What are the hazards of polyglutamic acid?

The polyglutamic acid is a cosmetic active ingredient derived from the polymerisation of an essential amino acid present in our body, L-glutamic acid. Formerly used to accelerate the healing of certain wounds and burns, the polyglutamic acid is now exploited for its moisturising properties in skin care. It works by forming a protective film on the surface of the epidermis, thus protecting it from external aggressions and limiting insensible water loss. In addition, polyglutamic acid is a polymer capable of expanding by capturing water molecules to form a network referred to as a microgel. Through this humectant mechanism, it retains water in the stratum corneum, the superficial layer of the epidermis.

The maximum concentration of polyglutamic acid is not regulated in skincare products but, generally, treatments do not contain more than 3%.

Polyglutamic acid is an active ingredient generally well tolerated, including by sensitive or reactive skin types.

Unlike other cosmetic ingredients, it is not known to irritate the skin, trigger an inflammatory response, or cause skin sensitisation. Furthermore, the high molecular weight of polyglutamic acid, combined with its polymeric structure, limits its penetration into the deeper layers of the skin, contributing to its good skin tolerance. It is indeed entirely possible to use polyglutamic acid daily. It's also worth noting that polyglutamic acid can be used during pregnancy and breastfeeding.

Several studies report that patch tests have been carried out in vivo on volunteers. More specifically, during these tests, formulations based on polyglutamic acid were applied to the skin, under occlusion, for 24 to 48 hours. The results showed an absence of irritative or allergic reaction. No erythema, oedema or itching was reported, demonstrating the good dermatological safety of polyglutamic acid. Furthermore, on a cellular level, in vitro studies have shown that polyglutamic acid is non-genotoxic, meaning it does not cause mutations or damage to the DNA of cells. This criterion is fundamental to eliminate any potential long-term risk, particularly in the context of regular cosmetic use.

Even though polyglutamic acid is a gentle active ingredient, typically well tolerated by sensitive skin, a skin reaction is always possible. To limit the risk of irritation, it is recommended to perform a tolerance test before the first use of any care product containing this ingredient. This advice applies to any new cosmetic product.

Before applying it to your entire face, we advise you to place a small amount of the treatment in the crook of your elbow or on the inside of your wrist, then let it act without rinsing. Wait 24 to 48 hours to check for the absence of signs of reaction (redness, itching, tingling). If no skin manifestation appears, you can then incorporate the product into your routine. However, in case of an immediate reaction, rinse thoroughly with clear water and discontinue use.

• Safety Assessment of Amino Acid Alkyl Amides as Used in Cosmetics. Cosmetic Ingredient Review (2013).

• ANDERSEN F. A. & al. Safety Assessment of Animal- and Plant-Derived Amino Acids as Used in Cosmetics. International Journal of Toxicology (2014).

• RADECKA I. & al.Poly-γ-glutamic acid: production, properties and applications. Microbiology Society (2015).

• YANG S.-A. & al. Gamma polyglutamic acid (gamma-pga, h form), gamma-polyglutamate hydrogels for use as super moisturizers in cosmetic and personal care products (2019).

• BARROS A. N. & al. Polyglutamate: Unleashing the Versatility of a Biopolymer for Cosmetic Industry Applications. Cosmetics (2024).