HC Yellow No. 4

What Is It?

HC Yellow No. 4, which refers to Hair Colorant Yellow No. 4, occurs as a fluffy yellow powder. HC Yellow No. 4 is used in the formulation of permanent and semi-permanent hair dyes and colors, as well as hair tints.

Why Is It Used?

HC Yellow No. 4 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

HC Yellow No. 4 is used in semi-permanent hair coloring systems that are usually applied in a shampoo base and contain thickeners, alkalizers, and foam stabilizers. HC Yellow No. 4 may also used in permanent hair coloring systems where color is produced inside the hair fiber. The color that is produced results from careful formulation of the product so that the ingredients interact in a highly controlled process.

Safety Information

The safety of HC Yellow No. 4 has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The CIR Expert Panel evaluated the scientific data and concluded that HC Yellow No. 4 was safe as a hair colorant in the present practices of use.

CIR Safety Review:

Dermal absorption studies using commercial products containing 1% HC Yellow No. 4 found little absorption. Body weight decreases were noted in short-term oral toxicity studies and in a subchronic oral toxicity study. HC Yellow No. 4 did not produce irritation, sensitization, or photosensitization. In some feeding studies, fetal toxicity was observed, but no such effect was found in other feeding studies. HC Yellow No. 4 was mutagenic in several assays, but no evidence of carcinogenesis was found in oral or dermal studies.

Two repeated insult patch tests, totaling over 200 human volunteers, found no sensitization reactions. While there was concern expressed over the reproduction and developmental toxicity found in feeding studies, such adverse responses would not be expected from the use of this ingredient in hair coloring products because so little HC Yellow No. 4 is absorbed. The presence of a low level of nitroaniline derivative impurity was not considered to present a human health risk because the products containing HC Yellow No. 4 are used in a brief and discontinuous manner, followed by rinsing.

More information about the safety of hair dyes

In Europe, HC Yellow No. 4 is permitted for use in non-oxidative hair dye products at a maximum concentration of 1.5%. See Annex III for additional information concerning the use of this ingredient in hair dye products 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. Temporary coloring preparations, often called color rinses, provide color which lasts until the first shampooing. Ingredients which impart temporary color may have a fairly high molecular weight and are unable to penetrate the hair shaft.

These materials are simply deposited onto the hair fiber and are removed by subsequent shampooing. Semi-permanent coloring preparations generally provide color through several shampooings. These materials are often low molecular weight pre-formed dyes which can penetrate the hair shaft to some extent. HC Yellow No. 4 is an aromatic compound also known as 2-([2-(2-Hydroxyethoxy)-4-Nitrophenyl] Amino) Ethanol. In cosmetics and personal care products, HC Yellow No. 4 functions as a hair colorant.


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

National Toxicology Program information on HC Yellow No. 4 http://ntp.niehs.nih.gov/index.cfm?objectid=BCA0BD80-123F-7908-7BD3CD8DE…

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/