What it is
Octocrylene is an organic (carbon-based) compound whose conjugated cyanoacrylate structure absorbs ultraviolet light in roughly the 280-320 nm region, covering UVB and the shorter-wavelength end of UVA. Because it is itself relatively resistant to breaking down in sunlight, formulators often pair it with photo-unstable filters, most notably avobenzone, to slow their degradation. It is oil-soluble and contributes an emollient, oily character to the finished product. On its own it is not a strong filter, so it is generally used as a supporting and stabilizing component rather than the primary protectant.
Spectrum coverage
UVA2 · UVB
Regional approval · max %
Safety & warnings
Octocrylene is generally well tolerated on the skin, but it is recognized as a possible cause of contact and photocontact allergy. Reviews describe a growing number of photoallergic reactions, with reported cross-reactivity in people sensitized to the topical anti-inflammatory drug ketoprofen, and a higher relative concern in children with sensitive skin; some sources suggest octocrylene-free products for very young children. People with a known ketoprofen photoallergy or a history of reactions to sunscreens may wish to be cautious.
Origin & sourcing
Octocrylene is a fully synthetic ingredient. It is an ester produced by a Knoevenagel condensation of 2-ethylhexyl cyanoacetate with benzophenone, which builds the diphenyl-substituted cyanoacrylate that does the light absorbing. It does not occur in nature.
Questions everyone asks
Why is octocrylene in so many sunscreens with avobenzone?
It is relatively photostable and is commonly added to help avobenzone, which breaks down in sunlight, last longer in the formula.
Does octocrylene protect against UVA or UVB?
Mainly UVB, plus the shorter-wavelength part of UVA, with peak absorption around 304 nm. It is usually combined with other filters for broader coverage.
Can octocrylene cause an allergic reaction?
It can occasionally cause contact or photocontact allergy, and people allergic to the drug ketoprofen may be more prone to react to it.