Trideceth-5

Trideceth-5 is a synthetic surfactant derived from tridecyl alcohol, a fatty alcohol combined with ethylene oxide. It belongs to the polyethylene glycol (PEG) family of emulsifiers, which are widely used in cosmetic formulations to stabilise mixtures of ingredients that would otherwise separate.In skincare products, its primary role is functional rather than active. It allows formulators to combine oils, silicones, and water-based components into a stable, homogeneous product—whether that is a lotion, serum, or cream. Without emulsifiers like this, your moisturiser would eventually separate…

Trideceth-5 is an emulsifier, meaning it has a dual nature: one end of the molecule is attracted to oil, whilst the other is attracted to water. By positioning itself at the interface between these two immiscible substances, it prevents them from separating and keeps the formulation stable.From a skin perspective, it does not penetrate deeply or provide direct therapeutic benefits. Instead, it serves a structural role—ensuring that the skincare product remains homogeneous and that its other ingredients can be delivered effectively.

There is no special usage guidance for this ingredient. It is present in finished formulations at low concentrations and requires no specific application technique. Simply use the product as directed by the brand.

Trideceth-5 is generally well-tolerated and is approved for use in cosmetics across major regulatory bodies including the EU and the US. Whilst allergic contact dermatitis is rare, those with known sensitivity to PEG-based ingredients should check the full ingredient list before use.