Kojic Acid

Also known as: tyrosinase-inhibiting depigmenting agent

Hair RestoreDermatology

In plain English

Kojic acid is a naturally derived skin-lightening ingredient used to fade dark spots, melasma, freckles, and post-acne marks. It is often combined with other brighteners (like niacinamide or hydroquinone). It is generally milder than hydroquinone and can be a gentler alternative, though it may cause some irritation and works gradually over weeks.

The science

Kojic acid is a fungal-derived metabolite that chelates copper at the active site of tyrosinase, inhibiting melanin synthesis; it also has antioxidant and antimicrobial properties. Clinical studies show 1-2% formulations improve hyperpigmentary disorders (melasma, lentigines, post-inflammatory hyperpigmentation), with efficacy enhanced when combined with agents such as hydroquinone or glycolic acid. Cosmetic-ingredient reviews consider it safe at concentrations up to about 1-2%.

References

• Saeedi M et al., biological activities and safety of kojic acid (review), J Cosmet Dermatol 2022
• Phasha V et al., review on the use of kojic acid, Cosmetics 2022