What is kojic acid?
Kojic acid is a naturally derived compound produced during the fermentation of rice and certain fungi (notably in the production of sake and soy sauce). It works by chelating (binding to) copper at the active site of tyrosinase, the enzyme melanocytes need to produce melanin — effectively blocking pigment production at its source.
It is used in serums, creams, and professional peel formulations, typically at concentrations of 1–4% for at-home use. Higher concentrations used in professional settings are applied and monitored by a practitioner given the increased potential for irritation at higher strengths.
Effectiveness and who should be cautious
Kojic acid has a long track record of clinical use for melasma, sun spots, and post-inflammatory hyperpigmentation, often used in combination formulations alongside other tyrosinase inhibitors such as tranexamic acid or azelaic acid for a stronger combined effect than any single ingredient alone.
It carries a higher risk of contact irritation and, in some individuals, sensitisation compared to gentler options like niacinamide. For sensitive skin, rosacea-prone skin, or those new to active ingredients, Dr. Bangalee often recommends starting with a gentler tyrosinase inhibitor and introducing kojic acid later if needed.