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Moumoujus

6-METHOXY-2,3-PYRIDINEDIAMINE HCL.

Avoid CAS 94166-62-8 / HAIR DYEING

A synthetic aromatic amine compound primarily developed as a hair dye precursor that undergoes oxidative coupling reactions to form colored pigments. While approved for hair coloring applications at concentrations up to 1.0%, this ingredient has limited relevance in facial skincare due to its moderate sensitization potential and lack of established skin benefits.

Summary

hair dyeing

Science

Mechanism of Action

Functions as a chemical precursor that reacts with oxidizing agents and developers to create larger chromophore molecules for hair pigmentation. On skin, it may trigger Type IV hypersensitivity reactions through protein binding, but lacks any documented beneficial biological activity for skincare applications.

Research

Clinical Evidence

Medium confidence
Effective range ≤1%
Optimal

N/A

Key findings

  1. 01 SCCP safety evaluation at 1.0% concentration for hair dye use (2008)
  2. 02 LLNA study determining EC3 value of 5.6% for sensitization threshold
  3. 03 Human patch testing at 10.0% showing irritation in 20% of subjects

Transparency

Dusting Analysis

Not commonly dusted

This ingredient is not typically used in skincare formulations, making dusting analysis irrelevant for precision skincare evaluation.

The Formula

Formulation

Solubility
Water
Optimal pH 1.5 – 3.5
0 7 14

Stability

Exhibits optimal stability in highly acidic aqueous environments (pH 1.8-3.0) with rapid degradation in organic solvents and requires protection from light and moisture exposure.

Conflicts

  • Strong oxidizing agents
  • Nitrosating compounds (nitrosamine formation risk)
  • Alkaline pH environments (causes precipitation and instability)

Safety

Safety Profile

CIR Status
Not reviewed
Max tested
1%
Sensitization risk Moderate

EU Cosmetic Regulation limits use to 1.0% in finished products. Classified as moderate skin sensitizer with documented potential for contact dermatitis and irritation responses.

Your Skin

Skin Compatibility

No Normal
No Dry
No Oily
No Sensitive
Irritancy Moderate
Comedogenicity Unknown

Our Assessment

Verdict

Avoid

Inappropriate for precision skincare due to moderate sensitization risk, lack of skin benefits, and primary function as a hair dye precursor rather than a skincare active.

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