Kojic Acid



Kojic Acid description

By-product of the fermentation process of malting rice for use in the manufacture of sake (Japanese rice wine). In vitro and in vivo research and animal studies have shown that kojic acid is effective for brightening an uneven skin tone. Kojic acid’s downside is that it’s an extremely unstable ingredient in cosmetic formulations. On exposure to air or sunlight, it turns brown and loses its efficacy. Many cosmetics companies use kojic dipalmitate as an alternative because it’s more stable in formulations. However, there’s no research showing that kojic dipalmitate is as effective as kojic acid, although it’s a good antioxidant.

Kojic Acid references

  • International Journal of Molecular Sciences, September 2009, pages 4,066-4,087
  • Journal of Cosmetic Science, March-April 2004, pages 139-148
  • Journal of Dermatological Science, May 2003, pages 193-201
  • The Journal of Pharmacy and Pharmacology, December 1994, pages 982-985

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