Me
Mexoryl XL
Drometrizole TrisiloxaneSPF filter
Modern UVB+UVA filter. Photostable, well-tolerated, EU/AU/JP-approved; not yet widely available in the US.
What it does
Mexoryl XL is a broad-spectrum filter developed by L'Oréal that covers both UVB and a meaningful portion of UVA. It's photostable (doesn't break down in sunlight) and stabilizes avobenzone when paired with it. Common in higher-end EU sunscreens. The US FDA has not yet approved it, which is why La Roche-Posay's US and EU formulations of the same-named sunscreen are different.
The evidence, graded
expert consensusSunscreen must be the final AM step. Applying products on top of sunscreen disrupts the protective film and can compromise the labeled SPF.Petersen 2014 · Photodermatology, Photoimmunology & Photomedicine ↗
expert consensusSPF protection degrades under UV exposure. Reapply sunscreen every 2 hours during continuous sun exposure to maintain rated protection — and immediately after swimming, sweating, or towel-drying.Petersen 2014 · Photodermatology, Photoimmunology & Photomedicine ↗
Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.
Also known as
drometrizole trisiloxane
Pairs worth knowing
This page is public and indexed on purpose (unlike profiles and drops, which are unlisted) — it’s the citation behind shared ingredient cards, and it should be findable.
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