N,N-Bis(2-Hydroxyethyl)-p-Phenylenediamine Sulfate

What Is It?

N,N-Bis(2-Hydroxyethyl)-p-Phenylenediamine Sulfate is a hair dye ingredient used in the formulation of permanent hair dyes and colors.

Why Is It Used?

N,N-Bis(2-Hydroxyethyl)-p-Phenylenediamine Sulfate imparts 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

N,N-Bis(2-Hydroxyethyl)-p-Phenylenediamine Sulfate is 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 N,N-Bis(Hydroxyethyl)-p-Phenylenediamine Sulfate has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The CIR Expert Panel evaluated scientific data and based on the available information, concluded that N,N-Bis(Hydroxyethyl)-p-Phenylenediamine Sulfate is safe for use as a hair dye ingredient.

According to the U.S. Food, Drug and Cosmetic Act, hair dyes are not subject to approval by FDA but are required to bear a caution statement and appropriate “patch test” instructions for determining whether the product causes skin irritation in the user. Patch test instructions call for a 24 hour patch on the skin of the user with the color solution and hydrogen peroxide mixed in the same manner as in use. This test is to be performed prior to each and every application of the hair dye.

CIR Safety Review:

N,N-Bis(2-Hydroxyethyl)-p-Phenylenediamine Sulfate administered at dietary concentrations of 0.3% for 13 weeks resulted in decreased body weights, feed consumption, serum iron concentrations and reduced pituitary weights. No effects were observed at dietary concentrations of 0.1%. The results from subchronic dermal studies at 1.0% were unremarkable. In sensitization studies, 3% N,N-Bis(2-Hydroxyethyl)-p-Phenylenediamine Sulfate induced delayed hypersensitivity. A 2% solution produced a strong contact allergic, but not a photoallergenic, response. A repeat insult patch test in 104 humans produced definite sensitization in one subject and possible sensitization in another. No developmental effects were produced by dermal administration of 1% N,N-Bis(2-Hydroxyethyl)-p-Phenylenediamine Sulfate or by administration of 0.3% N,N-Bis(2-Hydroxyethyl)-p-Phenylenediamine Sulfate in the diet. N,N-Bis(2-Hydroxyethyl)-p-Phenylenediamine Sulfate was neither hepatocarcinogenic nor a promoter of liver cancer.

More information about the safety of hair dyes.

In the European Union N,N-Bis(2-Hydroxyethyl)-p-Phenylenediamine Sulfate is permitted for use in oxidative hair dyes. The maximum concentration applied to the hair must not exceed 2.5% (calcuated as the sulphat). See Annex III for more information about the use of this ingredient in hair dyes in Europe.

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. N,N-Bis(Hydroxyethyl)-p-Phenylenediamine Sulfate is a substituted aromatic amine that is a derivative of p-phenylenediamine. In cosmetics and personal care products, N,N-Bis(Hydroxyethyl)-p-Phenylenediamine Sulfate is used as a hair colorant.


The European Commission’s Scientific Committee on Consumer Products (SCCP) opinion on N,N-Bis(2-Hydroxyethyl)-p-Phenylenediamine Sulfate http://ec.europa.eu/health/ph_risk/committees/04_sccp/docs/sccp_o_065.pdf

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

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