DIHYDROXYACETONE

Name / description

Dihydroxyacetone, 1,3-Dihydroxyacetone

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Function(s) of this ingredient in cosmetic products

HAIR DYEING

Colours the hair

SKIN CONDITIONING - MISCELLANEOUS

Maintains the skin in good condition

TANNING

Darkens the skin (with or without exposure to UV light)

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Origin

synthetic

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Occurrence in cosmetics

Self-tanning products

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Background information on use in cosmetics

Dihydroxyacetone (DHA) is a popular active ingredient for self-tanning products. The brown colouring of the skin (without any exposure to harmful UV radiation) is obtained through the reaction of DHA with the keratin of the stratum corneum. Skin tanned with self-tanning agents offers, however, no additional UV protection. Cosmetic hair dyes are subdivided according to different operating principles. There are temporary dyes (tints), semi-permanent dyes (semi-permanent hair colours) and permanent dyes (oxidation dyes or bleaches). Temporary dyes are characterised by the use of direct dyes (eg cationic dyes such as Basic Red 56 or Acid Blue 62). There is no chemical reaction with other components; the dyes adhere to the hair surface and last for one to two hair washes. For temporary hair dyes, azo, triphenylmethane or anthraquinone dyes are used. The temporary dyes are sold as aqueous alcoholic solutions. In combination with hairspray, it is also possible to apply very small golden or silver gloss pigments or even fluorescent substances to the hair. Semi-permanent dyes (tints) also use direct dyes (eg nitro dyes such as HC Blue 2 or HC Yellow 10). The hair is coloured circularly, which ensures that it lasts for eight to 10 hair washes. Nitro dyes diffuse because of their low molecular size into the hair but are washable. Other dyes which are used include nitrophenyl diamines, azo and quinonimine dyes in combination with organic solubilizers such as glycol ether or polypropylene. In the event of permanent dyes (oxidative hair dyes), colourless precursors, also referred to as developers and couplers, are first used. The actual dyes are formed through a chemical reaction. The entire hair is dyed and the colour is not washable.

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Information on safe use

Hair colourants are at present amongst the most thoroughly examined cosmetic products on the EU market. Since 2003 the European Commission has pursued a global strategy for the safety assessment of hair colourants and hair dyes in Europe. More than 100 individual hair colourants were considered as safe by the Scientific Committee for Consumer Safety (SCCS) of the EU Commission after a comprehensive assessment and are allowed for use in Annex III of the EC Cosmetics Regulation. https://ec.europa.eu/health/scientific_committees/docs/citizens_hairdyes_en.pdf This substance is expressly approved and / or subject to a restriction as a result of an entry in Annex III of the EC Cosmetics Regulation after an assessment by the Scientific Committee on Consumer Safety of the EU Commission (SCCS). Restrictions can relate eg to purity criteria, a maximum concentration or the restriction to certain product categories. Subject to the conditions possibly imposed in Annex III, the use of this substance in cosmetic products is safe.

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Links to scientific assessments

Opinion of the SCCS (2021) on the safety as cosmetic ingredient

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Belongs to the following substance groups

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Regulating cosmetics

Cosmetics Ingredients are subject to regulation. Please note, different regulations may apply to cosmetic ingredients outside the EU.