Kojic Acid (5-hydroxy-2-hydroxymethyl-4-pyrone) may be used in cosmetics to lighten the skin and to treat skin diseases like melasma. It inhibits the formation of tyrosine, the amino acid responsible for melanin production. It also treats skin conditions such as blemish scars, age spots, and sun damage. Kojic Acid is a powerful antioxidant and brightening ingredient derived from the fermentation process of certain species of Acetobacter, Aspergillus, and Penicillium. It can be used in sunscreens and after-sun products, makeup products, skin-lightening products, anti-aging products, & creams, and lotions.
Typically, Kojic acid starts showing results within two weeks. If you want to see faster results, its effects have been boosted when combined with glycolic acid or hydroquinone. Two double-blind studies concluded that combining 2% kojic acid with 2% hydroquinone with 5% glycolic acid works efficiently on pigmentation. The combinations showed visible results in 52% of cases of pigmentation. However, you should strictly avoid over dosage of kojic acid (beyond 4%) as it may lead to severe skin irritation and sensitivity.