Why Avobenzone and Octocrylene Are Always Together
Flip over almost any US chemical sunscreen and you'll see avobenzone next to octocrylene — here's the formulation logic behind that duo.
Avobenzone is photolabile and degrades quickly in sun, but pairing it with octocrylene as a triplet-state quencher and solubilizer substantially improves its photostability, explaining why the two filters so frequently appear together on US labels.
Formulation chemists describe octocrylene as one of the workhorse stabilizers for avobenzone, noting that without a photostabilizing partner avobenzone can lose a large share of its UVA-filtering ability after sun exposure.
Questions we get a lot
Why does avobenzone break down in sunlight?
Avobenzone is photolabile, meaning its molecular structure is destabilized by UV energy and it degrades relatively quickly once exposed to sun. As it breaks down, it loses its ability to filter UVA rays. That is why formulators add stabilizing ingredients to keep it effective over a day of wear.
What does octocrylene do in sunscreen?
Octocrylene contributes some UV filtering of its own, but its key role in many formulas is stabilizing avobenzone. It acts as a triplet-state quencher and solubilizer that helps avobenzone resist breaking down in sunlight. This is why the two ingredients are so often paired on US sunscreen labels.
r/SkincareAddiction: 'Why does every American chemical sunscreen have avobenzone AND octocrylene? Is octocrylene actually doing anything?'