For your skin
The quiet workhorse of chemical sunscreens: it adds UVB coverage but its real job is keeping avobenzone from falling apart in the sun, which is why the two are almost always paired. Well-established and effective. The one watch-point is that older, expired bottles can build up a benzophenone impurity, so do not hoard chemical sunscreens for years.
Want the science? Keep reading ↓Mechanism of action
Absorbs UVB and short UVA2 (280-320 nm) and, most importantly, photostabilises avobenzone: its structure dissipates absorbed energy and prevents avobenzone from degrading in sunlight, so it appears in most avobenzone-based Western sunscreens for that reason as much as its own filtering. FDA-approved OTC at up to 10%. A known caveat is that octocrylene can slowly degrade into benzophenone (a suspected carcinogen/allergen) as products age, so formulation freshness matters.
Why we tier this moderate
2 cited papers across 1 country. The mechanism is well-described and there's at least one controlled trial in the literature, but we tier this Moderate rather than Strong to stay honest about how many specific papers we cite directly.
Cited research
Matta MK et al., Effect of Sunscreen Application Under Maximal Use Conditions on Plasma Concentration of Sunscreen Active Ingredients: A Randomized Clinical Trial, JAMA 2020;323(3):256-267 — octocrylene systemic absorption measured; a widely used avobenzone photostabiliser
FDA Proposed Rule, Sunscreen Drug Products for Over-the-Counter Human Use, 84 FR 6204 (26 February 2019) — octocrylene among the organic filters with GRASE status pending additional data
Sources: PubMed · KCI · J-Stage · CNKI · Wanfang · SFD · MFDS · Cochrane · SCCS · CIR. Every entry points to a specific document. See methodology for what each outcome label means.