Ingredient dictionary

Polyhydroxystearic Acid

Polyhydroxystearic Acid is a fatty-acid-based polymer made from castor-oil-derived building blocks. It mainly helps spread and hold pigments and oils evenly in a formula. It is on the label of 16 products in our library. Checked against our library November 6, 2026.

The catch: none for most people; check the full product list if your skin reacts easily.

What Polyhydroxystearic Acid does

Disperses pigments evenly through oils
Stabilizes oil and water mixtures
Helps products spread smoothly

Polyhydroxystearic Acid is built from hydroxystearic acid, a fatty acid that comes from castor oil. Its molecules link together into a longer chain, so it is a polymer. Part of each molecule is comfortable in oils, and part can grip pigment particles or water. That mixed nature lets it act as a bridge between ingredients that would otherwise separate.

Formulators use it mainly as a dispersing agent and emulsifier. It coats powder pigments so they spread through oils without clumping, which helps shades look smooth and even. In some creams, it helps oil and water stay mixed. Products made with it usually feel smooth and spread easily on the skin.

Good for

Well suited to pigment-rich products like eyeshadow, lip gloss, brow products and self tanners, where even color matters.

Be careful if

Nothing in particular for most skin types.

Frequently asked questions

Is Polyhydroxystearic Acid safe for skin?

It is generally well tolerated and is used in many makeup and skincare products. Like any ingredient, a person with a specific sensitivity could react, so patch testing a new product is a sensible habit. If you have a known reaction to castor-derived ingredients, ask a dermatologist first.

Is Polyhydroxystearic Acid vegan?

It is made from castor oil, a plant-derived starting material. Whether a specific product is vegan depends on all of its other ingredients and how it is made, so check that product's full label or the brand's own statement.