Kojic acid is a chelation agent produced by several species of fungi, especially Aspergillus oryzae, which has the Japanese common name koji. Kojic acid is a by-product in the fermentation process of malting rice, for use in the manufacturing of sake, the Japanese rice wine. It is a mild inhibitor of the formation of pigment in plant and animal tissues, and is used in food and cosmetics to preserve or change colors of substances. It forms a bright red complex with ferric ions.


The formal discovery of kojic acid occurred in 1989, and since then, the substance has been used widely in skin care products due to its numerous benefits. Kojic acid was first extracted from mould grow on rice (Aspergillus oryzae) or that grow on soybean (Aspergillus sojae) and is used as a starter medium for the production of fermented food. In Japan, it was a by-product of the fermentation process used to produce the alcoholic beverage sake.

Nowadays, kojic acid is produced biologically by fermentation of bacteria on carbohydrates. The name is Japanese and comes from the word “koji”, which means “culture”.

The main application of kojic acid in cosmetic is as skin-lightening agent by retarding excessive melanin production.

Skin colour is determined by the quantity of melanin in the skin. Melanin is biosynthesized in the melanosome of melanocyte – a process involving the presence of the enzyme tyrosinase. Kojic acid is known to inhibit tyrosinase thereby reducing the production of melanin.

Doing so, kojic acid successfully reduces age spots and pigmentation on face and body, typically caused by sun damage. Kojic acid is also known to have an anti-microbial effect.

Prior to the discovery of kojic acid, the ingredient hydroquinone was largely the only ingredient used for skin whitening. Hydroquinone is known to cause skin irritation in many individuals, and for these people, dermatologists often recommend kojic acid as an alternative method for treating skin discoloration. Those with very sensitive skin may still develop redness or itching from the use of kojic acid, but overall, the ingredient is better tolerated than hydroquinone. The effects of kojic acid have been reported as being identical to those of hydroquinone or slightly less noticeable.

In addition to its skin-lightening abilities, kojic acid is classified as an antioxidant. This class of nutrients has the ability to counteract the effects of particles in the air called free radicals, which have the potential to cause oxidative damage to the skin cells. By limiting the effects of free radicals, kojic acid helps to prevent the formation of signs of aging that occur when the cells that produce the skin’s vital structural proteins become damaged.

Some dermatologists recommend the use of mild concentrations of kojic acid for addressing acne blemishes.

Kojic acid is also an antibacterial agent, meaning that it interferes with the processes that bacteria cells must perform to thrive and reproduce. By disrupting these processes, kojic acid causes the death of bacteria. Some dermatologists recommend the use of mild concentrations of kojic acid for addressing acne blemishes, which are often caused by bacterial infections in the pores.

Important note: The European Scientific Committee on Consumer Safety, during a re-examination of the available data for Kojic Acid, came to the conclusion that used as a skin whitening agent at a concentration of 1.0% in leave-on creams, which are generally applied to the face and/or hands, that it is safe for the consumers.