Regimen Lab Skincare Encyclopedia ?

Sodium PCA

*Preliminary Lab Notes* - Full Entry Under Development

Ingredient Profile

Common Name: Sodium PCA
INCI: Sodium PCA
Source: Chemically Synthesized
Sodium PCA Molecule

kligman ingredient evaluation

Penetration: Under analysis
Biochemical Mechanism: Under analysis
Level of Evidence: Under analysis

Regimen's Take

Sodium PCA is one of the most abundant components of the skin's Natural Moisturizing Factors (NMFs), comprising about 12%. It's a powerful humectant, with greater moisture binding capacity than Sodium Lactate and Glycerin. Its humectant properties and ability to be readily absorbed by the skin make it an excellent component in skincare products. Those with dry skin in particular should look for Sodium PCA, typically as part of hydration serums or moisturizers.


  • Look for Sodium PCA in concentrations of 2% - 5%, as it has been shown to have it's optimal hydrating effect at these levels
  • The best products will combine Sodium PCA with other NMFs

The full Regimen Lab Skincare Encyclopedia Entry for Sodium PCA is in development. Check back in a few weeks for an update!

What is Sodium PCA?

PCA is the cosmetic ingredient term used for the cyclic organic compound known as 2-pyrrolidone-5-carboxylic acid. The sodium salt is a naturally occurring humectant in the stratum corneum at levels about 12% of the Natural Moisturizing Factor (1) corresponding to about 2% by weight in the stratum corneum (2). The sodium salts of PCA are among the most powerful humectants.

What are its benefits to the skin and how is it used it the cosmeceutical industry?

Sodium PCA is a humectant that has high water absorbing properties and binds moisture to cells, and hold several times its weight in water.  It is also considered to be hygroscopic, which means that it has the ability to absorb moisture from the air. 

Among its many functions is that it delivers moisture to the hair and skin, and is often seen as an emollient or humectant in hair conditioners and moisturizers. It is also used as an ingredient in shampoos, hair sprays, permanent waves, skin fresheners and other hair and skin care products. 

Clinical Studies 

A study wherein treatment with  a  cream  containing  5%  sodium-PCA  also  increased  the  water-holding  capacity  of isolated  corneum  compared  with  the  cream  base  (3).  The  same  cream  was  also  more effective than a control product containing no humectant, and equally effective as a similar established  product  with  urea  as  humectant,  in  reducing  the  skin  dryness  and  flakiness. 

1 Jacobi O. Moisture regulation of the skin. Drug Cosmet Ind 1959; 84:732–812.

2 Laden K, Spitzer R. Identification of a natural moisturizing agent in skin. J Soc Cosmet Chem

1967; 18:351–360.

3 Middleton JD, Roberts ME. Effect of a skin cream containing the sodium salt of pyrrolidone

carboxylic acid on dry and flaky skin. J Soc Cosmet Chem 1978; 29:201–205.

4 Ajinomoto Co., Inc. 1994b. Supplementary safety evaluations on animals. Technical Bulletin AJD-8002.

5 Usines Chimiques D’lvry-la-Bataille (UCIB). 1987. Comedogenic capacity ofpyrolidone carboxylate sol aquesuse 50%.

*more related studies:

The Skincare Encyclopedia aims to improve public understanding of the biology and chemistry of skincare. The Encyclopedia is rooted in core scientific principles and extensive research, in many cases in collaboration with the authors of the original studies referenced. This is a project of Regimen Lab, maintained by a group of multidisciplinary scientists, MDs, and researchers.