What Is It?

In cosmetics and personal care products, PCA (pyrrolidonecarboxylic acid) is used mostly in the formulation of hair conditioners and moisturizers. The sodium salt of PCA, Sodium PCA, can be found in these products, as well as in shampoos, hair sprays, permanent waves, skin fresheners and other hair and skin care products.

Why Is It Used?

PCA and Sodium PCA increase the water content of the top layers of the skin by drawing moisture from the surrounding air. They also enhance the appearance and feel of hair, by increasing hair body, suppleness, or sheen, or by improving the texture of hair that has been damaged physically or by chemical treatment.

Scientific Facts

PCA, also known pyroglutamic acid or pidolic acid, occurs naturally in mammalian tissues, including the skin. It can be prepared from glutamic acid, an amino acid found in vegetables, fruits, grasses and molasses.

Safety Information

The safety of PCA and PCA salts has been reviewed by the Cosmetic Ingredient Review (CIR) Expert Panel on several occasions. In 1999, the Expert Panel reviewed available safety data for PCA and sodium PCA and concluded these ingredients are safe as used.

In 2014, in accordance with CIR procedures, the Expert Panel reassessed the safety of PCA, sodium PCA and three additional PCA salts (calcium PCA, magnesium PCA and potassium PCA). The Expert Panel found the data included in the original 1999 safety assessment also supported the safety of the calcium, magnesium and potassium salts of PCA as used in cosmetics. Based on its review of all available scientific data, the Panel concluded the following 5 ingredients are safe in cosmetics and personal care products in the present practices of use and concentration. 

  • PCA (2-pyrrolidone-5-carboxylic acid)
  • Sodium PCA
  • Calcium PCA
  • Potassium PCA
  • Magnesium PCA

In addition, as in the 1999 safety assessment, the Expert Panel recommended that PCA and its salts should not be used in products in which N-nitroso compounds (i.e., nitrosamines) can be formed.

CIR Safety Review: The CIR Expert Panel noted that a manufacturer of these ingredients recommended a concentration range of 0.2-4% in cosmetics and personal care products. PCA applied to the skin was absorbed to a limited extent. Absorption was in addition to PCA already present in the skin. In short-term and subchronic studies, findings were unremarkable.

Sodium PCA was nonirritating to the eye and skin at concentrations up to 50%. No evidence of phototoxicity, sensitization or comedogenicity was found. These ingredients were not genotoxic. In a range of clinical tests, PCA and Sodium PCA were found to be nonirritating and nonsensitizing (with and without UV exposure). Based on the low skin penetration of dermally applied PCA and in recognition that PCA is a normal component of the skin, it was considered that reproductive and developmental toxicity data were not critical to completion of the safety assessment.

These ingredients, however, should not be used in cosmetics and personal care products containing nitrosating agents.

More information about nitrosamines.

PCA and Sodium PCA may be used in cosmetics and personal care products marketed in Europe according to the general provisions of the Cosmetics Regulation of the European Union.

Link to the EU Cosmetic Regulation:

More Scientific Information

PCA is a cyclic organic compound, and Sodium PCA is the sodium salt of PCA. In cosmetics and personal care products, they both function as hair conditioning agents and skin conditioning agents – humectant. These hygroscopic materials also retard moisture loss from products during use.


Find out more about the regulation of Food Additives by the Food and Drug Administration

Food Ingredients and Packaging: http://www.fda.gov/Food/IngredientsPackagingLabeling/default.htm

Food Contact Substances: http://www.fda.gov/Food/IngredientsPackagingLabeling/PackagingFCS/defaul…

Substances Generally Recognized As Safe (GRAS): http://www.fda.gov/Food/IngredientsPackagingLabeling/GRAS/default.htm

Search the Code of Federal Regulations http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm

EU Cosmetics Inventory http://ec.europa.eu/consumers/cosmetics/cosing/