Citric Acid

A gently exfoliating AHA that helps to remove the top layer of dead skin cells. In comparison to other AHAs, citric acid has been shown to be one of the least effective. It is also very commonly used as a stabilizing and pH-controlling agent.
Functions
Origin
Citric Acid

Overview

Citric acid is an organic acid belonging to the group of alpha-hydroxy acids (AHAs). Similar to the other AHAs, such as lactic or glycolic acid, it is an exfoliating ingredient. This means that at certain concentrations it is able to gently remove the dead skin cells from the skin’s surface, basically functioning as a gentle chemical peel.

AHAs are usually applied as superficial or medium-depth peels, like those used to treat acne, scars, roughness, age spots, and seborrhea. By removing the top layer of dead skin cells, the skin will appear more rejuvenated, smooth, and refreshed. It is a commonly recognized downside, however, that treatment by AHAs will make your skin more sun-sensitive for a short period of time.

In comparison to other AHAs, citric acid has been shown to be one of the least effective. Glycolic and lactic acid scored higher than citric acid in all measured parameters (skin cell renewal, moisturization, anti-aging properties) and were also less irritating.

Citric acid in skincare products, however, is superior as a pH stabilizer and chelating agent (chelating agents are used to bind harmful mineral ions and stabilize them in the skincare formula).

Science

1
Tang, S. C., & Yang, J. H. (2018). Dual Effects of Alpha-Hydroxy Acids on the Skin. Molecules (Basel, Switzerland), 23(4), 863.
2
Fiume, M. M., et al. (2014). Safety Assessment of Citric Acid, Inorganic Citrate Salts, and Alkyl Citrate Esters as Used in Cosmetics. International journal of toxicology, 33(2 suppl), 16S–46S.
3
Smith W. P. (1996). Comparative effectiveness of alpha-hydroxy acids on skin properties. International journal of cosmetic science, 18(2), 75–83.