###Human: Had an appendectomy last week, they started me on antibiotics, Flagyl, through an IV. Would this affect my birth control? ###Assistant: Hi. Flagyl (Metronidazole) as such has no effect on birth control. You need not take any extra precautions for the sake of Flagyl itself. But, if you were on pills earlier and had to discontinue due to surgery, then, of course, you need other protection. To know the methods of birth control consult an obstetrician and gynaecologist online -->