Phenylbenzimidazole Sulfonic Acid

Phenylbenzimidazole Sulfonic Acid


  • CAS #: 27503-81-7 | EC #: 248-502-0
  • Chemical/IUPAC Name: 2-Phenyl-1H-Benzimidazole-5-Sulphonic Acid
  • Cosmetic Restrictions: VI/6

Quick Facts

  • Also known as Ensulizole
  • Water soluble sunscreen ingredient that works at offering full protection from UVB, but none for UVA
  • It is still undergoing extensive research which explains why it is not a common sunscreen ingredient
  • Compared to other sunscreen ingredients it is a lot lighter in texture and consistency
  • Is often added to skincare formulations to prevent them from becoming discoloured

Who can use it?

Ideally it is best to check that your skin will be ok with you applying this chemical sunscreen. This is due to the fact there are still a lot of research to be complete around this ingredient.

What is Phenylbenzimidazole Sulfonic Acid

More commonly known as Ensulizole, Phenylbenzimidazole sulfonic acid is a chemical sunscreen ingredient that provides complete protection from exposure to UVB rays, but not from UVA rays. As previously mentioned, there is still studies underway due to the fact there have been very few reports of allergic reactions to the skin. With 4% concentrate passing the safety claims you can actually expect to find this ingredient in formulations because of how light weight and less oily it is compared to other sunscreens. It also contains salts that are included into skincare products in clear packaging to prevent the formulas from becoming discoloured, apart from this you won’t find this to be a common sunscreen ingredient.

Side effects of Phenylbenzimidazole Sulfonic Acid

Some signs of sensitivity and irritation to the skin if applied before performing a patch test for 24 hours to avoid allergic reactions.


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