Citric Acid

Citric acid is an extract derived from citrus fruits and is primarily used in small amounts to adjust the pH of products to prevent them from becoming too alkaline.
Citric acid is an alpha hydroxy acid (AHA) and as such, in the right formula and concentration, it can exfoliate the skin. However, research into this ability has so far looked at much higher concentrations (20%, for example) than are typically used in skin care products – not to mention that there is proportionately more research into the AHAs glycolic and lactic acids. In addition, the AHAs lactic and glycolic acid have been shown to be more effective and less likely to promote a stinging reaction on the skin.