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HC BLUE NO. 4

CAS 158571-57-4
38

Safety score · 0–100

Caution

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

About

A synthetic hair dye intermediate classified as a coal tar dye under EU Annex III restriction II/1256, permitted only under strict concentration and labeling requirements.

HC Blue No. 4 is an oxidation hair dye precursor listed in EU cosmetic regulation Annex III, part 2, entry II/1256. This entry specifically regulates synthetic hair dye intermediates permitted for use in non-oxidative and oxidative hair dye formulations with maximum concentration limits. The SCCS has issued opinions on this substance, and specific purity criteria apply regarding intermediate and byproduct content. Proper use requires caution for skin sensitization, and instructions must specify preliminary patch testing.

Skin benefits

  • Provides blue/violet tones in semi-permanent hair coloration
  • Used in oxidative and non-oxidative hair dye systems

Known concerns

  • EU Annex III restricted (II/1256) — permitted only at specified concentrations
  • Known hair dye allergen — patch test recommended
  • May cause skin sensitization especially on dyed or damaged scalp
  • Subject to IFRA/ cosmetics fragrance and dye safety standards

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