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UV Filter

3-Imidazol-4-ylacrylic acid (Urocanic acid) and its ethyl ester

CAS 27538-35-8 / 104-98-3 Updated
22

Safety score · 0–100

Caution

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

About

Urocanic acid (and its ethyl ester) — a UV-absorbing molecule historically used in sunscreens, now restricted/prohibited in EU due to photoallergenic and immunosuppressive effects upon UV conversion to cis-isomer.

Skin benefits

  • UV-absorbing capacity historically used in sunscreens

Known concerns

  • Documented photoallergen
  • Suspected immunosuppressive on UV exposure
  • EU Annex II prohibition for direct cosmetic use
  • Photoreactivity converts trans- to cis- form linked to immune effects
  • No longer approved as UV filter in EU/most regions

References

EU

EU CosIng database

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

Related uv filters

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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.