Science
Mechanism of Action
This ingredient functions as a hair dyeing agent. There is no information available regarding its mechanism of action on the skin for skincare purposes.
Research
Clinical Evidence
Insufficient-data confidenceN/A
Transparency
Dusting Analysis
The Formula
Formulation
Stability
No specific data regarding the optimal pH range or stability for this exact ingredient has been identified. For chemically related substances, stability data in test solutions and marketed products was noted as not submitted.
Safety
Safety Profile
The Scientific Committee on Consumer Safety (SCCS) considers Hydroxypropyl p-phenylenediamine and its dihydrochloride salt safe when used in oxidative hair colouring products up to a maximum on-head concentration of 2%. However, animal data indicates it is a moderate skin sensitiser, and the potential for mild to moderate eye irritation cannot be excluded. The FDA classifies it as a 'coal tar hair dye,' requiring specific caution statements and patch test instructions. It is explicitly prohibited for use in dyeing eyelashes or eyebrows. An in-vitro EpiskinSM skin irritation test found a 2% concentration in water to be potentially non-irritating.
Your Skin
Skin Compatibility
Our Assessment
Verdict
Due to its primary function as a hair dye, the absence of established skincare benefits, and documented moderate skin sensitization potential, Hydroxypropyl-p-phenylenediamine HCl is not recommended for precision skincare formulations.
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References
Sources