Trideceth-9

Trideceth-9 is a synthetic emulsifier belonging to the polyethylene glycol (PEG) family of ingredients. It is derived from tridecyl alcohol and ethylene oxide, and functions as a non-ionic surfactant in skincare formulations.In products, it works to stabilise emulsions by allowing water and oil components to mix evenly. This ingredient is relatively uncommon in skincare, appearing in fewer than 1 in 500 products, though it is more widely used in cosmetic and personal care applications across the industry.

Trideceth-9 is a surfactant, meaning it has a molecular structure with both water-loving and oil-loving ends. This dual affinity allows it to position itself at the boundary between water and oil phases, reducing surface tension and enabling them to blend into a stable emulsion.As a cosmetic ingredient rather than an active, it does not directly target skin concerns but instead ensures the product delivers its other actives effectively through a stable formulation.

Trideceth-9 is a formulation ingredient, not an active to be used strategically. Simply use products containing it as directed by the manufacturer. Because it is so uncommon in skincare, most users will encounter it only occasionally across different product types.

Generally well-tolerated and recognised as safe by cosmetic regulators. As with all surfactants, it is best kept away from the eye area in high concentrations, though formulated products are typically buffered to safe levels.