Polyglutamic Acid

Polyglutamic acid is a film-forming humectant (typically used around ~0.1–1%) that primarily boosts hydration and reduces transepidermal water loss, without the keratolytic or pH-dependent activity seen with exfoliating acids. Clinical and consumer safety data generally show low rates of irritation and good tolerability, but rare stinging or redness can occur in highly compromised barriers or when layered with multiple actives, so it is best classified as very gentle rather than inert. Safety Notes: In commercial skincare, polyglutamic acid is most often used as a secondary humectant/film former at very low levels (around 0.01–0.1%) in moisturizers, toners, and rinse-off cleansers where label presence is desired without impacting viscosity or cost. Leave-on serums and hydrating gels commonly sit around ~0.1–1% active polyglutamic acid (often influenced by molecular weight and whether the supplier solution is pre-diluted). High-strength consumer-available “PGA” serums can reach about 2–3% active in leave-on products, with higher levels becoming increasingly limited by tack/film feel, stringiness, and stability/processing constraints; there is no specific EU/FDA maximum, so practical formulation limits dominate.