Glossary

Inorganic UV Filter

Written by Reviewed by the SYNC editorial team Published Last reviewed Editorial standards

Inorganic UV Filter — a mineral-based sunscreen ingredient, specifically zinc oxide or titanium dioxide, that shields skin from ultraviolet radiation. Often called physical or mineral filters, they sit largely on the skin surface and protect through a combination of absorbing, scattering, and reflecting UV light.

Key points

  • The two inorganic UV filters used in cosmetics are zinc oxide and titanium dioxide.
  • They protect by absorbing and scattering UV radiation, not solely by reflecting it as once believed.
  • Zinc oxide offers broad UVA and UVB coverage, while titanium dioxide is stronger in the UVB and shorter UVA range.
  • Mineral filters are photostable and are often chosen for sensitive or reactive skin.

Frequently asked

Do mineral sunscreens only reflect UV light?

No, zinc oxide and titanium dioxide absorb a significant portion of UV radiation as well as scattering and reflecting it, so absorption is a major part of how they work.

Why do some mineral sunscreens leave a white cast?

Zinc oxide and titanium dioxide are white and sit on the skin surface, though micronized or tinted formulations can reduce the visible cast.

Related topics

This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.

Encyclopedia

Further reading

This entry was written and checked against the sources below. They are published by clinical and scientific bodies, they are listed most readable first, and each one opens in a new tab. They are background for the whole entry rather than footnotes to individual sentences.

  1. Introduction to Sunscreens and Their UV Filters - Review of Fate, Exposure, and Effects of Sunscreens in Aquatic Environments and Implications for Sunscreen… StatPearls (NCBI Bookshelf) Reference text ncbi.nlm.nih.gov
  2. Questions and Answers: FDA posts deemed final order and proposed order for over-the-counter sunscreen U.S. FDA Regulatory and safety fda.gov
  3. Sunscreen: How to Help Protect Your Skin from the Sun U.S. FDA Regulatory and safety fda.gov
  4. Ultraviolet Filters: Dissecting Current Facts and Myths PubMed Central Peer-reviewed, open access pmc.ncbi.nlm.nih.gov
  5. Ultraviolet radiation and human health DermNet NZ Clinical guidance dermnetnz.org
  6. Ultraviolet (UV) Radiation U.S. FDA Regulatory and safety fda.gov

SYNC does not publish medical advice. Nothing here replaces a consultation with a doctor or a pharmacist about your own skin.