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BASIC BLUE 9

CAS 61-73-4
30

Safety score · 0–100

Caution

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

A triphenylmethane dye (Methylene Blue) restricted in the EU to rinse-off hair dye formulations with strict concentration limits.

Basic Blue 9 (Methylene Blue) is listed in EU CosIng Annex II/1306, restricting it to rinse-off hair dye use only at a maximum concentration of 2% (as the dye). Its molecular size limits systemic absorption, but it can cause eye irritation and is a known photosensitizer. The compound has been associated with DNA intercalation concerns in in vitro studies, which is why its cosmetic use is heavily restricted in Europe.

Known concerns

  • EU Annex II rinse-off only restriction (II/1306)
  • Photosensitization potential
  • Eye irritation

References

EU

EU CosIng database

European Commission cosmetic ingredient registry: regulatory status, restrictions, authorised functions.

Same plant / compound family

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BASIC BLUE 124
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BASIC BLUE 26
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BASIC BLUE 3
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BASIC BLUE 41
industrial dye (non-cosmetic)
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BASIC BLUE 47
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 25
BASIC BLUE 6
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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.