Zi
Zinc Oxide (sunscreen)
Zinc OxideSPF filter
The mineral sunscreen filter that most reliably covers both UVA and UVB. Newer, finer grinds leave less white cast.
What it does
Like chemical filters, it mostly absorbs UV instead of bouncing it back, and on its own it covers more of the UV range than any other filter.
The EU’s ingredient database lists it as a UV filter (filters UV rays), a colorant (adds color) and a bulking agent (adds volume to the product).European Commission, CosIng (© European Union, CC BY 4.0) · uses put in plain words by Drop ↗
The evidence, graded
moderateFine together — keep sunscreen alongside vitamin C, not instead of it. In one trial, an antioxidant product used with SPF 25 sunscreen cut darkening from UV more than sunscreen alone, but the antioxidant on its own did not reduce sunburn redness. The trial didn’t say which antioxidants were in the product, so it doesn’t show vitamin C does this.Wu 2011 · Clinical and Experimental Dermatology ↗
expert consensusSunscreen works best as its own film on top of moisturizer rather than mixed into it in your palm. The SPF on the label was measured on the product as sold, applied at 2 mg/cm². Blend it with something else and there is less sunscreen over the same area, so the label's number no longer describes the film. No study Drop has read measured how far the protection falls.Petersen 2014 · Photodermatology, Photoimmunology & Photomedicine ↗
expert consensusIn 2009 the SCCP considered non-nano zinc oxide (pigment grade, particles above 100 nm) safe, the phototoxicity concern not being relevant for it because it does not penetrate skin. In 2012 the SCCS found no evidence that zinc oxide nanoparticles are absorbed through skin, and concluded that nano zinc oxide up to 25% as a UV filter in sunscreens can be considered not to pose a risk after dermal application. It was of the opinion that nano zinc oxide in spray products cannot be considered safe.SCCP 2009 · European Commission SCCP (adopted 21 January 2009) ↗
emergingTitanium dioxide and zinc oxide have been considered to protect against sunburning UV by physically reflecting or scattering it. Measured with an optical integrating sphere, their average reflection across the UV range was only 4–5%, less than SPF 2. The rest of their UV protection comes from absorbing UV. At longer wavelengths, in long UVA and visible light, they mainly reflect light, up to 60%, and do not absorb it.Cole 2016 · Photodermatology, Photoimmunology & Photomedicine ↗
Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.
Pairs worth knowing
Read more
Reading the evidence · 6 minSunscreen for Aging Concerns: What a 4.5-Year Trial ShowedDaily sunscreen slowed visible skin aging in a 4.5-year randomized trial, rare evidence in skincare. What that trial shows, and what it doesn't.How Drop works · 6 minSunscreen Reapplication: Why Every 2 Hours Actually MattersSunscreen wears off faster than most people realize. What happens in those 2 hours, when reapplication matters most, and how to do it over makeup.
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