Ensulizole

Water-soluble UVB filter uniquely positioned for lightweight daily SPF formulations due to its polar sulfonic acid moiety. Non-greasy, clear-finish aesthetic makes it the preferred UV filter in facial moisturizers with SPF and cosmetic-adjacent products. FDA limbo due to systemic absorption detection in PK studies, not specific toxicity findings. EU-permitted at ≤4%. No significant endocrine or reef-toxicity profile relative to high-concern filters. Always requires co-formulation with a UVA filter for broad-spectrum compliance — UVB-only coverage is the primary limitation.

Historically marketed in the US; FDA states existing data is not sufficient to determine GRASE. Regulatory limbo alongside seven other chemical filters. Final determination pending additional safety data.