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Stearic Acid

Well toleratedEmulsifieremulsifieremollientthickener

No meaningful concern for most people; irritation is possible but rare.

Also written as: Octadecanoic acid

What it is

Stearic acid is an 18-carbon saturated fatty acid found in shea butter, cocoa butter and many vegetable fats, and also present in the skin's own lipids. In cosmetics it thickens the oil phase and, when neutralised with an alkali such as triethanolamine or potassium hydroxide, forms a soap-type emulsifier in situ.

What it does well

  • Thickens and stabilises creams while softening skin

    A long-established formulation staple with a very good tolerance record on intact skin.

    Strong evidence

Worth knowing

  • In soap-based formulas it contributes to an alkaline pH

    When stearic acid is neutralised into a soap, the resulting cleanser sits well above skin's natural pH, which can feel tight or drying after washing. This is a property of the soap system, not of stearic acid used simply as a thickener.

    Matters most toPeople with dry or sensitive skin using traditional soap-based cleansing products.

Where the EU stands

No specific restriction

No EU restriction on use or concentration in cosmetics.

Masks that contain Stearic Acid