Metronidazole
"For the last few years I have had recurrences, sometimes as often as once a week of vomiting and diarrhea.  It seemed to be traced to exhaustion and fatty foods.  In the meantime, my wife contacted C. Difficile in the hospital.  Along the way, I may have contracted C.Diffcile too.  In any event, my doctor prescribe Flagyl, which I took four times a day for 10 days.  This cleared everything up but the problem kept occurring.  For the last 45 days I have been taking 2, 250 mg. capsules once a day.  Recently I have cut down to one.  Although I have had occasional diarrhea, there has been no vomiting or nausea.  "