PEG-9

PEG-9 is a polyethylene glycol, a type of polymer derived from petroleum. It functions as both a humectant—a substance that draws water into the skin—and a solvent, helping other ingredients dissolve and mix evenly within formulations.In skincare products, PEG-9 serves a primarily functional role rather than delivering active benefits on its own. It is commonly used in serums, creams and lotions to improve texture, stability and the delivery of other actives.

PEG-9 is hygroscopic, meaning it has a strong affinity for water molecules. When applied to skin, it draws moisture upward from the dermis and binds water from the air, keeping it at the skin's surface longer than it would otherwise remain.As a solvent, PEG-9 also dissolves ingredients that might otherwise be poorly miscible, allowing formulators to create stable, homogeneous products that feel pleasant to apply.

PEG-9 works best as part of a formulation rather than as a standalone treatment. For optimal hydration, use products containing PEG-9 on damp skin—this maximises the humectant effect by providing moisture for the ingredient to bind. In very dry climates, follow with an occlusive moisturiser to seal in hydration.

PEG-9 is generally well-tolerated and considered safe for use in cosmetics. Rarely, some individuals may experience sensitivity; discontinue use if irritation occurs.