Kosé Suncut UV Perfect Gel SPF 50+ Versus Isntree Hyaluronic Acid Airy Sun Stick SPF50+ PA++++

DHHB has been approved by the EU, Japan, Taiwan, and South America for use up to 10%. Unfortunately, it has not been approved for use in the US or Canada due to slow regulatory processes.

This ingredient is soluble in oils, fats, and lipids.

In formulas, it's always paired with a separate UVA filter because octinoxate solely protects skin from UVB.

Because it's an oil-soluble liquid, it's easy to blend into the oil phase of lotions/creams and gives a cosmetically elegant feel.

The one quirk about formulating this ingredient is photostability; the molecule slowly changes shape into a less effective version when sunlight hits it. So the longer you're in the sun, the weaker its protection gets. The drop can be more than 30% in some formulas.

It also doesn't play nice with Avobenzone (the common UVA filter) since avobenzone destabilizes octinoxate and the two degrade each other. But don't worry: brands have solved this issue by adding photostabilizers like Tinosorb S to prevent degradation and keep SPF stable under heavy UV exposure.

The maximum allowed level is 10% in the EU and Australia, 7.5% in the US and Canada, and 20% in Japan.

The Cosmetic Ingredient Review Panel has concluded this ingredient to be safe in cosmetics up to 10%.

One last thing worth knowing for context:

Octinoxate has been the subject of ongoing review in Europe where the Scientific Committee on Consumer Safety's (SCCS) 2025 final opinion is that this ingredient is an endocrine-active substance.

Lab and animal studies suggest it can act a bit like a hormone in the body (mildly mimicking estrogen and slightly blocking male hormones). It's important to know this hasn't really been shown to happen in everyday human use.

This ingredient is also banned in Hawaii over coral reef concerns.

The unique structure of silica enhances the spreadability and adds smoothness, making it a great texture enhancer.

It is also used as an active carrier, emulsifier, and mattifier due to its ability to absorb excess oil.

In some products, tiny microneedles called spicules are made from silica or hydrolyzed sponge. When you rub them in, they lightly polish away dead skin layers and enhance the penetration of active ingredients.

Interestingly, the size of the molecule affects its behavior:

Some clinical evidence links low molecular weight versions to improved wrinkle depth, elasticity, anti-inflammatory effects, and barrier repair.

Many serums use a blend of both weights so you can get surface hydration plus longer-lasting and deeper effects.

You'll typically see concentrations between 0.1-2% for this ingredient.

You'll also recognize water as that liquid we all need to stay alive. If you see this, drink a glass of water. Remember to stay hydrated!