What it is
Octinoxate is one of the most widely used organic UVB filters, chemically the ester of 2-ethylhexyl alcohol and methoxycinnamic acid. It absorbs UVB radiation with peak protection around 310 nm and is a clear, oil-soluble, cosmetically light liquid that is easy to formulate. Its main drawback is photoinstability: on sun exposure it converts from its more absorbing form to a less absorbing isomer and loses part of its protective ability, so it is often paired with more stable filters for durable broad-spectrum coverage. It protects against UVB but not UVA on its own.
Spectrum coverage
UVB
Regional approval · max %
Safety & warnings
Octinoxate is a well-known UVB filter with a long record of use, but it is among the organic filters more often discussed for skin sensitivity, and some people experience contact or photo-contact reactions. Laboratory studies have raised questions about potential hormonal activity, though these were not human studies; as a precaution some sources suggest mineral filters for pregnant individuals and young children. Anyone with a history of reactions to chemical sunscreens may prefer to patch test.
Origin & sourcing
It is a fully synthetic compound produced as an ester formed from methoxycinnamic acid and 2-ethylhexanol, both linked to cinnamic acid chemistry. It is manufactured as a cosmetic UV-filter raw material.
History
It is a long-established and historically the most common chemical sunscreen filter. In recent years it has drawn environmental scrutiny over coral reefs: the Pacific nation of Palau enacted a 2018 law, effective in 2020, banning sunscreens containing octinoxate among other ingredients, and similar reef-protection measures have been considered elsewhere. The EU reaffirmed its permitted use limit in a 2025 safety reassessment.
Questions everyone asks
What does octinoxate protect against?
It is a UVB filter with peak absorption near 310 nm. It does not protect against UVA on its own, so it is combined with UVA filters for broad-spectrum coverage.
Why is octinoxate banned in some places?
Several jurisdictions, including Palau, restricted it over concerns about harm to coral reefs; Palau's ban took effect in 2020.
Is octinoxate photostable?
No. It degrades under sunlight, losing part of its UV-absorbing ability over time, which is why it is often paired with more stable filters.