What is kojic acid?
Kojic acid is an organic compound with the formula HOCH2C5H2O2OH. It is a derivative of 4-pyrone that functions in nature as 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 the colors of substances. It forms a bright red complex with ferric ions.
Why Is Kojic Acid Soap Used?
Kojic acid is a skin-lightening ingredient dermatologists recommend for reducing dark spots (hyperpigmentation) and uneven skin tone. When added to soaps and cleansers, kojic acid soap is typically applied to the face or hands and washed off. Over time, using kojic acid soap may help fade sun damage, acne scars, and other hyperpigmentation.
Kojic acid has a controversial history as an ingredient in skin-bleaching products.4 Skin bleaching is a damaging practice that sets unrealistic and harmful beauty standards for people with darker skin tones. Some kojic acid soaps are still marketed for skin bleaching or "skin whitening" purposes. However, kojic acid does not bleach skin, and dermatologists recommend kojic acid for treating hyperpigmentation on darker skin tones.
kojic acid soap benefits
The benefits of using products containing kojic acid may include the following:
Anti-aging effect: Products containing kojic acid may lighten the skin, which can improve the appearance of age spots and sun damage. The reduction of dark spots can have an anti-aging effect.
Treat melasma: Kojic acid may also help decrease melasma, which is a darkening of the skin due to pregnancy.
Decrease the appearance of scars: Kojic acid may also reduce the discoloration of scars. Although the acid does not improve the thickness of scar tissue, it may reduce dark pigmentation associated with certain types of scars. Lightening the scar may make it less noticeable.
Antifungal benefits: Kojic acid is also thought to have some antifungal benefits. It may help prevent and treat certain fungal infections, such as athlete's foot and yeast infections.
Antibacterial effects: Kojic acid may also provide antibacterial benefits. It may help decrease the chances of developing common types of bacterial skin infections.
kojic acid soap side effects
In addition to the benefits, a number of adverse reactions may also be associated with kojic acid when used in cosmetic products.
Among them, contact dermatitis (especially on people with sensitive skin) is the main side effect of kojic acid. Manifestations of contact dermatitis when using kojic acid are irritation, rash, dermatitis, itching, and pain. However, these side effects can be observed in cases of improper use of kojic acid, abuse of kojic acid such as taking in concentrations higher than 1%.
Another side effect that can appear with long-term use of kojic acid is sunburn in people with sensitive skin. In addition, there is some evidence that kojic acid can also lead to skin cancer on damaged skin. However, further studies are still needed to determine other potential benefits or risks of kojic acid.
