Kojic Acid

Fungal-derived tyrosinase inhibitor that fades hyperpigmentation and dark spots.

Also known as: 5-hydroxy-2-hydroxymethyl-4H-pyran-4-one, kojic acid dipalmitate, Same name.

What it is

Kojic acid is a naturally occurring organic compound produced by certain fungi (notably Aspergillus and Acetobacter species) during fermentation. It's a small-molecule tyrosinase inhibitor that disrupts melanin synthesis at the enzyme level.

What it does

Kojic acid works by inhibiting tyrosinase, the enzyme responsible for converting the amino acid tyrosine into melanin. This reduces melanin production in melanocytes, leading to gradual fading of hyperpigmentation, age spots, melasma, and post-inflammatory hyperpigmentation. Results typically appear over 4–12 weeks of consistent use.

The evidence

Strong clinical evidence supports kojic acid's efficacy for melasma and post-inflammatory hyperpigmentation, with multiple controlled trials showing 20–40% improvement in pigmentation over 8–12 weeks. Moderate evidence exists for general brightening; it is less potent than hydroquinone but better tolerated.

Best for

Melasma, post-inflammatory hyperpigmentation, age spots, and uneven skin tone in all skin types, especially darker skin tones where irritation from stronger depigmenting agents is a concern.

Pairs well with

Niacinamide, vitamin C, glycolic acid, azelaic acid, and sunscreen (essential). Works synergistically with other tyrosinase inhibitors like arbutin or licorice extract.

Use cautiously with

Avoid combining with hydroquinone at high concentrations without professional guidance, as stacking depigmenting agents increases irritation risk. Use cautiously with strong exfoliants (retinoids, AHAs) in the same routine initially.

Cautions

Kojic acid can cause contact dermatitis and sensitization in 1–2% of users; patch test first. May increase photosensitivity slightly; daily SPF 30+ is mandatory. Generally safe in pregnancy, but consult a provider. Avoid if allergic to fungi or fermented products.