PEG-4
PEG-4, also called polyethylene glycol 4, is a short polyether made from ethylene oxide units. The number 4 refers to an average of four units in the chain, not to four separate ingredients; PEG-4 is therefore not one molecule with one fixed chain length.
PEG-4: what it is
PEG-4, also called polyethylene glycol 4, is a short polyether made from ethylene oxide units. The number 4 refers to an average of four units in the chain, not to four separate ingredients; PEG-4 is therefore not one molecule with one fixed chain length.
That detail distinguishes it from other numbered polyethylene glycols. A material labelled PEG-4 can contain chains with two to eight ethylene oxide units, whereas PEG-6 or PEG-8 refer to higher averages. It is an industrially made material rather than a plant extract or oil, and it is used where a formula needs to handle components that mix with water.
PEG-4: what it does in cosmetics
In cosmetics, PEG-4 is used as a humectant and a solvent. As a humectant, it helps the formula hold water; as a solvent, it helps dissolve or distribute other components. In everyday terms, this can support an even texture and help water-soluble ingredients be incorporated into the product, without by itself proving that the product treats dry skin.
A safety review also records PEG-4 use in nail preparations and observed use concentrations in that category. Its toxicology evidence includes oral studies in rats and laboratory tests; those studies do not measure improvements in hydration, acne, wrinkles, or dark spots in people using a cosmetic. Its place on a label therefore explains a formulation role, not a clinical-result promise.
PEG-4: conditions and care
The Cosmetic Ingredient Review advises that PEG-4 should not be used on damaged skin. This advice relates to reports of systemic toxicity and contact dermatitis in burn patients who used a PEG-based topical ointment.
Products containing this ingredient
See which products include it and the name used in each composition.
