Mexoryl SX
Also known as: Ecamsule, Terephthalylidene Dicamphor Sulfonic Acid
L'Oréal's proprietary UVA filter — the one piece of modern filter tech US gets to have (limited).
What It Does
Deep Dive
Mexoryl SX was developed by L'Oréal and patented, which is both why it's excellent (serious R&D behind it) and why it's limited in distribution (mostly L'Oréal family brands: La Roche-Posay Anthelios, Vichy Capital Soleil, etc.). Got limited FDA approval in the US for specific Anthelios formulations in 2006. Performance is genuinely strong.
Best For
Pairs Well With
Effective Concentration
Up to 10% EU. L'Oréal patent, limited FDA approval in specific products.