Cosmetics · Quasi-drug actives
Kojic Acid
コウジ酸 (Kōji-san)
Also known as: 5-Hydroxy-2-(hydroxymethyl)-4H-pyran-4-one
At a glance
| Category | Cosmetics |
|---|---|
| INCI name | Kojic Acid |
| Japanese labeling name | コウジ酸 |
| Common Japanese notations | コウジ酸, 麹酸 |
| CAS number | 501-30-4 |
| Origin | Fermented (originally identified as a metabolite of Aspergillus oryzae) |
| Typical functions | Quasi-drug whitening active |
| Regulatory status in Japan | Approved as a quasi-drug (医薬部外品) whitening active by MHLW within defined concentration ranges. |
Kojic acid was first identified by Japanese researchers as a metabolite of Aspergillus oryzae — the same koji mold central to sake, miso, and soy sauce production. Its name comes directly from this fermentation origin (kōji + -san meaning acid). It is used as a quasi-drug whitening active in Japan and as a cosmetic ingredient internationally.
Classification
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Product applications
Functions
Regulatory tags
Used in (typical product categories)
Finished-product categories that commonly include this ingredient in Japanese-market formulations.
- Medicated whitening serums and lotions
- Spot-care products
- Soap bars (whitening positioning)
What it is
Kojic acid is a pyranone produced by various Aspergillus and Penicillium species during fermentation. Its discovery as a fermentation metabolite of Aspergillus oryzae gave the compound both its name and a particularly Japanese association.
It functions in melanin synthesis as a tyrosinase inhibitor.
Typical uses in Japanese products
In Japanese quasi-drug whitening products, kojic acid is one of the established approved active ingredients. Internationally, kojic acid is used in cosmetic preparations across many markets, with concentration limits varying by jurisdiction.
Regulatory classification in Japan
Approved as a quasi-drug whitening active ingredient by MHLW within defined concentration ranges.
Regulatory classification in other markets
| EU | Listed in CosIng under Kojic Acid. EU SCCS opinion permits cosmetic use up to 1.0 percent in face and hand products. |
|---|---|
| USA | INCI recognized. Used in cosmetic products. |
| China | Permitted per IECIC listings; verify concentration ranges. |
| Korea | Permitted under KFDA / MFDS. |
Example products
Example finished products will be added after each product's current full ingredient list has been verified.
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Related ingredients
References
- Japan PMDA — quasi-drug active ingredient approval registry
- EU SCCS opinion on kojic acid
Last updated: 2026-04-22. Ingredient entries are reviewed at least annually against current regulatory listings.