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Antimicrobial

COLLOIDAL SULFUR

CAS 7704-34-9
68

Safety score · 0–100

Fine

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

About

Colloidal sulfur — a classic acne and dandruff ingredient with real pharmacopoeial pedigree. Works, but it smells and can dry the skin.

Colloidal sulfur is finely divided elemental sulfur (CAS 7704-34-9) dispersed in water or another vehicle. It has long been used in dermatology as a keratolytic, antimicrobial, and antifungal agent in acne, rosacea, seborrhoeic dermatitis, and scabies treatments, and is listed in the USP and European Pharmacopoeia. In cosmetics it is permitted across the EU, US, and major markets at typical use levels of 1-10% in rinse-off and 1-3% in leave-on. Side effects are well characterised: distinctive odour, mild dryness or stinging, occasional peeling. Patch-test sensitisation is uncommon. Evidence is high thanks to a long medical history.

Function

ANTIMICROBIAL

Skin benefits

  • Anti-acne keratolytic
  • Antimicrobial for seborrhoeic conditions
  • Long pharmacopoeial record

Known concerns

  • Sulfurous odour
  • Drying/irritation at higher %
  • Staining

References

EU

EU CosIng database

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

Related antimicrobials

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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.