Drometrizole Trisiloxane Best UV filter Anti-Ageing Drometrizole Trisiloxane at a glance Known more commonly as Mexoryl XL Photostable UVA and UVB filter Developed and patented by L’Oreal Not yet approved for wide use in the U.S. Drometrizole Trisiloxane description Drometrizole trisiloxane, known also by its trade name Mexoryl XL, is a photostable UVA and UVB filter developed and patented by cosmetics company L’Oreal. Since its UVA protection peaks at 340 nanometers, it’s generally best to see this combined with other UV filters whose protection peaks further along the UVA range, which goes up to 400 nanometers. Research has found that allergic reactions to drometrizole trisiloxane are considered rare; this UV filter is used in sun protection products sold in the EU, Canada, Australia, and Japan. It is not currently in wide use in the United States because the U.S. Food and Drug Administration says there is not significant evidence yet showing it to be generally recognized as safe and effective for over-the-counter sunscreen use. Interestingly, the FDA has allowed L’Oreal to market a sunscreen in the U.S. that contains this filter. Related ingredients: Mexoryl SX