Diethylhexyl Butamido Triazone

Diethylhexyl Butamido Triazone (aka Iscotrizinol) is an oil-soluble organic UV filter that mainly absorbs UVB and a bit of UVA II light.

This ingredient is great at preventing sunburn but doesn't cover the deep UVA I range. This is why it's often paired with a UVA filter like Avobenzone or Bemotrizinol.

Two of its biggest selling points are efficiency and stability:

1. It delivers high SPF at low use levels (~SPF 12.5 at maximum allowed concentration 10%)
2. It's one of the most photostable filters out there and only loses about 10% SPF protection after 25 hours of sun exposure.

Most of the other chemical filters are considered "photostable" if they can last for two hours.

Because this ingredient is oil-loving, it can sit neatly into the oil phase of emulsions and shines in water-repellent/water-resistant formulations.

The EU and Canada allow it to be used up to 10% and Japan allows it up to 5%.

Unfortunately, it's not yet an FDA approved sunscreen agent so you won't be able to find it in sunscreens in the US.

Safety-wise, it has a pretty solid record: the EU's Scientific Committee on Consumer Safety (SCCS) has reviewed it and found low skin absorption, no capacity to produce skin irritation or photo-irritation.

In vitro testing has found less than 0.1% of the applied dose is absorbed by the skin over 24 hours (mostly due to its large molecule size).

Fun fact: This ingredient even has anti-inflammatory properties similar to those of ketoprofe, an anti-inflammatory medication.