What Is It?

2,4-Diaminophenol and 2,4-Diaminophenol HCl are crystalline substances. These ingredients are used in hair dyes and colors.

Why is it used in cosmetics and personal care products?

2,4-Diaminophenol and 2,4-Diaminophenol HCl impart color to hair. The exact color obtained will depend on the other ingredients that are used in the preparation and the starting color of the hair.

Scientific Facts:

2,4-Diaminophenol and 2,4-Diaminophenol HCl are used in permanent hair coloring systems where color is produced inside the hair fiber. This is accomplished through careful formulation of the product so that the ingredients interact in a highly controlled process. 2,4-Diaminophenol and 2,4-Diaminophenol HCl are aromatic amines. 2,4-Diaminophenol may also be used to dye fur, and as an accelerator in photographic developers.

Safety Information:

The safety of 2,4-Diaminophenol and 2,4-Diaminophenol HCl has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The CIR Expert Panel evaluated the scientific data and concluded that 2,4-Diaminophenol and 2,4-Diaminophenol HCl were safe for use in hair dyes at concentrations up to 0.2% (as the free base).

More safety Information:

CIR Safety Review: 2,4-Diaminophenol HCl was a skin and ocular irritant but did not induce sensitization. Dermal application of 2,4-Diaminophenol was not carcinogenic and 2,4-Diaminophenol HCl produced no evidence of carcinogenic activity in National Toxicology Program bioassays. On the basis of available data, and the use of the product as a colorant in oxidative hair dyes, the CIR Expert Panel concluded that 2,4-Diaminophenol and 2,4-Diaminophenol HCl were safe for use in hair dyes at concentrations up to 0.2% (as the free base).

More information about the safety of hair dyes.

In the European Union, 2,4-Diaminophenol and 2,4-Diaminophenol HCl are not permited for use in hair dye products (see Annex II).

Link to the EU Cosmetic Regulation: http://europa.eu/legislation_summaries/consumers/product_labelling_and_packaging/co0013_en.htm

More Scientific Information:

Hair dyeing formulations belong to three categories – temporary, semi-permanent and permanent coloring of hair. The permanent hair dyeing formulations are often referred to as oxidative hair dyes which are generally marketed as two-component products. One component contains the compounds (precursors) that become the colorants and the other component is a stabilized solution of hydrogen peroxide. The two components are mixed immediately prior to use. The precursors and peroxide diffuse into the hair shaft, where color formation takes place after the ingredients combine to produce the coloring mixture. The precursors are oxidized by the hydrogen peroxide to form the colorant molecules. These molecules are too large to escape from the hair structure. The hydrogen peroxide in the oxidative hair dye product also serves as bleaching agent for the natural pigment of the hair. The color that is formed depends on the precursors and direct dyes present in the dyeing solution, pH of the dyeing solution and the time of contact of the dyeing solution with the hair.


The FDA’s factsheet on Hair Dye Products http://www.fda.gov/Cosmetics/ProductandIngredientSafety/ProductInformati…

Search the FDA Code of Federal Regulations http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm

EU Cosmetic Ingredients Inventory http://ec.europa.eu/consumers/cosmetics/cosing/