Zinc Oxide

Zinc oxide is a mineral UV filter that physically sits on the skin and reflects/scatters sunlight — one of the most trusted sunscreen ingredients in dermatology, in a sunscreen launching this October.

Description

What is it?

Zinc oxide is a naturally occurring mineral compound used as a “physical” or “mineral” UV filter. Instead of absorbing UV rays the way chemical filters do, tiny zinc oxide particles sit on top of the skin and physically reflect and scatter both UVA and UVB rays before they reach living skin cells.

What does it actually do?

Broad-spectrum efficacy is well established across decades of formulation science. According to PubMed, a critical review of zinc oxide’s optical and structural properties in sunscreens (Cavalcanti IMGA et al. “Optical and structural properties of sunscreens evaluated by physical techniques with emphasis on zinc oxide: A critical review.” Applied Radiation and Isotopes, 2025) describes zinc oxide as “a prominent inorganic UV filter due to its broad-spectrum efficacy, photochemical stability, and biocompatibility,” making it one of the most reliable single filters available for both UVA and UVB protection. (DOI)
Combining zinc oxide with complementary filters can substantially raise a formula’s measured SPF. According to PubMed, an in vitro photoprotection study (Machado GT et al. “In vitro photoprotective efficacy and photostability of synthesized star-shaped ZnO nanoaggregates associated with ethylhexyl methoxycinnamate and butyl methoxydibenzoylmethane.” Journal of Photochemistry and Photobiology B: Biology, 2024) found that combining zinc oxide with two organic UV filters increased measured in vitro SPF from 26 to 285 in lab testing, and the combination retained a broad-spectrum profile (SPF >15, critical wavelength >370nm) even after photostability testing. (DOI)

(Note: both citations are physicochemical/in vitro studies measuring UV-blocking performance in lab conditions, not human clinical trials of a finished product. Zinc oxide’s mechanism and safety profile are extremely well established through decades of regulatory and formulation science.)

Who is it good for?

Everyone — daily sunscreen use is recommended for all skin types, especially sensitive and acne-prone skin, since mineral filters are generally better tolerated than some chemical filters.

No real precautions, though mineral sunscreens can leave a mild white cast on deeper skin tones depending on the formula’s particle size and finish.

How Mystic Dust uses it

Daily Defence Sunscreen, as one of its core mineral UV filters.

Pairs well with

Chemical UV filters, Ferulic Acid, Green Tea — the antioxidant and next-gen filter combination formulated into the same upcoming sunscreen.

Use with caution alongside

Nothing specific — zinc oxide is broadly compatible with other sunscreen actives.

Research & Findings

According to PubMed: -

Cavalcanti IMGA, Valeriano CCS, Marçal AC, de Lima Ferreira Novais A, do Nascimento Souza D. “Optical and structural properties of sunscreens evaluated by physical techniques with emphasis on zinc oxide: A critical review.” Applied Radiation and Isotopes, 2025;226:112217. DOI

Machado GT, Chiabai CR, Pinheiro MS, Pinto CASO, Baby AR, Andrade GRS, Pessoa FVLS. “In vitro photoprotective efficacy and photostability of synthesized star-shaped ZnO nanoaggregates associated with ethylhexyl methoxycinnamate and butyl methoxydibenzoylmethane.” Journal of Photochemistry and Photobiology B: Biology, 2024;261:113068. DOI