Octocrylene: Useful Stabilizer or Overused Filler?
The most debated workhorse filter, examined.
Tinosorb S and Tinosorb M have been used in Europe, Asia, and Australia for over two decades.
That Tinosorb S and Tinosorb M have a two-decade track record abroad shows the stability problem octocrylene solves was largely engineered out of newer filters.
Frequently asked questions
What does broad-spectrum protection actually mean?
'Broad-spectrum' means a sunscreen protects against both UVA and UVB. In the US a product must pass an FDA critical-wavelength test to make the claim. Because SPF only measures UVB protection, broad-spectrum labeling is how you know you're also covered against deeper, aging UVA rays.
Why are some UV filters more photostable?
A photostable filter keeps absorbing UV without breaking down in sunlight. Older filters like avobenzone can lose protection within an hour unless paired with stabilizers such as octocrylene. Next-generation filters are engineered to stay chemically stable, so protection lasts longer — though reapplication is still advised.
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.
r/SkincareScience: 'What's the difference between Mexoryl SX, XL, and 400?'
Sources & citations
- DermApproved, 'Tinosorb (Photostable UV Filters)' ingredient reference
- en.wikipedia.org ↗