Ecamsule (Mexoryl SX): L'Oréal's UVA Innovation
The patented filter that gave the US a rare UVA upgrade.
Ecamsule (Mexoryl SX) received FDA clearance in 2006 through a New Drug Application for specific L'Oréal/La Roche-Posay products, rather than through the OTC sunscreen monograph.
Formulators note that ecamsule absorbs strongly in the shorter UVA range, so it is typically combined with avobenzone and octocrylene to extend and stabilize protection across the full UVA band.
Questions we get a lot
What is the difference between Mexoryl SX, XL and 400?
All three are L'Oréal/BASF UVA filters. Mexoryl SX (ecamsule) covers shorter UVA; Mexoryl XL (drometrizole trisiloxane) is broad-spectrum and oil-soluble; and Mexoryl 400 (MCE) targets ultra-long UVA1, peaking around 385 nm — the deep wavelengths most older filters miss.
Why was ecamsule a big deal for US sunscreens?
For decades the US OTC monograph offered limited UVA coverage. Ecamsule (Mexoryl SX) was cleared by the FDA in 2006 under a New Drug Application for specific products, giving American consumers a rare, dedicated UVA filter at a time when few were available domestically.
Is ecamsule used on its own?
Rarely. Because ecamsule concentrates its protection in the shorter UVA range, formulators pair it with other filters — commonly avobenzone for longer UVA and octocrylene for photostability — so the finished sunscreen delivers even, broad-spectrum UVA and UVB coverage.
r/SkincareScience: 'How is Mexoryl SX different from Mexoryl XL and Mexoryl 400?'