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Hair Conditioning

ISOOCTYL THIOGLYCOLATE

CAS 25103-09-7
48

Safety score · 0–100

Moderate

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

About

Isooctyl thioglycolate — a fatty-ester thioglycolate used in perm waving. EU-restricted sensitizer; keep professional use with precautions.

Isooctyl thioglycolate (CAS 25103-09-7) is a thioglycolic-acid ester used as a reducing agent in hair-waving and depilatory formulations. Thioglycolic acid and its esters are regulated under EU Cosmetics Annex III entry 2 with concentration limits (8% in hair-waving/straightening, 11% in depilatories) plus mandatory professional-use warnings, glove-use recommendation, and pH restrictions. Thioglycolates are well-documented contact sensitizers — hairdresser hand dermatitis is a classic occupational condition traced to this chemistry. SCCS has reviewed the family multiple times and maintains the restrictions.

Function

HAIR WAVING OR STRAIGHTENING

Skin benefits

  • Reducing thiol for permanent waving
  • Less odor than ammonium thioglycolate
  • Works on hair disulfide bonds

Known concerns

  • Thioglycolates are strong skin sensitizers — EU restricted
  • EU Annex III entry for thioglycolic-acid esters: limits plus professional-use warnings
  • Scalp irritation and contact dermatitis documented
  • Accelerator-type sensitization risk

References

EU

EU CosIng database

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

Related hair conditionings

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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.