Octocrylene
Also known as: 2-Ethylhexyl 2-cyano-3,3-diphenylacrylate
The photostabilizer doing 90% of the invisible work in your US sunscreen — and the one with a slightly awkward aging problem.
What It Does
Deep Dive
Octocrylene is a chemical UV filter that absorbs UVB and a sliver of short UVA-II. On its own it's a mediocre filter; its real job is stabilizing avobenzone, which otherwise degrades 36% within an hour of sun exposure. That's why you'll see octocrylene in nearly every US chemical sunscreen — not for its protection, but for its babysitting of the actual UVA filter. The controversy: octocrylene can degrade over time into benzophenone, a suspected endocrine disruptor. A 2021 study found measurable benzophenone in expired sunscreens. Takeaway: octocrylene is safe in fresh product, but don't stockpile sunscreen for three summers. Use it up; buy fresh yearly. EU/Asian sunscreens increasingly skip octocrylene in favor of Tinosorb S/M, which don't need a babysitter.