A synthetic non-oxidative hair dye, regulated in Annex III.
What it is
Dihydroxyindoline HBr is 2,3-dihydro-1H-indole-5,6-diol hydrobromide, the hydrobromide salt of 5,6-dihydroxyindoline, a compound structurally related to precursors of the pigment melanin. 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 non-oxidative hair dye products, with mandatory label warnings.
Where it is used
Appears on the ingredient lists of a small number of products.
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 non-oxidative hair dye products
- Maximum concentration
- 2.0%
- Conditions and warnings
- - Can cause allergic reaction - You have ever experienced any reaction afther colouring your hair - You have experienced a reaction to a temporary 'black henna' tattoo in the past
- As of
- 3 November 2026 · (EC) 2013/344