Sun filters, sunscreen and sun protection

Plenty of people use sunscreen daily without ever knowing what is doing the work. The actives are called UV filters, and they are what stands between skin and ultraviolet radiation. Nearly every sunscreen on the market blends several of them, and that is not a marketing flourish; it is a technical necessity, because no single filter absorbs evenly across the whole 290–400 nm range.

Sun protection

Before the chemistry, it is worth being precise about what sun protection buys you.

• Regular sunscreen use reduces the risk of skin cancer. It does not eliminate it, and it works alongside shade, timing and clothing rather than replacing them.
• It prevents sunburn, which is painful in itself and carries longer consequences: episodes of blistering sunburn, especially in childhood, are an established melanoma risk factor.
• There is an appearance argument too, and it is the strongest evidence-backed cosmetic case in skincare. Most visible ageing on habitually exposed skin is photo-ageing, driven largely by UV-A.
• Daily broad-spectrum use has been shown to slow the accumulation of fine lines and mottled pigmentation. It slows new damage; it does not undo what is already there.

Approved sun filters, and what "approved" covers

An approved filter is one a regulator has assessed and admitted to its positive list, at a stated maximum concentration, after safety review. Two things about those lists surprise people.

• The lists differ sharply by market. The EU permits roughly thirty filters under Annex VI of the Cosmetic Products Regulation. The US list, governed by OTC Monograph M020, is shorter. Its first new filter since the 1990s, bemotrizinol at up to 6%, was added by FDA final order OTC000039, effective 9 August 2026. Japan and Australia run their own. A filter that is routine in one market may be unavailable in another.
• Patent status is commercial, not regulatory. Filters are often described as patented or off-patent, and that does move the price: formulas built mostly on patented actives cost more, and those on established off-patent chemistry sit lower. But every filter on an approval list has cleared the same review. Where newer patented filters tend to win is photostability and breadth of coverage. That is a technical difference worth paying for, and it is separate from the patent itself.

Sunscreen lotions and creams, and country-by-country regulation

Because approval lists and maximum use levels vary, a formulator has to build to the rules of every market the finished product will reach. A formula developed against the EU annex will often need reworking for the US monograph, and a global launch usually means several closely related formulas rather than one.

Within those constraints the job is to combine filters so the absorbance curve comes out flat across both bands, and stays flat under irradiation. That is why photostable triazines such as Sunbest-BMT and Sunbest-HEB have become anchors of modern formulas, and why mineral filters like Sunbest-ZnO still earn their place. For how the bands are covered, see UV-A vs UV-B filters; for the two filter classes compared, see Chemical vs Physical sunscreens.