p-Phenylenediamine HCl

What Is It?

p-Phenylenediamine, p-Phenylenediamine HCl and p-Phenylenediamine Sulfate are hair dye ingredients used in the formulation of permanent hair dyes, colors, and tints. p-Phenylenediamine appears as white to light purple crystals. The hydrochloride and sulfate salts of p-Phenylenediamine, p-Phenylenediamine HCl and p-Phenylenediamine Sulfate are white to gray powders.

Why Is It Used?

p-Phenylenediamine and its salts help to impart a color to hair. The exact color obtained depends on the other ingredients that are added to the hair coloring product.

Scientific Facts

p-Phenylenediamine, p-Phenylenediamine HCl and p-Phenylenediamine Sulfate 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.

Safety Information

The safety of p-Phenylenediamine, p-Phenylenediamine HCl and p-Phenylenediamine Sulfate has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The CIR Expert Panel evaluated the scientific data and concluded that p-Phenylenediamine, p-Phenylenediamine HCl and p-Phenylenediamine Sulfate were safe as hair dye ingredients.

CIR Safety Review:

The extensive safety test data on p-Phenylenediamine, p-Phenylenediamine HCl, p-Phenylenediamine Sulfate and permanent hair dyes containing these compounds showed that the degree of toxicity varies with concentration, test system and subject. The data supported a conclusion that these compounds were neither developmental toxicants nor carcinogens. Epidemiological data are insufficient to support a causal relationship between hair dye use and cancer.

The CIR Expert Panel noted that p-Phenylenediamine and its salts are sensitizers and some persons may be sensitized under intended conditions of use. The CIR Expert Panel expects that following label instructions on hair dye products will identify persons with irritation and sensitization reactions and allow them to avoid significant exposure. For those persons not sensitized to this hair dye ingredient, the CIR Expert Panel concluded that p-Phenylenediamine and its salts were safe for use in hair dye products.

More information about the safety of hair dyes.

p-Phenylenediamine, its N-substituted derivatives and their salts, and the N-substituted derivatives of o-Phenylenediamine are listed in the Cosmetics Directive of the European Union (see Annex III) and may be used as oxidizing coloring agents for hair dyeing at a maximum concentration of 6% (calculated as free base). Products containing p-Phenylenediamine or its salts must be labeled as indicated in Annex III.

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/