What it is
Polysilicone-15 is a polymeric, silicone-backbone UV filter built from a polysiloxane carrying benzylidene-malonate groups that do the ultraviolet absorbing. It protects in the UVB range, roughly 290-320 nm, with peak absorbance near 312 nm, so it is used to boost UVB protection rather than to provide UVA coverage. Because it is a large silicone polymer, it gives a colorless, comparatively non-shiny, pleasant skin feel relative to many other organic filters, and it can help stabilize the unstable UVA filter avobenzone and works well alongside ensulizole to build higher SPF.
Spectrum coverage
UVB
Regional approval · max %
Safety & warnings
As a high-molecular-weight silicone polymer, polysilicone-15 is large enough that it is not expected to penetrate skin readily, and it is regarded as a low-irritation, well-tolerated filter with a light cosmetic feel. Consumer ingredient references do not flag specific sensitization concerns for it. People with very reactive skin should still patch test any new sunscreen.
Origin & sourcing
Polysilicone-15 is a synthetic ingredient. It is a silicone polymer (a polysiloxane) onto which UV-absorbing benzylidene-malonate (benzalmalonate) groups have been attached, giving a single molecule that combines a silicone carrier with a built-in organic UV chromophore.
Questions everyone asks
What kind of UV protection does Polysilicone-15 give?
It absorbs UVB light, with peak absorbance around 312 nm, so it is used mainly to strengthen UVB protection.
Why does Polysilicone-15 feel lighter than other filters?
It is a silicone polymer, which gives a colorless and comparatively non-shiny, pleasant feel compared with many other organic UV filters.
Is Polysilicone-15 the same as Parsol SLX?
Yes, Parsol SLX is a common trade name for the UV filter polysilicone-15.