Good Active Ingredient NOAEL Data SCCS/CIR Reviewed

Genistein

INCI: GENISTEIN

CAS Number
446-72-0
Function
5-alpha-reductase inhibitor; phytoestrogen; ER modulator; anti-androgenic; antioxidant; hair-growth active
Safety Rating
GOOD

Regulatory Status

🇪🇺 EU Status permitted
🇺🇸 US Status permitted
US Notes Permitted cosmetic active. No OTC drug monograph. Phytoestrogenic mechanism means claim language requires care to avoid drug classification.

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Safety Data

Margin of Safety (MoS)
adequate
Dermal Absorption
moderate
Sensitization
none

Calculate MoS for your specific formulation with the MoS Calculator.

Toxicological Studies

2 study endpoints found for Genistein. 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 =0.3 mg/kg/day oral rat (Sprague-Dawley) reproductive SCCS
NOAEL >50 mg/kg/day oral rat subchronic SCCS

Safety Opinions

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

sccs SCCS/1641/2022 16 September 2022
Verdict: safe
NOAEL: 4 mg/kg bw/day (subcutaneous)
Max Concentration: 0.007% in general

e and justified than the data from oral studies. The SCCS considers that the calculation of margin of safety (MoS) for daidzein based on the data from subcutaneous route would provide a more reliable indicator of SCCS/1641/22 Final version Corrigendum October 2022 Opinion on genistein and daidzein

sccs SCCS/1641/2022 16 September 2022
Verdict: safe
NOAEL: 4 mg/kg bw/day (subcutaneous)
Max Concentration: 0.02% in general

e and justified than the data from oral studies. The SCCS considers that the calculation of margin of safety (MoS) for daidzein based on the data from subcutaneous route would provide a more reliable indicator of SCCS/1641/22 Final version Corrigendum October 2022 Opinion on genistein and daidzein

sccs SCCS/1641/2022 16 September 2022
Verdict: safe
NOAEL: 35 mg/kg (not specified)
Max Concentration: 0.007% in general

e and justified than the data from oral studies. The SCCS considers that the calculation of margin of safety (MoS) for daidzein based on the data from subcutaneous route would provide a more reliable indicator of SCCS/1641/22 Final version Corrigendum October 2022 Opinion on genistein and daidzein

sccs SCCS/1641/2022 16 September 2022
Verdict: safe
NOAEL: 35 mg/kg (not specified)
Max Concentration: 0.02% in general

e and justified than the data from oral studies. The SCCS considers that the calculation of margin of safety (MoS) for daidzein based on the data from subcutaneous route would provide a more reliable indicator of SCCS/1641/22 Final version Corrigendum October 2022 Opinion on genistein and daidzein

SCCS NOAEL Values

NOAEL/LOAEL values cited in official SCCS opinions for Genistein.

NOAEL LOAEL Route Species Study DA% (SCCS) Opinion
50 mg/kg/day 150 mg/kg/day Oral Rat (Sprague-Dawley) Developmental/reproductive (Gestational/neonatal period) 20 SCCS/1641/22 (2022)

Expert Verdict

Genistein, the principal isoflavone from soy, operates through dual mechanisms in hair loss: 5α-reductase inhibition (reducing DHT) and estrogen receptor modulation (phytoestrogenic effect providing follicle-protective benefits). Particularly relevant to postmenopausal FPHL where estrogen decline activates DHT-mediated follicle miniaturization. Evidence is primarily in vitro and limited human studies; FPHL-specific large RCTs are lacking. SCCS calculated adequate margin of safety (≥100) at 0.007%. Phytoestrogenic activity requires careful claim positioning in EU cosmetics to avoid medicinal product classification. GOOD safety profile at cosmetic use levels.

⚠️
Concern Level: Low

Regulatory Flags

hair-growth-active 5ar-inhibitor phytoestrogen anti-androgenic soy-derived claim-sensitive cosmetic-classified endocrine_disruptor

Frequently Asked Questions

Is Genistein safe in cosmetics?

Genistein, the principal isoflavone from soy, operates through dual mechanisms in hair loss: 5α-reductase inhibition (reducing DHT) and estrogen receptor modulation (phytoestrogenic effect providing follicle-protective benefits). Particularly relevant to postmenopausal FPHL where estrogen decline activates DHT-mediated follicle miniaturization. Evidence is primarily in vitro and limited human studies; FPHL-specific large RCTs are lacking. SCCS calculated adequate margin of safety (≥100) at 0.007%. Phytoestrogenic activity requires careful claim positioning in EU cosmetics to avoid medicinal product classification. GOOD safety profile at cosmetic use levels. The EU classifies Genistein as "permitted". Safety rating: GOOD. 2 toxicological study endpoint(s) are available in our database. This ingredient has been reviewed by sccs.

Is Genistein allowed in the EU?

Genistein EU regulatory status: permitted. This is based on EU Regulation 1223/2009 and its amendments.

What does Genistein do in cosmetics?

Genistein functions as: 5-alpha-reductase inhibitor; phytoestrogen; ER modulator; anti-androgenic; antioxidant; hair-growth active. It is classified as a Active Ingredient in our database. CAS number: 446-72-0.

What is the Margin of Safety for Genistein?

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 Genistein?

The NOAEL (No Observed Adverse Effect Level) for Genistein is =0.3 mg/kg/day based on a reproductive study via oral route in rat (Sprague-Dawley). A total of 2 study endpoints are available. Source: SCCS.

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