Hair colour is one of the most closely regulated cosmetic categories in Europe, because some dye substances can cause strong skin allergies. If you plan to sell a permanent colour, a toner or a colour shampoo, hair dye testing is not a single test but a package of evidence: a safety assessment of every dye, stability checks of the colour and the developer, microbiological quality and a clear plan for warnings and skin tests. This guide shows what that package usually contains.
Contents
- The short answer
- What counts as a hair dye?
- What do the EU rules require for hair dye substances?
- What does the safety assessment look at?
- Stability and compatibility of colour kits
- Microbiological quality of hair dyes
- Skin sensitisation and patch testing
- Colour performance, claims and marketing
- Labelling and instructions
- Hair dye testing checklist
- Common mistakes with hair dyes
- Frequently asked questions
- Key takeaways
The short answer
A hair dye is a cosmetic, so it needs a signed CPSR, a product information file and a CPNP notification, and each dye substance must be allowed and used within its limit. Expect to document the dye list and on-head concentrations, stability of both components of a two-part kit, the microbiological quality of the finished products, and the mandatory warnings. Human patch testing is treated carefully for oxidative dyes, so safety assessors rely mainly on substance data and on the instructions you give consumers.
What counts as a hair dye?
Several product types are covered and each has a different risk profile:
- Oxidative (permanent and some demi-permanent) dyes. Colour precursors react with an oxidising developer, usually hydrogen peroxide, to form the colour inside the hair. They are the most strongly regulated and the main source of allergic reactions.
- Direct (semi-permanent) dyes. Ready-made colour molecules that deposit on the hair without a developer.
- Temporary products. Colour sprays, mousses, waxes and colour shampoos that rinse out.
- Plant-based and “natural” colours. Henna and herbal powders are still cosmetics, and “natural” does not mean exempt from safety assessment.
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What do the EU rules require for hair dye substances?
Hair dye substances are mostly regulated through Annex III of Regulation (EC) No 1223/2009, which lists substances that may be used only within set conditions such as a maximum concentration on the hair and mandatory warnings. Some are listed as allowed only after the Scientific Committee on Consumer Safety (SCCS) reviewed them, and dyes that did not pass the review end up in Annex II as prohibited. The practical consequences for you:
- Check every colourant, coupler and precursor against the current annexes before you finalise the formula.
- Calculate the concentration that ends up on the head after mixing with the developer, not just the concentration in the tube.
- Remember that hydrogen peroxide is itself restricted in hair products, so the developer strength must stay within the legal limit.
- Ask suppliers for the purity and impurity profile of each dye, since impurities form part of the assessment.
What does the safety assessment look at?
The assessor works through the two CPSR parts. Part A collects formula, specifications, stability, microbiology and exposure data. Part B evaluates safety. For hair dyes, the assessor typically focuses on:
- exposure of a large area of scalp, repeated over months or years;
- skin sensitisation potential of each dye and of the reaction products;
- the behaviour of the mixture when the colour cream and developer are combined, including how long it stays on the head;
- accidental contact with the eyes and the risk to children;
- the quality of the instructions and warnings.
The SCCS Notes of Guidance are the reference document for these questions. See how this fits into our CPSR service.
Stability and compatibility of colour kits
Hair colour formulas are chemically active by design, so they change with time. A stability and compatibility test usually checks:
- the shade, viscosity and separation of the colour cream;
- the pH and the loss of alkalising agents such as ammonia or its replacements;
- the hydrogen peroxide content of the developer, which can decline over time;
- how the formula behaves in tubes, bottles and applicator bottles, including any gas build-up;
- how the mixed product behaves during the time the customer needs to apply it.
The results feed the shelf life and, for a multi-use bottle, the period after opening.
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Microbiological quality of hair dyes
Colour creams contain water, so they are not automatically low risk. Developers, which are acidic and contain an oxidiser, often support an argument for low microbiological risk under ISO 29621, but that argument must be documented by your assessor and not assumed. For the colour cream and for products such as colour shampoos and masks, run a microbiological specifications test on the finished product and, where the formula needs a preservation system, a challenge test following ISO 11930. Make sure the test sample is the final formula in its final packaging.
Skin sensitisation and patch testing
Sensitisation is the central safety question for oxidative dyes. Because deliberately exposing volunteers to known sensitisers is ethically sensitive, the safety case relies on substance-level data and on the label: the mandatory warnings and the instruction to carry out a skin allergy test before each use. A volunteer patch test remains useful for non-oxidative products such as colour conditioners, colour-depositing masks and temporary colours, and for scalp-care products in a colour range. Ask your assessor which skin data they need before you plan any study.
Colour performance, claims and marketing
Performance tests are not required by law for safety, but claims need evidence. Statements such as “covers grey hair”, “lasts up to 8 weeks”, “ammonia-free” or “vegan” must follow the common criteria of Regulation (EU) No 655/2013 and be supported by tests on hair tresses or by a user study. Avoid implying that a product is safe for sensitive skin or that it cannot cause allergies. Those claims are very hard to defend for a hair dye.
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Labelling and instructions
The label is part of the safety measures. Annex III attaches mandatory warnings to hair dye substances: the allergy warning, the restriction for persons under a set age, the warning about eyelashes and eyebrows, and the instruction to wear suitable gloves. Keep the wording exactly as the annex requires and translate it for every market where you sell. Add clear mixing ratios, application time and rinsing instructions, together with the INCI list, batch number and responsible person details.
Hair dye testing checklist
- List every dye, precursor and coupler and compare with Annexes II and III.
- Calculate on-head concentrations and check the developer strength.
- Collect supplier data including purity and impurities.
- Test stability and packaging compatibility of every component.
- Run microbiological testing and a challenge test where required.
- Agree the skin safety strategy with your assessor.
- Prepare warnings, instructions and claims evidence.
- Request the CPSR and notify in the CPNP.
Common mistakes with hair dyes
- Checking the tube concentration but not the on-head concentration after mixing.
- Testing the colour cream without testing it together with the developer.
- Calling a product “natural” and skipping the safety assessment.
- Using old warning wording that no longer matches the annex.
- Selling a dye in sample or travel sizes whose packaging was never tested.
Frequently asked questions
Do hair dyes need a CPSR?
Yes. All hair dyes are cosmetics and need a signed CPSR before they are placed on the EU market, including colour shampoos and temporary colours.
Is a patch test required for hair dye?
The law does not require a volunteer patch test as such. The safety case is built from substance data, warnings and instructions, and a patch test is mainly used for non-oxidative colour products.
Can I make my own hair dye formula from approved dyes?
You can, but the formula, the on-head concentration and the final product still need a full safety assessment, stability and microbiology data.
Key takeaways
- Hair dyes are strictly regulated: check every dye against the annexes and the limits.
- Assess the mixed product, not only the ingredients in the tube.
- Stability and microbiology are required for both components of the kit.
- Warnings and instructions are part of the safety case, so keep them exact.