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Moumoujus

O-CYMEN-5-OL.

Valuable CAS 3228-02-2 / 39660-61-2 / ANTIMICROBIAL, DEODORANT, PRESERVATIVE

O-Cymen-5-ol is a phenolic compound valued for its broad-spectrum antimicrobial properties against bacteria, yeasts, and fungi. It functions as an effective preservative, extending product integrity, while also offering direct benefits such as mild exfoliation, anti-inflammatory action, and targeted support for acne-prone skin.

Summary

Antimicrobial Deodorant Preservative Exfoliant Anti-inflammatory Antioxidant Anti-acne

Science

Mechanism of Action

This ingredient acts as a potent antimicrobial, inhibiting the growth of various microorganisms on the skin and within cosmetic formulations. On the skin, it also provides deodorizing effects by combating odor-causing bacteria, exhibits anti-inflammatory properties, and specifically targets *Bacillus acnes*. It supports skin radiance by functioning as a mild exfoliant, promoting the natural shedding of epithelial cells, and offers some antioxidant protection by absorbing specific UV wavelengths.

Research

Clinical Evidence

Medium confidence
Effective range 1.7mM–6.7mM%
Optimal

0.1%

Key findings

  1. 01 In in vitro studies, O-Cymen-5-ol demonstrated Minimum Inhibitory Concentrations (MIC) between 1.7mM and 3.4mM against oral anaerobic species, including *Streptococcus mutans* and *Porphyromonas gingivalis*. Minimum Bactericidal Concentrations (MBC) ranged from 3.4mM to 6.7mM for these species.
  2. 02 A significant synergistic antimicrobial effect was observed at 0.42mM O-Cymen-5-ol when combined with 0.69mM zinc gluconate against oral anaerobic species.

Transparency

Dusting Analysis

Not commonly dusted
Min. effective
0.1%
Red flag below
>0.1%

O-Cymen-5-ol is strictly regulated in cosmetics, with a maximum allowable concentration of 0.1% in both European and CIR guidelines. Usage above this threshold is considered a red flag due to potential safety concerns, including historical animal studies suggesting neurotoxicity, which led to usage restrictions in Japan. The raw material (at >95% concentration) is classified as a skin and serious eye irritant.

The Formula

Formulation

Solubility
Oil
Optimal pH ≤9
0 7 14

Stability

A colorless, odorless crystalline solid, O-Cymen-5-ol is stable to light and suitable for standard emulsification processes up to 80°C. It is prone to reaction with strong oxidizing agents, forming dimers, and should be protected from such interactions. Stability is compromised at pH values above 9.0.

Synergies

  • Enhanced antimicrobial efficacy when combined with zinc gluconate.
  • Bactericidal power can be improved with enhancers like EDTA2Na or by conversion to an anionic system when formulated with macromolecular nonionic surfactants.

Conflicts

  • Oxidizing agents
  • Strong bases
  • pH values above 9.0
  • Macromolecular compounds (e.g., nonionic surfactants, can reduce bactericidal power)
  • Camphor or menthol (vigorous stirring can lead to eutectic crystal mixture and liquefaction)

Safety

Safety Profile

CIR Status
Safe with restrictions
Max tested
0.1%%
Sensitization risk Low

The CIR Expert Panel and European cosmetic regulations deem O-Cymen-5-ol safe for cosmetic use at concentrations not exceeding 0.1%. While generally well-tolerated, rare instances of irritation and redness have been observed, particularly for individuals with sensitive skin, for whom a patch test is advisable. Concerns regarding neurotoxicity in animals from Japanese studies dating back to 1956 have led to usage restrictions in Japan, though further human-specific investigations are indicated. The raw ingredient (>95% pure) is classified as a skin and serious eye irritant.

Your Skin

Skin Compatibility

Yes Normal
No Dry
Yes Oily
No Sensitive
Irritancy Low
Comedogenicity Unknown

Our Assessment

Verdict

Valuable

O-Cymen-5-ol is a valuable ingredient for precision skincare, offering broad antimicrobial protection, anti-acne benefits, and mild exfoliation within its established safe concentration limit of 0.1%.

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