The present invention relates to compositions comprising thioridazine, and derivatives thereof, together with antibacterials. These compositions have been found greatly enhance the activity of many classes of antibacterials, allowing the antibacterials to be administered at significantly lower doses. The thioridazine and the antibacterial act synergistically by pacifying the bacteria to the antibacterials. This synergistic affect lowering the inhibitory or effective concentration of the antimicrobials is most pronounced with the levorotatory isomer of thioridazine compared to the racemic or dextrorotatory isomer.