Science
Mechanism of Action
As a direct dye, Acid Red 18 adheres to the hair shaft surface through electrostatic interactions without deep penetration or chemical reaction. Its mechanism is solely chromatic, providing visual coloring rather than active biological effects.
Research
Clinical Evidence
High confidenceN/A
Key findings
- 01 SCCS evaluated Acid Red 18 as safe for use in semi-permanent hair dyes at 0.5% and in oxidative hair dye formulations up to 1.5%.
- 02 Historical animal studies showed no carcinogenic effects in mice at dietary levels of 0.01-1.25%, with mild kidney and liver effects only at maximum doses (1750 mg/kg/day).
Transparency
Dusting Analysis
The Formula
Formulation
Stability
This ingredient is hygroscopic and stable in acidic conditions, but it undergoes browning in strong alkaline solutions. It also demonstrates poor resistance to reducing agents and bacteria.
Conflicts
- reducing agents
- strong alkaline solutions
- oxidizing agents (in non-oxidative systems)
Safety
Safety Profile
The SCCS (EU) deems Acid Red 18 safe up to 1.5% in oxidative and 0.5% in non-oxidative hair dyes. Animal data suggests no carcinogenic potential, with mild organ effects occurring only at very high dietary concentrations.
Your Skin
Skin Compatibility
Our Assessment
Verdict
While generally safe for coloring within established limits, its high comedogenicity renders it unsuitable for precision skincare, particularly in leave-on formulations.
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References
Sources