Hydrogenated Castor Oil Isostearate

Hydrogenated castor oil isostearate is a modified plant-derived oil created by hydrogenating castor oil and converting it into an isostearate ester. This process makes it more stable and less greasy than raw castor oil, while maintaining its emollient properties.In skincare formulations, it serves dual roles: conditioning the skin surface and controlling the thickness and texture of the final product. It appears in roughly 0.1% of skincare products, typically in lower concentrations.

As an emollient, hydrogenated castor oil isostearate sits on the skin surface and fills microscopic gaps between skin cells. This can temporarily reduce water loss and create a smoother feel. Its modified structure (through hydrogenation) makes it more resistant to oxidation than unmodified oils, improving formula stability.Within the formulation itself, it adjusts viscosity—essentially thickening or thinning the product to achieve the desired texture, without requiring heavy silicones or synthetic thickeners.

This ingredient is typically part of a finished formulation rather than something used on its own. If you're using a product containing it, apply as directed by the manufacturer. It pairs well with other conditioning and hydrating ingredients, though there is no evidence it requires special timing or cannot be combined with other actives.

Hydrogenated castor oil isostearate is generally well-tolerated and recognised as safe in cosmetic use. Some sources suggest it may be slightly comedogenic or potentially problematic for fungal acne-prone skin, though formal evidence is limited; those with these concerns may wish to patch test first.