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Colorant

2,3-Dihydro-1H-indole-5,6-diol and its hydrobromide salt (see note 17).

CAS 29539-03-5 - 138937-28-7
30

Safety score · 0–100

Caution

Derived from EU CosIng regulatory status, PubChem hazard data and published research. How we score.

A melanin-style hair dye precursor that darkens through oxidation. EU Annex III restricts it because of sensitization risk; only permitted within capped concentrations.

Function

HAIR DYEING

Skin benefits

  • Eumelanin-precursor self-darkening hair dye

Known concerns

  • EU Annex III restricted hair dye precursor
  • Sensitizer in oxidative dye chemistry
  • Strict concentration cap
  • Aromatic amine pathway

References

EU

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, so always read the physical product label and consult a healthcare professional for personal concerns.