Skip to content

Oxidative hair dye precursor (regulated allergen)

p-Phenylenediamine and its salts

CAS 106-50-3 / 624-18-0 / 16245-77-5
20

Safety score · 0–100

Caution

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

p-Phenylenediamine is a regulated hair dye precursor and a well-known potent skin allergen. EU rules cap concentration in hair color and forbid direct skin application.

Skin benefits

  • Workhorse oxidative hair dye precursor for permanent color
  • Provides deep dark shades in hair colorants

Known concerns

  • Strong contact allergen with well-documented sensitization risk
  • EU restricts use with strict concentration limits (max ~2% in dye)
  • Banned for direct skin use (e.g. black henna)
  • Cross-reactivity with related amines and dyes
  • Acute toxicity if misused, multiple reported serious reactions

References

EU

EU CosIng database

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

Check your shelf

Find p-Phenylenediamine and its salts in your products.

Scan any cosmetic product with LuxSense to see if it contains p-Phenylenediamine and its salts and get a full ingredient breakdown with safety scores.

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.