<![CDATA[Poor oral hygiene promotes the shift of commensal microorganisms into opportunistic pathogens, causing oral diseases. Natural phenolic-rich products like propolis and roselle (Hibiscus sabdariffa) offer promising antimicrobial properties for oral care. This study aimed to evaluate the combined antimicrobial activity of ethanolic extract of propolis (EEP) and aqueous extract of roselle (AER) against Staphylococcus aureus, Streptococcus mutans, and Candida albicans, and to formulate an effective natural mouthwash. MIC and MBC/MFC values were determined for both extracts. Combined interactions were evaluated using checkerboard assays (FICI). A mouthwash containing 2% EEP and 1% AER was formulated and assessed for physical properties and time-kill kinetics. EEP showed MIC values against S. aureus, S. mutans, and C. albicans of 1,280, 640, and > 20,480 μg/mL, respectively, whereas AER yielded 320, 1,280, and 10,240 μg/mL. EEP MBC values were 1,280 and 2,560 μg/mL for bacterial strains, while AER MBC/MFC values were 1,280, 10,240, and 10,240 μg/mL. Checkerboard assays indicated additive interactions against S. aureus (FICI = 2) and S. mutans (FICI = 3). The formulated mouthwash (2% EEP, 1% AER) was homogeneous, transparent light-brown, menthol-scented, with pH 5.44 ± 0.03 and viscosity 1.36 mPa. Undiluted, it completely eradicated all microbes within 2–10 minutes. The EEP–AER combination exhibits strong antimicrobial activity and holds great potential as a natural mouthwash for oral health management.]]>
