Homosalate & Octisalate: The Quiet Workhorses in Your SPF
They barely block UV on their own, yet homosalate and octisalate show up in almost every chemical sunscreen — here's the clever chemistry reason why.
Salicylates such as homosalate (peak absorption ~306 nm) and octisalate are weak UVB absorbers used at high concentrations primarily to boost SPF, add water resistance, and dissolve crystalline filters like avobenzone and oxybenzone.
Photoprotection references describe salicylates as relatively weak UV absorbers whose real value lies in formulation — improving water resistance and solubilizing other actives so the finished product performs better than the filters would alone.
Questions we get a lot
What do homosalate and octisalate do in sunscreen?
They are weak UVB absorbers used at high concentrations to boost SPF, add water resistance, and dissolve other crystalline filters such as avobenzone and oxybenzone. Homosalate absorbs UV with a peak around 306 nm. Much of their value is as solubilizers that make the whole formula work better.
Are salicylate UV filters strong sunscreens on their own?
Not particularly. Salicylates like homosalate and octisalate are relatively weak UVB absorbers. They are valued more for boosting SPF, improving water resistance, and helping dissolve stronger filters than for the protection they provide alone.
r/SkincareAddiction: 'Why is homosalate in literally every chemical sunscreen if it's such a weak UV filter?'