Ensulizole (INN;[1] also known as phenylbenzimidazole sulfonic acid) is a common sunscreen agent.

In 1999, the United States Food and Drug Administration regulated that the name ensulizole be used on sunscreen labels in the United States.

[2] For better UVA protection, it must be paired with avobenzone, titanium dioxide, or zinc oxide; outside of the United States it can also be paired with a UV absorber of the Tinosorb or Mexoryl types.

Because ensulizole is water-soluble, it has the characteristic of feeling lighter on skin.

As such, it is often used in sunscreen lotions or moisturizers whose aesthetic goal is a non-greasy finish.