Sodium Polyglutamate

Sodium polyglutamate is a film-forming humectant/skin-conditioning polymer typically used at low levels (about 0.1–2%) to improve hydration and feel, and it is generally well tolerated in patch testing with low rates of irritation. It is not pH-active and doesn’t have the barrier-disruptive behavior seen with acids, alcohols, or strong surfactants. Rare stinging can occur on severely compromised or post-procedure skin due to osmotic effects or formulation context, so I score it as very gentle rather than inert. Safety Notes: In commercial skincare, sodium polyglutamate is most often used as a humectant/skin-conditioning polymer at low levels (~0.01–0.3%) in both rinse-off cleansers and leave-on lotions/serums to boost hydration and improve feel. Higher levels are found in consumer-available high-hydration gel serums, sheet mask essences, and polymer-thickened “plumping” treatments where it can function as a primary moisturizing film former and viscosity builder (commonly ~0.5–2%), with the upper end around ~3% observed in specialty leave-on concentrates; above this, texture and tackiness typically become limiting.