Po
Polyhydroxystearic Acid
Polyhydroxystearic Acid
Coats mineral particles like zinc and titanium dioxide so they spread into an even film instead of clumping or streaking.
What it does
It coats mineral particles, like the zinc oxide and titanium dioxide in mineral sunscreens and the pigments in makeup, so they stay separate and spread into a smooth, even layer instead of clumping or streaking. It helps a product apply well; it doesn’t act on skin.
The evidence, graded
expert consensusUS safety reviewers (2026) assessed polyhydroxystearic acid with two other polymers. Products use it to help solid particles spread evenly, without it being a surfactant. They judged all three safe as used.Raj 2026 · International Journal of Toxicology ↗
Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.
Also known as
PHS
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