Moderate Active Ingredient NOAEL Data SCCS/CIR Reviewed Dermal Penetration

Kojic Acid

INCI: KOJIC ACID

CAS Number
501-30-4
Function
Tyrosinase inhibitor; chelates copper at the enzyme's active site blocking both monophenolase and diphenolase activity; clinically used at 1–2.5% for melasma and senile pigmentation
Safety Rating
MODERATE

Regulatory Status

🇪🇺 EU Status restricted
EU Max Conc. 1%
🇺🇸 US Status permitted
US Notes No specific FDA concentration restriction for cosmetic brightening use. Typically used at 1–2.5% in OTC brightening products. Not classified as a drug at cosmetic concentrations. Not GRAS-listed for OTC skin bleaching.

For full compliance data across 55 jurisdictions, use the Substance Compliance tool.

Safety Data

Margin of Safety (MoS)
adequate
Dermal Absorption
low
Sensitization
moderate

Calculate MoS for your specific formulation with the MoS Calculator.

Toxicological Studies

10 study endpoints found for Kojic Acid. NOAEL (No Observed Adverse Effect Level) values are used to calculate the Margin of Safety per SCCS methodology.

Endpoint Value Route Species Study Type Source
NOAEL =227 mg/kg/day oral rat (male) chronic CIR
LOAEL 5.84999990463 mg/kg bw/day oral rat Short Term Toxicity COSMOS_DB
NOAEL =6 mg/kg/day oral rat (male) repeat-dose SCCS
NOAELadj =2 mg/kg/day oral rat (male) repeat-dose SCCS
NOAEL =150 mg/kg/day oral rat subchronic SCCS
NOAEL 23.8 mg/kg bw/day oral - - SCCS_PDF_extraction
NOAEL 5.85 mg/kg bw/day oral - - SCCS_PDF_extraction
NOAEL 6 mg/kg bw/day - - - SCCS_PDF_extraction
NOAEL 62.5 mg/kg bw/day - - - SCCS_PDF_extraction
NOAEL 6 mg/kg bw/day oral - reproductive SCCS_PDF_extraction

Safety Opinions

Official safety assessments from the Scientific Committee on Consumer Safety (SCCS) and Cosmetic Ingredient Review (CIR).

sccs SCCS/1637/21 16 March 2022
Verdict: safe
NOAEL: 23.8 mg/kg bw/day (not specified)
Max Concentration: 1% in general

al endocrine disrupting properties of Kojic acid, the SCCS is of the opinion that Kojic acid is safe when used as a skin lightening agent in cosmetic products at concentrations of up to 1%. 2. Alternatively, what is according to the SCCS the maximum concentration considered safe for use of Ko

sccs SCCS/1637/21 16 March 2022
Verdict: safe
NOAEL: 23.8 mg/kg bw/day (not specified)
Max Concentration: 1% in leave-on

al endocrine disrupting properties of Kojic acid, the SCCS is of the opinion that Kojic acid is safe when used as a skin lightening agent in cosmetic products at concentrations of up to 1%. 2. Alternatively, what is according to the SCCS the maximum concentration considered safe for use of Ko

sccs SCCS/1637/21 16 March 2022
Verdict: safe
NOAEL: 5.85 mg/kg bw/day (not specified)
Max Concentration: 1% in general

al endocrine disrupting properties of Kojic acid, the SCCS is of the opinion that Kojic acid is safe when used as a skin lightening agent in cosmetic products at concentrations of up to 1%. 2. Alternatively, what is according to the SCCS the maximum concentration considered safe for use of Ko

sccs SCCS/1637/21 16 March 2022
Verdict: safe
NOAEL: 5.85 mg/kg bw/day (not specified)
Max Concentration: 1% in leave-on

al endocrine disrupting properties of Kojic acid, the SCCS is of the opinion that Kojic acid is safe when used as a skin lightening agent in cosmetic products at concentrations of up to 1%. 2. Alternatively, what is according to the SCCS the maximum concentration considered safe for use of Ko

sccs SCCS/1637/21 16 March 2022
Verdict: safe
NOAEL: 6 mg/kg bw/day (oral)
Max Concentration: 1% in general

al endocrine disrupting properties of Kojic acid, the SCCS is of the opinion that Kojic acid is safe when used as a skin lightening agent in cosmetic products at concentrations of up to 1%. 2. Alternatively, what is according to the SCCS the maximum concentration considered safe for use of Ko

SCCS NOAEL Values

NOAEL/LOAEL values cited in official SCCS opinions for Kojic Acid.

NOAEL LOAEL Route Species Study DA% (SCCS) Opinion
6 mg/kg/day 23.8 mg/kg/day Oral Rat (male) Repeated dose (28-day) (28 days (dietary)) 100 SCCS/1637/21 (2022)
15.5 mg/kg/day - Oral Rat (male) Subacute/repeated dose (20-week feeding) (20 weeks (dietary)) 100 SCCS/1637/21 (2022)
100 mg/kg/day - Dermal Rat (Wistar) Repeated dose (28-day) (28 days) N/A SCCS/1098/14 (2014)
- - Oral Rat/Mouse Developmental toxicity (Gestational period) 100 SCCS/1098/14 (2014)

Dermal Penetration Profile

Skin absorption and penetration characteristics of Kojic Acid, relevant to systemic exposure and MoS calculations.

Absorption %
10-18%
Penetration Level
epidermis
Penetration Depth
epidermis
Molecular Weight
142.1 Da
Log P
-0.75
Systemic Absorption
minimal
Topical Bioavailability
6-14%
Safety Margin Factor
moderate
Vehicle Dependent
Yes — absorption varies by formulation

Source: J Cosmet Dermatol 2011

Expert Verdict

Clinically effective copper-chelating tyrosinase inhibitor with decades of use for melasma and senile pigmentation at 1–2.5%. EU-restricted to 1% in face and hand products under Regulation 2024/996 (placement deadline 1 November 2025; withdrawal deadline 1 May 2027). Japan quasi-drug since 1988; suspended 2003 over rodent liver tumour data; reinstated 2005 after transdermal exposure confirmed negligible at 1% (peak plasma 1.54 ng/mL). Two persistent clinical challenges: aqueous oxidation instability requiring pH optimization, antioxidant co-formulants, or anhydrous vehicles; and contact sensitization in approximately 1–2% of users—a meaningful rate for leave-on products. Kojic acid dipalmitate ester addresses both liabilities at the cost of slower bioactivation. Effective within constraints but requires careful concentration and formulation engineering.

⚠️
Concern Level: Moderate

Regulatory Flags

tyrosinase-inhibitor brightening eu-restricted eu-regulation-2024-996 annex-iii-1pct-face-hand sensitization-risk-1-2pct oxidation-instability copper-chelator melasma hyperpigmentation quasi-drug-japan-1988 japan-suspended-2003-reinstated-2005 aak-combination-evidence endocrine_disruptor

Frequently Asked Questions

Is Kojic Acid safe in cosmetics?

Clinically effective copper-chelating tyrosinase inhibitor with decades of use for melasma and senile pigmentation at 1–2.5%. EU-restricted to 1% in face and hand products under Regulation 2024/996 (placement deadline 1 November 2025; withdrawal deadline 1 May 2027). Japan quasi-drug since 1988; suspended 2003 over rodent liver tumour data; reinstated 2005 after transdermal exposure confirmed negligible at 1% (peak plasma 1.54 ng/mL). Two persistent clinical challenges: aqueous oxidation instability requiring pH optimization, antioxidant co-formulants, or anhydrous vehicles; and contact sensitization in approximately 1–2% of users—a meaningful rate for leave-on products. Kojic acid dipalmitate ester addresses both liabilities at the cost of slower bioactivation. Effective within constraints but requires careful concentration and formulation engineering. The EU classifies Kojic Acid as "restricted". Safety rating: MODERATE. 10 toxicological study endpoint(s) are available in our database. This ingredient has been reviewed by sccs.

Is Kojic Acid allowed in the EU?

Kojic Acid EU regulatory status: restricted. Maximum allowed concentration: 1%. This is based on EU Regulation 1223/2009 and its amendments.

What does Kojic Acid do in cosmetics?

Kojic Acid functions as: Tyrosinase inhibitor; chelates copper at the enzyme's active site blocking both monophenolase and diphenolase activity; clinically used at 1–2.5% for melasma and senile pigmentation. It is classified as a Active Ingredient in our database. CAS number: 501-30-4.

What is the Margin of Safety for Kojic Acid?

adequate The Margin of Safety (MoS) is calculated using SCCS methodology. A MoS above 100 is generally considered safe. Use the MoS Calculator tool to calculate MoS for your specific formulation and product category.

What is the NOAEL for Kojic Acid?

The NOAEL (No Observed Adverse Effect Level) for Kojic Acid is =227 mg/kg/day based on a chronic study via oral route in rat (male). A total of 10 study endpoints are available. Source: CIR.

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