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2D structural formula of p-Phenylenediamine


What is it?

“P-Phenylenediamine (PPD) is an organic compound with the formula C6H4(NH2)2. This derivative of aniline is a white solid, but samples can darken due to air oxidation.” Wikipedia

What are the effects?

This substance belongs to the groups:

P-Phenylenediamine, also known as paraphenylenediamine, p-Phenylenediamine (PPD), 4-aminoaniline, and 1 4 diaminobenzene, is an aromatic diamine.

It is isomeric with o-Phenylenediamine (OPD). Which means that they share an identical chemical formula, C6H4(NH2)2, but have different structures.

Both PPD and OPD have very similar properties when looking at how they affect us and the environment.

The European Chemicals Agency (ECHA) on P-Phenylenediamine

ECHA has classified P-Phenylenediamine (paraphenylenediamine) as:

  • toxic if swallowed
  • toxic in contact with skin (refers to the pure chemical, it is not acutely toxic in a cosmetic formulation)
  • toxic if inhaled
  • very toxic to aquatic life with long lasting effects
  • causing serious eye irritation
  • may cause an allergic skin reaction
  • causing damage to organs.

Due to its many negative effects, it was previously banned in Sweden. However, when Sweden entered the EU it was authorized again.

European database on cosmetic substances (CosIng) on P-Phenylenediamine

In CosIng you will find that P-Phenylenediamine and its salts are restricted for use in cosmetics within the European Union.  The restriction includes that products containing this ingredient should not be used on people younger than 16 years old.

CosIng also states that P-Phenylenediamine is a potent allergen. It is known to cause a difficult reaction when it comes in contact with skin. In fact, it is one of the most common cosmetic allergens.

Should you get a product, such as p-phenylenediamine hair dye, on your skin you should rinse it off immediately. Even if you are not currently allergic, the chemical does have a toxic effect that can cause skin-sensitizing issues.

This is why CosIng also states that p-Phenylenediamine hair dye should only be used by proffesionals.

The American Contact Dermatitis Society wanted to highlight this issue and awarded in 2006 P-Phenylenediamine the Allergen of the Year.


This chemical’s formula contains amines, as is visible in the names:

  • P-phenylenediamine
  • Paraphenylenediamine

That means, as with all product formulations that contain amines, that there is a risk that toxic nitrosamines are developed inside the product.

Moreover, P-Phenylenediamine is also a derivative of aniline which can be seen in one of its other names:

  • 4-aminoaniline

This adds to the questionability of this ingredient as aniline has numerous safety concerns. Aniline, however, will not be listed on the bottle as it is used in the manufacturing of other chemicals, including P-Phenylenediamine, and not as a stand-alone ingredient.

So even though it is not listed among the ingredients, products with P-Phenylenediamine may contain impurities from:

  • Nitrosamines –  Linked to endocrine disruption, cancer, organ system toxicity, and is prohibited to use in cosmetics in the EU and Canada.
  • Aniline – causes damage to organs by prolonged or repeated exposure, is very toxic to aquatic life, is suspected of causing genetic defects and cancer, and may cause an allergic skin reaction, according to the ECHA.

P-phenylenediamine (paraphenylenediamine) uses

p-Phenylenediamine in cosmetic products*,

In cosmetics, p-Phenylenediamine (PPD, Paraphenylenediamine) can mainly be found in:

  • Hair dyes
  • Eyelash colors
  • Bleaching products
  • Temporary tattoos

Pay extra attention to the ingredients if you find temporary ‘black henna’ tattoos, as it is might contain PPD. This is especially the case of “tourist tattoos” when it is sometimes used as an alternative to henna or mixed with henna.

Because as above mentioned, you should be careful using products containing PPD directly on the skin as it is a strong allergen.

The reason why you will find p phenylenediamine in hair dye (and other dyes) is that it turns black when oxidizing.

 PPD other uses

PPD is also used in fabrics, photographic film development processes, and in the synthetic fiber Kevlar. Kevlar is used in products such as bike tires, bulletproof vests, and sails.

It is not uncommon to use PPD to color clothes and leather dark.

We use the European Commissions definition of Cosmetics:
“Cosmetics range from everyday hygiene products such as soap, shampoo, deodorant, and toothpaste to luxury beauty items including perfumes and makeup”.

Did you find this ingredient in a product?

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