PCA at a glance

  • Humectant derived from amino acids
  • Increases water content (hydration) in the uppermost layers of skin
  • Also part of skin’s natural moisturising factor
  • Often linked with mineral electrolytes to further supercharge hydration within skin’s aquaporins

PCA description

PCA (which stands for pyrrolidone carboxylic acid) is an amino acid-derived ingredient that functions as a humectant. As such, it increases water content (hydration) in the uppermost layers of skin. It is also part of skin’s intercellular matrix and plays an influential role in what’s known as skin’s natural moisturising factor. This makes PCA a skin care ingredient that skin readily recognizes and knows how to utilise. Several mineral-based derivatives of PCA are used in skin care, including sodium PCA, calcium PCA, magnesium PCA, and potassium PCA. Linking these mineral electrolytes with PCA allows them to work within skin’s aquaporins (water channels) to enhance hydration and train skin to maintain its moisture balance. This also helps strengthen skin’s barrier. PCA has been deemed safe by the Cosmetic Ingredient Review Expert Panel. Their report surveyed products containing between 0.000012-1.9% PCA.

PCA references

  • International Journal of Toxicology, 2019, pages 5S-11S
  • International Journal of Cosmetic Science, February 2017, pages 2-10, and December 2016, pages 567-575
  • Journal of Dermatological Science, December 2014, pages 231-239

Peer-reviewed, substantiated scientific research is used to assess ingredients in this dictionary. Regulations regarding constraints, permitted concentration levels and availability vary by country and region.

Ingredient ratings


Proven and supported by independent studies. Outstanding active ingredient for most skin types or concerns.


Necessary to improve a formula's texture, stability, or penetration.


Generally non-irritating but may have aesthetic, stability, or other issues that limit its usefulness.


There is a likelihood of irritation. Risk increases when combined with other problematic ingredients.


May cause irritation, inflammation, dryness, etc. May offer benefit in some capability but overall, proven to do more harm than good.


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Not Rated