1H-Indole-2,3-Dione
Safety score · 0–100
Moderate
Derived from EU CosIng regulatory status, PubChem hazard data and published research. How we score.
About
Also known as isatin, this compound is used as a hair dye intermediate in EU Annex III-allowed formulations at up to 1.6%, serving as an oxidation dye precursor.
1H-Indole-2,3-dione (isatin) is an indole derivative used as an intermediate in oxidative hair dye formulations. It is listed in EU Annex III with a maximum concentration of 1.6% in the finished cosmetic product. As a hair dye intermediate, it reacts with couplers and oxidising agents to produce final colourants on the hair shaft. The safety evaluation for hair dye intermediates is based on their behaviour under oxidation conditions.
Function
Skin benefits
- Hair dyeing (oxidation dye precursor)
Known concerns
- EU Annex III restriction to 1.6% for hair dye use
- Hair dye intermediate — requires controlled oxidation conditions
- Potential sensitisation
References
EU CosIng database
European Commission cosmetic ingredient registry — regulatory status, restrictions, authorised functions.
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This profile is for educational purposes and does not constitute medical advice. Regulatory status and scientific understanding evolve — always read the physical product label and consult a healthcare professional for personal concerns.