kojic

Kojic acid is a naturally occurring organic compound used primarily as a skin-lightening agent in cosmetic products. It is produced by several species of fungi, most notably Aspergillus oryzae, during fermentation processes such as those used to make sake, miso, and soy sauce. The substance is also found in certain mushrooms and other fungal sources.

In cosmetics, kojic acid acts mainly by inhibiting tyrosinase, the enzyme that drives melanin production in pigment cells. By reducing tyrosinase activity, it can help lighten hyperpigmented areas and even skin tone. Kojic acid is commonly formulated in topical creams, serums, and masks, typically at concentrations around 1% or less, though some markets permit higher levels. To address stability and penetration, esters such as kojic acid dipalmitate are also used in formulations.

Safety and regulation vary by country. Kojic acid can cause skin irritation or allergic contact dermatitis in sensitive individuals and may increase photosensitivity, so sun protection is recommended during use. Regulatory status is not uniform; many cosmetic guidelines restrict concentrations and require clear labeling. Long-term safety data are limited, and some authorities advise cautious use, particularly on broken or inflamed skin or with prolonged application.

Alternatives and considerations include other lightening agents such as hydroquinone, azelaic acid, niacinamide, vitamin C, and retinoids. Users with persistent or extensive hyperpigmentation should consult a dermatologist to determine appropriate treatment options.