Levofloxacin and Warfarin—we do have concerns regarding an increased bleeding time or watching that INR number they have to watch if a person is on Coumadin, because one of the sister components, Ciprofloxacin, is been known to increase the bleeding time in patients on Coumadin. You don’t want to have the risk of a bleed. So if a person starts to bruise easier, or have nose bleeds, or any other signs of bleeding, the should contact a doctor.