Trihydroxystearin

Trihydroxystearin is a fatty acid derivative—a type of emollient and viscosity controlling agent used in skincare formulations. It is derived from stearic acid, a naturally occurring fatty acid found in plant and animal sources, and is modified to include three hydroxyl groups, which alter its properties and behaviour in a formula.In a skincare product, trihydroxystearin serves two main functions: it conditions the skin surface by depositing a light occlusive layer, and it thickens the product to achieve the desired consistency. It is found in approximately 1.3% of skincare products on the …

Trihydroxystearin works by sitting on the skin's surface, where its fatty acid structure allows it to interact with the skin's natural oils and create a thin, breathable occlusive layer. This layer helps to slow down water loss from the skin without clogging pores or creating a heavy, waxy feeling.In formulations, the hydroxyl groups in its structure make it an effective thickener—it increases viscosity and helps stabilise emulsions and suspensions, ensuring the product maintains the right texture from manufacture through to use.

Trihydroxystearin is a supporting ingredient rather than an active one, so it works best as part of a complete skincare routine. It is typically found in moisturisers, serums, and body care products. Use as directed by the product instructions—most products containing this ingredient are applied once or twice daily to cleansed skin.

Trihydroxystearin is generally well-tolerated and is approved for use in cosmetics in major regulatory regions. Some users sensitive to fatty acid esters or those prone to fungal acne may wish to patch test first, as fatty acid derivatives can occasionally trigger sensitivity in susceptible individuals.