all antibiotics kill off good bacteria unfortunately, thus those dreaded yeast infections, this also drives my wife nuts every time, doesn't matter what type, its the fact its an antibiotic, sorry for the discomfort Erin matter of fact last stay in hospital they had me on so much antibiotics they were also giving me good bacteria separately, i don't recall what could of happened to me if they didn't give me good bacteria but i seem to recall it wasn't a pretty picture