What it is
Glyceryl isostearate is a nonionic ester formed from glycerin and the branched-chain fatty acid isostearic acid. In sunscreens and moisturizers it acts as an emollient that softens skin and as a co-emulsifier that helps disperse oils and pigments, which is useful for keeping mineral filters and tints evenly suspended. Its branched structure gives a lighter, less greasy feel than many straight-chain fatty esters.
Safety & warnings
Generally well tolerated and used at modest levels. As a fatty glyceryl ester it carries a low to moderate comedogenic potential for very acne-prone skin, though formulation context matters; it is not a recognized fragrance allergen.
Origin & sourcing
Manufactured synthetically by esterifying glycerin with isostearic acid; the feedstocks can be sourced from plant oils or produced petrochemically.
Questions everyone asks
What does glyceryl isostearate do in a sunscreen?
It works as an emollient and co-emulsifier, softening the skin feel and helping keep oils, pigments, and mineral filters evenly dispersed in the formula.
Is glyceryl isostearate the same as glycerin?
No. Glycerin is a humectant, while glyceryl isostearate is glycerin chemically bonded to isostearic acid, giving it oil-loving emollient and emulsifying properties instead.