Benzophenone-4
Explained
Benzophenone-4 (aka Sulisobenzone) is a water-soluble UV filter that mainly absorbs UVB rays with some UVA coverage.
It has two jobs in a formula:
- It adds sun protection
- It acts as a photostabilizer that keeps the rest of the product from breaking down in light
That's why you'll spot it in a variety of products from sunscreens to clear-packaged serums where it protects dyes, fragrances, and other actives from degrading.
As a UV filter, it is fairly weak on its own. This is why it's almost always paired with stronger UV filters to build up SPF.
On the regulatory side, this ingredient is well-studied and broadly considered safe as used.
The EU's Scientific Committee on Consumer Safety reviewed it (and the endocrine-disruption questions that had been raised) and concluded it's safe as a UV filter up to 5%.
The US and Canada allow up to 10% and the CIR Expert Panel has found benzophenones safe at cosmetic-use levels with low skin penetration.
The only thing worth flagging for is contact allergy:
Benzophenone-4 stands out among UV filters as a frequent trigger or allergic and photoallergic contact dermatitis. A 2007 study in Contact Dermatitis even called it an "emerging allergen" so a small subset of people may get redness or irritation from it.
See all 740 products with Benzophenone-4
