What it is
Terephthalylidene Dicamphor Sulfonic Acid is an organic UV filter belonging to the benzylidene camphor family, developed and patented by L'Oreal. It is water-soluble and acidic, so it is typically neutralized in formulation, and it is noted for excellent photostability. On exposure to UV it absorbs energy and undergoes reversible photoisomerization and photoexcitation, converting the absorbed energy to heat with peak protection around 345 nanometers in the UVA range. It is generally combined with other filters to broaden overall protection.
Spectrum coverage
UVA1 · UVA2
Regional approval · max %
Safety & warnings
Ecamsule is generally regarded as well tolerated, and research indicates minimal skin absorption and systemic exposure, with studies reporting no evidence of photomutagenic activity. As an acidic filter it is neutralized in formulation, and it is usually paired with other filters for broad protection. As with any sunscreen active, anyone with a history of sunscreen sensitivity should patch test.
Origin & sourcing
It is a synthetic compound based on camphor-derived (benzylidene camphor) chemistry. Studies indicate it shows minimal skin penetration after topical application.
History
L'Oreal patented this synthetic compound in 1982. It gained EU approval in 1991, and European sunscreens containing it became available in 1993. In the United States the FDA approved it in 2006, specifically for particular sunscreen products registered under a New Drug Application rather than approving the ingredient on its own.
Questions everyone asks
Is ecamsule the same as Mexoryl SX?
Yes. Ecamsule is the common name for terephthalylidene dicamphor sulfonic acid, and Mexoryl SX is its trade name from L'Oreal.
What kind of UV protection does it provide?
It is an organic UVA filter with peak absorption around 345 nanometers and is valued for being photostable; it is usually combined with other filters for broad coverage.
Why is it less common in US sunscreens?
In the US it was approved in 2006 only for specific products registered under a New Drug Application, rather than as a generally available ingredient, which limited its use compared with Europe and Asia.