Avobenzone vs Ensulizole: which is worse?

What is Avobenzone?

Avobenzone (INCI: Butyl Methoxydibenzoylmethane) is a chemical UV filter that is the only FDA-approved broad-spectrum UVA-absorbing active sunscreen ingredient in the US that covers the full UVA spectrum (320–400 nm). It is inherently photounstable and must be combined with photostabilizers.

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.

Documented risks

Avobenzone: Avobenzone is effective and considered safe at approved concentrations (up to 3% in US OTC sunscreens). A 2019 FDA study found that several sunscreen actives including avobenzone were systemically absorbed above the 0.5 ng/mL threshold after repeated use, triggering a call for additional safety data. This does not indicate harm, but the FDA requested more studies under its proposed sunscreen monograph. Current evidence supports its continued safe use. No clear endocrine disruption or carcinogenicity at human exposure levels is established.

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.