On GuardⓇ! Antimicrobial activity of a proprietary essential oil blend against skin microbes


  • Christa Powers Mount Royal University


There is ample research highlighting the antimicrobial activity of the essential oils (EOs) like cinnamon, clove, orange, rosemary, and eucalyptus found in dōTERRA©’s proprietary On Guard blend. This suggests that the essential oil blend (EOB) may have its own antimicrobial properties; however, currently there is no published literature to confirm this. The purpose of this study was to investigate the antimicrobial activity of dōTERRA© On Guard products against Staphylococcus epidermidis, Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa. To address this, the EOB was tested using a Kirby-Bauer disc diffusion assay in order to determine the antimicrobial activity of the EOB against skin microbes. Based on previously published research, it was proposed that the On Guard EOB would have antimicrobial activity towards some or all of the selected microbes since its EO components have been shown to have antimicrobial properties. It was found that the EOB showed statistically significant antimicrobial activity against all four species of skin bacteria. Interestingly, the cinnamon EO showed the highest antimicrobial activity, and even outperformed the chloramphenicol positive control in some trials. The EOB also seemed to more selectively inhibit S. aureus over S. epidermidis. These findings strongly suggest that the On Guard EOB does have antimicrobial activity but further research is needed in order to confirm the statistical significance of the selectivity of the EOB, to solidify its potential as a treatment for bacterial skin conditions.


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