Purpose: The aims of this study were to analyze whether or not Cololo SP solution developed in Japan could be an alternative or superior to Hexamedine solution.Materials and Methods: Analysis was done by evaluating the bactericidal effects of mouthwash. Several methodologies tested, e.g., mixing bacteria directly into the mouthwash and long-term treatment of bacteria with solution.Results: Bacterial suspension treated twice with 80-fold diluted Cololo SP solution (1 hour of incubation at room temperature [RT] and 4 hours of incubation at RT) was more effective than single-directed inoculation of bacteria mixed with Cololo SP solution.Conclusion: The recommended dosage for Hexamedine solution application is two times for 1 min/d, and application should not be continued for more than 2 weeks. Thus, a new therapy needs to be developed to facilitate its continuous application as a mouthwash. Hexamedine solution is generally harmful if used for even 10 days. Therefore, our data suggest that Cololo SP solution would be a better alternative to Hexamedine solution.