Polysorbate 21

Polysorbate 21 is a nonionic surfactant derived from sorbitol and oleic acid. It belongs to the polysorbate family of emulsifiers, which are widely used in skincare to blend ingredients that don't naturally mix — such as oils and water. In cosmetic formulations, it helps create stable emulsions, suspensions and solutions.As an emulsifying agent, polysorbate 21 works by positioning itself at the interface between oil and water phases, allowing these otherwise incompatible substances to remain evenly distributed throughout a product.

Polysorbate 21 is an amphiphilic molecule, meaning it has both water-loving and oil-loving regions. It migrates to the boundary between oil droplets and the surrounding water phase, creating a protective layer that prevents the droplets from coalescing and separating out.This stabilising action is particularly useful in nano-emulsions and other fine dispersions, where maintaining uniform particle size is important for both product stability and skin feel.

Polysorbate 21 is a formulation ingredient rather than an active treatment, so there is no specific usage guidance for consumers. It is typically used at low concentrations within finished products. If you are using a product containing polysorbate 21, follow the standard application instructions provided by the manufacturer.

Polysorbate 21 is generally well-tolerated and widely used in cosmetics and pharmaceutical products. Some individuals with sensitivities to surfactants or oleic acid may experience irritation; patch testing is advisable if you have known surfactant sensitivity.