UV filters in the Youlief sunscreens

How filter selection works

A sunscreen needs coverage across UVB (290 to 320 nm) and UVA (320 to 400 nm), and it needs that coverage to survive sun exposure. No single organic filter does both well while remaining photostable, so broad-spectrum products combine filters - some primarily UVB, some UVA, some acting as photostabilisers for the others. The three Youlief sunscreens use seven filters between them, all from the newer generation of photostable organics.

The filters used

Ethylhexyl triazone (Uvinul T 150) - a highly efficient UVB filter with strong photostability and very low skin penetration due to high molecular weight. Present in all three products.

Diethylamino hydroxybenzoyl hexyl benzoate (Uvinul A Plus) - a UVA filter, photostable, covering the longer UVA I range. All three products.

Methylene bis-benzotriazolyl tetramethylbutylphenol (Tinosorb M) - unusual in working by absorption, scattering and reflection, and acting as a broad-spectrum filter and photostabiliser. Two products.

Diethylhexyl butamido triazone (Uvasorb HEB) - a UVB filter with high efficiency per unit weight. Two products.

Bis-ethylhexyloxyphenol methoxyphenyl triazine (Tinosorb S) - broad-spectrum, and a strong photostabiliser for other filters. Aqua Sun.

Terephthalylidene dicamphor sulfonic acid (Mexoryl SX) - a water-soluble UVA filter, notable for sitting in the aqueous phase where most filters are oil-soluble. Aqua Sun.

Polysilicone-15 (Parsol SLX) · a polymeric UVB filter; its high molecular weight means it stays on the surface and does not penetrate. Aqua Sun.

A regulatory note that matters

Several of these filters are approved in the EU, Korea, Japan and Australia but not in the United States, where sunscreen actives are regulated as over-the-counter drugs and the approved list has changed little in decades. This is why sunscreen formulations differ so markedly by market, and why a product legal in one region cannot simply be sold in another. Any statement about filter approval must be jurisdiction-specific.

What sunscreen ingredient pages should not do

They should not rank filters against each other on safety, since the evidence rarely supports confident ordering. They should not imply that high molecular weight guarantees zero penetration. And they should not present SPF as the whole picture, since UVA protection is a separate measure with its own regional testing standards.