingchecker.com/annex/III/
• cosingchecker.com — Annex II overview — https://cosingchecker.com/annex/II/
• cosingchecker.com — product type: Hair dye substance in oxidative hair dye products — https://cosingchecker.com/product-types/hair-dye-substance-in-oxidative-hair-dye-products/
• cosingchecker.com — product type: Hair dye substance in non-oxidative hair dye products — https://cosingchecker.com/product-types/hair-dye-substance-in-non-oxidative-hair-dye-products/