Ensulizole vs Zinc Oxide: which is worse?

What is Ensulizole?

Ensulizole (INCI: Phenylbenzimidazole Sulfonic Acid) is a water-soluble UVB-absorbing chemical sunscreen active. Because it is water-based, it provides a lighter, less oily feel compared to oil-soluble UV filters.

What is Zinc Oxide?

Zinc oxide is an inorganic mineral UV filter and skin protectant that provides broad-spectrum UVA and UVB protection by reflecting and scattering UV radiation. It is also an FDA-approved OTC active for diaper rash, minor skin irritation, and sunburn treatment.

Documented risks

Ensulizole: Ensulizole is approved by the FDA at up to 4% and in the EU at up to 8%. It is water-soluble and less likely to cause sensitivity reactions than oil-soluble filters. Minimal systemic absorption is documented. No established carcinogenicity or endocrine disruption. As with other UV filters, phototoxicity and photocontact dermatitis are very rare possibilities.

Zinc Oxide: Bulk zinc oxide used in traditional formulations has an excellent safety record. The primary concern is nanoparticle zinc oxide (nano-ZnO) used in transparent sunscreen formulations: the EU has reviewed nano-ZnO and found it safe for use in non-spray sunscreens (SCCS opinion 2022), but restricted it in spray products due to inhalation risk. Nano-ZnO does not penetrate intact skin. Zinc oxide is non-carcinogenic, non-hormone-disrupting, and reef-safer than chemical filters.