This study aimed to evaluate in vitro the pharmacological stability of a herbal mouthwash based on Libidibia ferrea extract after aging, establishing its organoleptic and microbiological characteristics. It is a 7.5% hydroalcoholic extract from Libidibia ferrea pods, using the reflux decoction technique, and spray dried. The stability, pH, sedimentation, density, and antimicrobial activity tests of the mouthwash were performed with the solutions stored after 24 months. Contaminant control was carried out by determining the total number of microorganisms and researching Salmonella sp., Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. The formulation's antimicrobial activity against microorganisms present in the dental biofilm was analyzed: Streptococcus mutans, Streptococcus salivarius, Lactobacillus casei, and Candida albicans., The data were analyzed using the Tukey test to assess pH and density, and the other results were described using descriptive statistics., The color observed in the organoleptic characters, was “Ceramics”, with a fluid/serous consistency, shiny appearance, and a strong minty, woody odor. In the sedimentation phase, the separation was observed, and the pH and density analyzes showed a mean value of 5.46 and 1.029 g/cm3, respectively. The contaminant assessment test was negative for all microorganisms surveyed, within 24 months. The mouthwash showed bactericidal/fungicidal activity against all the microorganisms tested at all concentrations for S. mutans and C. albicans. At concentrations 0.5 mg/ml for S. salivarius and 0.6 mg/ml for L casei. It was concluded that after 24 months, the formulation of the mouthwash based on L. ferrea, its initial characteristics remained stable except for the homogeneity and pH of the solution.