Ethylhexyltriazone is a synthetic sunscreen ingredient known for its excellent ability to help protect the skin from UVB rays. It is not currently approved as a sunscreen agent in the United States and Canada, but is available in other markets in up to 5% concentration.
Ethylhexyltriazone provides maximum protection at 314nm within the UVB spectrum. As such, it must be combined with other sunscreen agents to achieve optimal broad-spectrum protection. It helps increase the photostability of other UV filters such as avobenzone.
Ethylhexyltriazone's insolubility in water makes it favorable in water-resistant formulations. On the flip side, it can be difficult to formulate with in water-based formulas; however, chemists have found ways around this by developing unique delivery systems, including encapsulation methods.
It should be noted that researchers point out that ethylhexyl triazone's high molecular weight (823.07 g mol−1) limits its penetration. This is a good thing, as you want your sunscreen ingredients to stay in the top layers of the skin where they can best provide a first line of defense against harmful UV rays. Limiting the penetration of UV filters like this also reduces the risk of experiencing a sensitized reaction. https://www.paulaschoice.com/ingredient-dictionary/ingredient-ethylhexyl-triazone.html?q=Ethylhexyl%20Triazone&fdid=ingredients