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Hair Conditioning

AMIDINOCYSTEINE

CAS 40454-21-5 Updated
55

Safety score · 0–100

Moderate

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

About

A guanidinated cysteine derivative used as a reducing agent for hair waving — like thioglycolate, it breaks hair's disulfide bonds. Functional but inherently aggressive on hair/scalp.

Function

HAIR WAVING OR STRAIGHTENING

Skin benefits

  • Hair waving / straightening
  • Cysteine-derived reducing agent

Known concerns

  • Aggressive by design — breaks disulfide bonds
  • Possible scalp irritation/sensitization
  • Strong sulfurous odour

References

EU

EU CosIng database

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

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BEHENYL HYDROXYETHYL IMIDAZOLINE
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BIS-(MORPHOLINOMETHYL C1-4 DIALKOXYSILOXY) DIMETHICONE
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BIS-HYDROXYETHYL TALLOWMONIUM CHLORIDE
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CETETHYLDIMONIUM BROMIDE
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CETRIMONIUM CHLORIDE
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CINCHONA PUBESCENS BARK EXTRACT
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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.