This content was created by Jane Yoo. This content was uploaded by Jane Yoo. This is a YouTube video titled "Bemotrizinol vs. Avobenzone: Why Photostability Actually Matters" (created 2026-08-12T13:00:03Z). It features Dr. Jane Yoo (board-certified dermatologist and Mohs surgeon) delivering an explanatory monologue about sunscreen photostability: comparing avobenzone (a common UVA filter that is photounstable and can lose ~36% of UVA protection within an hour unless stabilized) with bemotrizinol/bimotrizole (described as retaining >98% UV absorption after heavy exposure and having dual absorption peaks at ~310 nm and ~340 nm). The video explains the clinical and practical implications for daily sunscreen performance and reapplication habits, and notes this is not a claim that avobenzone is unsafe.
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Hi everyone, I'm Dr. Jane Yoo, board-certified dermatologist and Mohs surgeon. Now that bimotrizole is approved in the US, I want to walk through exactly why the photostability difference between this filter and avobenzone actually matters and how your sunscreen performs across a real day. Avobenzone is a workhorse UVA filter in most American sunscreens. It's effective, But it has one real weakness. It's photounstable. That means it breaks down when left exposed to UV light. Left on its own, Avobenzone can lose up to 36% of its UVA protection within just 1 hour of sun exposure. That's why most US formulas pair it with stabilizers like octocrylene to slow that degradation down. Even stabilized though, the protection curve declines over the course of the day. Bimotrizole behaves completely differently. It retains over 98% of its UV absorbing capacity even after 50 minimal erythemal doses, which is a lab measure of substantial cumulative UV exposure. In practical terms, that means the sunscreen you apply at 8 AM is still doing close to the same job at noon, without needing a stabilizing partner ingredient to prop it up. Here's why this matters clinically. A lot of patients tell me, well, I put on sunscreen and I still got sunburned and I still have hyperpigmentation even though I use SPF every day. Reapplication habits are part of that story, but so is the filter degradation. If your morning sunscreen is quietly losing a third of its UVA protection by lunchtime, that's real measurable protection you're missing during peak sun hours, even if you never noticed it happening. Bimotrizole also has 2 separate absorption peaks, one at 310 nanometers in the UVB range and one at 340 nanometers in the UVA1 range, so it's doing genuine broad-spectrum work as a single molecule rather than relying on a blend of several filters stacked together to cover the same range. None of this means avobenzone is unsafe or that you need to throw out your current sunscreen. But as bimotrizinol formulations start reaching US shelves, this is the actual mechanism behind why they're likely to feel more reliable across a full day of wear, not just the first hour after application.
