Good Active Ingredient NOAEL Data SCCS/CIR Reviewed

Soy Isoflavones

INCI: SOY ISOFLAVONES

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

Regulatory Status

๐Ÿ‡ช๐Ÿ‡บ EU Status permitted
๐Ÿ‡บ๐Ÿ‡ธ US Status permitted
US Notes Permitted cosmetic active (genistein, daidzein, equol blend). Phytoestrogenic mechanism requires careful claim framing to avoid OTC drug classification.

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

Safety Data

Margin of Safety (MoS)
not established
Dermal Absorption
moderate
Sensitization
low

Calculate MoS for your specific formulation with the MoS Calculator.

Toxicological Studies

2 study endpoints found for Soy Isoflavones. 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

Expert Verdict

Soy isoflavones (genistein, daidzein, equol) inhibit 5ฮฑ-reductase and modulate estrogen receptors, relevant to postmenopausal hair loss; evidence is primarily in vitro and observational. Cosmetic classification is maintained at standard concentrations, but claims referencing hormonal or DHT mechanisms require careful framing under EU cosmetics law. Safety profile is good at cosmetic use levels.

โš ๏ธ
Concern Level: Low

Regulatory Flags

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

Frequently Asked Questions

Is Soy Isoflavones safe in cosmetics?

Soy isoflavones (genistein, daidzein, equol) inhibit 5ฮฑ-reductase and modulate estrogen receptors, relevant to postmenopausal hair loss; evidence is primarily in vitro and observational. Cosmetic classification is maintained at standard concentrations, but claims referencing hormonal or DHT mechanisms require careful framing under EU cosmetics law. Safety profile is good at cosmetic use levels. The EU classifies Soy Isoflavones as "permitted". Safety rating: GOOD. 2 toxicological study endpoint(s) are available in our database. This ingredient has been reviewed by sccs.

Is Soy Isoflavones allowed in the EU?

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

What does Soy Isoflavones do in cosmetics?

Soy Isoflavones functions as: 5-alpha-reductase inhibitor; phytoestrogen blend; 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 Soy Isoflavones?

not established 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 Soy Isoflavones?

The NOAEL (No Observed Adverse Effect Level) for Soy Isoflavones 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.

๐Ÿ“ฑ

Is Soy Isoflavones in Your Products?

Scan any product label with Piro โ€” our free ingredient scanner. Point your camera at the ingredients list and get instant safety scores for every ingredient.

Try Piro Free โ†’

Analyze Your Full Ingredient List

Paste any INCI list into the Decoder for instant safety analysis, or calculate the Margin of Safety for Soy Isoflavones in your formulation.