A trihydroxy phenol listed as a hair-dyeing ingredient and linked to an Annex II entry.
What it is
1,2,4-Trihydroxybenzene (benzene-1,2,4-triol, hydroxyhydroquinone) is a phenol with three hydroxyl groups on a benzene ring. CosIng lists it as a hair-dyeing ingredient. The EU data link this ingredient to an entry in Annex II (prohibited substances).
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 what the Annex II entry covers and how it applies.
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
- As of
- 3 November 2026 · (EU) 2020/1683
Scientific opinions (SCCS)
Opinions of the EU Scientific Committee on Consumer Safety that mention this ingredient. They assess specific uses and concentrations; read the opinion for its scope.