Science
Mechanism of Action
This ingredient operates as a disinfectant by competitively disrupting hydrogen ion interactions within microbial enzyme systems, leading to their inactivation. Its primary targets include Gram-positive bacteria such as *Staphylococcus aureus*, *Pseudomonas aeruginosa*, *Candida albicans*, and *Trichosporon* species. Although its precise mechanism is not fully elucidated, its activity against *S. aureus* is notably enhanced in environments with higher pH.
Research
Clinical Evidence
High confidence0.1%
Key findings
- 01 Demonstrated marked antifungal activity against *Candida* and *Trichosporon* species under both aerobic and anaerobic conditions.
- 02 Suggested as the optimal applied strength for solutions, aiming to mitigate the risk of skin rashes observed at concentrations exceeding 0.5%.
- 03 Significantly reduced *Staphylococcus aureus* density in skin and improved clinical severity of eczema in patients with impetiginized eczema within 4 days.
- 04 Showed anti-irritative and antimicrobial effects, evidenced by significant reductions in stratum corneum water content, subpapillary blood flow, and barrier damage in an SLS-induced irritation model.
- 05 Exhibited rapid bactericidal effect (within 30 seconds) against various clinical isolates, including drug-resistant bacteria like MRSA, and is used clinically for mucosal infections and burns.
Transparency
Dusting Analysis
Methylrosanilinium Chloride is largely avoided in cosmetic formulations. The Cosmetic Ingredient Review (CIR) Expert Panel found insufficient safety data, and manufacturers do not report its use in the US FDA Voluntary Cosmetic Registration Program. Animal studies indicate dose-related carcinogenicity with long-term oral intake, and it is classified as 'Suspected of causing cancer' (H351). Additionally, it causes skin rashes at concentrations above 0.5%, carries a high irritancy potential, can cause allergic reactions, ulcerations, necrotic skin reactions, and persistent staining, making it highly unsuitable for cosmetic applications.
The Formula
Formulation
Stability
Optimal stability is observed in an acidic pH range of 2.5-3.5, though activity against *S. aureus* increases with higher pH. It is sensitive to light. Diluted solutions have a maximum shelf life of one week, requiring storage in dry, dark conditions at 0-4°C (short-term) or -20°C (long-term).
Conflicts
- strong oxidizing agents
- strong acids
Safety
Safety Profile
The CIR Expert Panel assessed its safety with insufficient data. It is not reported for use in US cosmetics. Animal studies indicate dose-related carcinogenicity with long-term oral intake, causing liver cancer, adenoma, and sarcoma, and it is classified as 'Suspected of causing cancer' (H351). While systemic absorption is considered low with topical use, long-term, large-dose, or large-area application should be avoided. The FDA discontinued its use as a drug for vaginal applications, though it is a Class I medical device for dye and stain purposes. It presents a high risk for irritation, ulcerations, allergic reactions, and persistent skin staining. Necrotic skin reactions can occur at high concentrations, particularly in skin folds, and oral ulceration has been reported in neonates with topical treatment. The SCCS has not published an opinion. INCIDecoder rates its irritancy as high.
Your Skin
Skin Compatibility
Our Assessment
Verdict
Due to significant safety concerns, including potential carcinogenicity in animal studies, high irritancy, risk of allergic reactions, and persistent skin staining, Methylrosanilinium Chloride is not recommended for use in cosmetic formulations.
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