Kojic Acid
AKA “501-30-4, 5-Hydroxy-2-(hydroxymethyl)-4H-pyran-4-one, 5-Hydroxy-2-(hydroxymethyl)-4-pyrone, 5-hydroxy-2-(hydroxymethyl)pyran-4-one, 4H-PYRAN-4-ONE, 5-HYDROXY-2-(HYDROXYMETHYL)-, 5-Hydroxy-2-hydroxymethyl-4-pyrone, acido kojico, 2-Hydroxymethyl-5-hydroxy-gamma-pyrone, 2-(Hydroxymethyl)-5-hydroxy-4H-pyran-4-one”
Acid
Ingredient Facts
Kojic acid
AKA: 501-30-4, 5-Hydroxy-2-(hydroxymethyl)-4H-pyran-4-one, 5-Hydroxy-2-(hydroxymethyl)-4-pyrone, 5-hydroxy-2-(hydroxymethyl)pyran-4-one, 4H-PYRAN-4-ONE, 5-HYDROXY-2-(HYDROXYMETHYL)-, 5-Hydroxy-2-hydroxymethyl-4-pyrone, Acido kojico, 2-Hydroxymethyl-5-hydroxy-gamma-pyrone, 2-(Hydroxymethyl)-5-hydroxy-4H-pyran-4-one
Acid · Antioxidant · EWG: 7
Synthetic
Antioxidant
Ferment
Acid
Not Clean
5-Hydroxy-2-hydroxymethyl-4-pyrone
Solubility Soluble in ethanol, ethyl ether, acetone, DMSO; slightly soluble in benzene
Formula
C6H6O4
Mol. Weight
142.11
CAS #
501-30-4
Form
Liquid
State
Solid
See origin →
Functions
Antioxidant
Fights free radicals — the unstable molecules from UV, pollution, and stress that break down collagen and cause premature aging.
Evens pigmentation
Brightens uneven skin tone
Traditional Use
Kojic acid was discovered in 1912 as a byproduct of sake (Japanese rice wine) fermentation. It has been used since the 1960s in East Asian skincare, particularly Japan, as a skin-brightening and tyrosinase-inhibiting agent for treating hyperpigmentation.
Skin Types
●all-skin-types
Best For
Hyperpigmentation
Pregnancy & Breastfeeding Safe
Caution
EWG
7
CIR
Insufficient data
Pregnancy
Caution
CIR Safety Findings
Not a Sensitizer
all-shades-safe
Concentration Guide
1.0%
0%1%
Reg. Limit
EU/SCCS limit: 1% in cosmetic products. Opinion: SCCS/1637/21
Regulatory Agencies
Final Report of the Safety Assessment of Kojic Acid as Used in Cosmetics
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Kojic Acid
European Commission
EU Cosmetic Ingredient Database (CosIng)
Kojic Acid
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
Analytical Method for the Identification and Assay of Kojic Acid, Methylparaben, and Propylparaben in Cosmetic Products Using UPLC: Application of ISO
Qadir MA, Ahmed M, Shafiq MI, Ali A, Sadiq A
Journal of AOAC International, 2016
Kojic acid applications in cosmetic and pharmaceutical pr...
Majid Saeedi, Masoumeh Eslamifar, Khadijeh Khezri
Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie, 2019
Kojic acid applications in cosmetic and pharmaceutical pr...
Majid Saeedi, Masoumeh Eslamifar, Khadijeh Khezri
Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie, 2019
Kojic acid applications in cosmetic and pharmaceutical pr...
Majid Saeedi, Masoumeh Eslamifar, Khadijeh Khezri
Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie, 2019
Kojic acid applications in cosmetic and pharmaceutical preparations.
Saeedi M, Eslamifar M, Khezri K
Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie, 2019
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR