Ingredient dictionary

Phenylbenzimidazole Sulfonic Acid

Also listed as: Ensulizole

A water-soluble UV filter used in sunscreens. It absorbs UVB rays and helps protect skin from sunburn. It is on the label of 37 products in our library. Checked against our library November 6, 2026.

The catch: as a chemical UV filter, it may be avoided by people with very sensitive skin or those wanting a mineral-only sunscreen.

Chemical UV filters. Organic sunscreen filters such as avobenzone, octocrylene and homosalate.

What Phenylbenzimidazole Sulfonic Acid does

Absorbs UVB rays before they reach skin
Dissolves easily in water-based formulas
Often paired with other UV filters

Phenylbenzimidazole sulfonic acid is a synthetic organic compound made in a lab. Its sulfonic acid group lets it dissolve in water once neutralized with a base. That is why formulators can use it in water-based lotions, gels and creams.

Formulators use it because it absorbs UVB rays, the shorter wavelengths that mainly cause sunburn. It usually leaves little white cast and feels light rather than greasy. It is often paired with other UV filters. You will mostly see it in sunscreens and some self tanners.

Good for

People who want a water-based sunscreen with a lighter feel and are comfortable with a chemical UV filter.

Frequently asked questions

Is Phenylbenzimidazole Sulfonic Acid safe for sensitive skin?

Many people use it without trouble, but very sensitive skin can react to chemical UV filters. Patch testing a new sunscreen on a small area first is a simple, sensible step.

Is Phenylbenzimidazole Sulfonic Acid a mineral sunscreen filter?

No. It is an organic, chemical filter. Mineral sunscreens use zinc oxide or titanium dioxide instead. If you want mineral-only, look for those as the only UV filters on the label.