60% of Hair Dyes Claiming to Have “Natural” Ingredients Contained Allergens or Heavy Metals Calling for Prudent Use of Permanent Hair Dyes and Hennas

15 March 2021
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6成标榜成分天然染髮剂含致敏物质或重金属   永久性染髮剂及海娜染髮粉须慎用

It saves time and money to dye hair at home. Some consumers may use hair dye products with natural claims with the assumption that they may reduce the risk of allergies or cause less damage to the hair. However, the Consumer Council tested 26 hair dyes labelled with "natural", "herbal", "plant-based", or "organic" claims, and found that 60% of these models, all of which were oxidative dye type permanent hair dyes and hennas, contained allergens or heavy metals, posing higher health risks to users. Consumers should exercise prudence in choosing and using these products, rather than assuming that these "natural" products are safer.

All oxidative dye type permanent hair dyes tested were detected with allergens.  1 of them even contained prohibited mutagens, and some of them were also detected with ammonia. As chemicals in permanent hair dyes open up the cuticles of the hair to allow the dyes to enter the cortex, these chemicals may induce allergic reactions and damage the hair surface, resulting in dry or frizzy hair. Lead was detected in all henna type hair dye models, and the total aerobic bacterial count in all of them exceeded the allowable limit of the Technical Safety Standard of Mainland China, 3 of the models had even higher allergen content than permanent hair dyes. Since the application duration of hennas may often take as long as 3 to 5 hours, and frequent re-dyeing is needed, the presence of chemicals and aerobic bacteria increases their health risks. As for colouring conditioners, although they performed the best in the chemical test, with neither allergens nor heavy metals detected, the colouration effect is only semi-permanent, as the molecules of the dyes will only stay on the hair surface and will fade out easily, possibly requiring frequent re-dyeing.

The test covered 26 semi-permanent or permanent hair dye models priced from $18 to $450, including 7 colouring conditioners, 13 oxidative dye type permanent hair dyes and 6 hennas, mainly in colours of black and dark brown. The test covered 8 allergens commonly used in hair dyes, ammonia, heavy metals, pH values, etc, and the total aerobic bacterial count in henna models. The labelling information of each model was also reviewed.


In the test, 16 models were detected with harmful allergens, with half (8) of them containing 3 to 4 types of allergens. The 3 allergens found among these 16 models, namely p-Phenylenediamine (PPD), m-Phenylenediamine (MPD) and Toluene-2,5-diamine (PTD) were on the Poisons List of Pharmacy and Poisons Regulations.

PPD is commonly used in oxidative dye type hair dyes to produce colourful dye compounds upon mixing with other chemical substances. According to the cosmetic regulations of the EU and Mainland China, the use of PPD is restricted to oxidative dye type hair dyes with a concentration not exceeding 2% when applied on hair. The test result revealed PPD was detected in 11 tested models, of which 8 were oxidative dye type permanent hair dyes with detectable content between 0.29% and 2%, in compliance with relevant regulations. The remaining 3 models with PPD between 0.44% and 8.3% were henna dyes. Since henna is not a type of oxidative hair dye and the 3 models detected with PPD were not labelled with hydrogen peroxide, they did not comply with the restriction requirement under the EU and China cosmetic regulations. Consumers should be aware that studies have indicated that some people, particularly women, might develop allergic reactions towards PPD, which may cause pruritus, pricking or burning sensations, or in more severe cases, even complications such as contact urticaria, angioedema, bronchospasms, etc.

1 oxidative permanent hair dye model was detected with 0.02% of MPD, a mutagenic ingredient prohibited by the EU and Mainland China in cosmetics (including hair dye products). In addition, 6 models were detected with between 0.37% and 1.4% of PTD, complying with relevant regulations of Mainland China.

Furthermore, p-Aminophenol (PAP), resorcinol and m-Aminophenol (MAP) are regarded as allergens and acute toxic substances. The test found 4 models with PAP between 0.06% and 4.5%, of which the henna model contained the highest level of PAP (4.5%), which did not comply with related requirements for restricted use as it was not an oxidative hair dye.

Although the detectable content of resorcinol in 7 models ranged from 0.29% to 1.5%, complying with related regulations, 4 of them did not indicate resorcinol on their packaging or list of ingredients. 1 of them was even labelled with “does not contain resorcinol” and this has been referred to the Customs and Excise Department for follow up. 9 models were detected with between 0.04% and 0.61% of MAP, which complied with relevant regulations of the EU and Mainland China.


Henna is widely used as a natural hair dye, but its bacterial content is always a concern. 6 henna models were tested and total aerobic bacterial counts were found to be between 4,400 and 250,000 CFU/g, all exceeding the allowable limit (1,000 CFU/g) in other cosmetic products category under the Safety and Technical Standards for Cosmetics of Mainland China. The model with the highest bacterial count exceeded the limit by 250 times. There were 3 models detected with 4,000 to 34,000 CFU/g of total combined moulds and yeast count, exceeding the allowable limit (100 CFU/g) by 340 times at most. Although normal usage of hair dye products with high bacterial content may not lead to adverse health effects, but in case there are cuts on the scalp, or the product accidentally splashes into the eyes, they may cause allergies or even inflammation.

For the heavy metals test, all 6 henna models were detected with lead from 0.4 to 3.1ppm, of which 1 model was also found with 0.043 ppm of mercury. All detectable contents were lower than the upper limit of Mainland Chinese standard.


Ammonia is often added to oxidative permanent hair dyes to make the dyes stay permanently in the hair. However, ammonia has a pungent odour and can easily cause allergy to the scalp and eyes. The test revealed that 1 colouring conditioner model and 4 oxidative dye type permanent hair dye models were detected with 0.1% to 0.45% of ammonia. Although the detectable content complied with the regulations of the EU and Mainland China, all 5 models did not list ammonia on their labels, while 2 of them even labelled the product as “does not contain ammonia”. The data were referred to the Customs and Excise Department for follow up.


The test also reviewed the ingredient labelling of each model. In the 16 models detected with allergens, only 9 of them clearly listed out all allergens, while 7 of them did not indicate details of all allergens and related warnings on their bottle or packaging to remind consumers of the possible risks, hence failing to comply with the requirement of the Pharmacy and Poisons Regulations. Relevant information was referred to the Drug Office of the Department of Health for follow up. In addition, 2 models did not indicate the application duration, rendering it difficult for consumers to grasp the accurate duration of dyeing. Insufficient dyeing time may not achieve the desirable effect and if the dyeing time is too long it may increase health risks. 4 models did not indicate any information on expiry date. The Council urges for improvement in their labelling.

Consumers should pay attention to the following when purchasing and using hair dyes:

- Be mindful of the ingredients listed on the product packaging. If allergy happened during previous hair dyeing, one should avoid choosing products with the same allergens;
- Before dyeing hair, perform a skin allergy test according to the product instruction, in order to minimise the possible health risks caused when dyeing hair;
- When using hair dye products, read the instructions, usage, precautions, recommended duration of dyeing, etc, stated in the product label in detail, and use the products properly and safely;
- Ammonia and hydrogen peroxide are often added to permanent hair dyes, which may cause allergies and damage to hair surface, resulting in dry or frizzy hair;
- If you have eczema, itchiness or even damaged scalp surface, you should avoid dyeing your hair;
- People suffering from Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency should not use henna to avoid severe symptoms of haemolysis which pose risks to their lives;
- If you feel itchy or even a burning sensation when using hair dyes, rinse them off immediately. If the symptoms on the skin persist, you should seek medical advice as soon as possible.

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