An indole-based dye ingredient used in oxidative hair colours, regulated in Annex III.
What it is
6-Hydroxyindole is 1H-indol-6-ol, an indole compound used as a dye component in oxidative hair colours. CosIng lists it as a hair-dyeing ingredient. In the EU it is covered by an entry in Annex III (substances subject to restrictions) for oxidative hair dye products, with a mandatory label warning.
Where it is used
Found in permanent (oxidative) hair colours.
Limits of interpretation
The INCI list shows which ingredients are present, not how much of each. Above 1%, ingredients are listed in descending order of weight; below 1% the order is free.
See the EU regulation section for the applicable limits, conditions and label warnings. Its position on the list does not show the final shade, which depends on the combination of dyes in the product.
Functions
- Hair dyeing
- Imparting color to hair. Hair dyeing preparations may be temporary, semi-permanent, permanent, depending on the length of time the colorant remains on the hair.
EU regulation
- Product type
- Hair dye substance in oxidative hair dye products
- Conditions and warnings
- To be printied on the label: Hair colorants can cause severe allergic reactions.
- As of
- 3 November 2026 · (EU) 2013/658