Drug	Dosage	Mode of administration	Efficacy	Side effects	Price*	Advantages and disadvantages
Metronidazole (Flagyl)	500 mg orally every six to eight hours for 10 to 14 days Alternatives: 250 mg every six hours for 10 to 14 days and 500 mg IV every eight hours for 10 to 14 days	Oral and IV	> 90%	Nausea, vomiting Metallic taste Potentiation of warfarin (Coumadin) Disulfiram-like reaction	$256 (36 to 40): 500 mg orally every six hours for 14 days $678 (103 to 644): 500 mg IV every eight hours for 14 days	Effective by IV administration Less expensive than vancomycin More side effects than vancomycin
Vancomycin (Vancocin)	125 to 500 mg orally every six hours for 10 to 14 days	Oral only† Nasogastric tube Retention enema	> 90%	Minimal; can include unpleasant taste, mouth irritation, nausea or vomiting; rarely, rash	$1,724: 500 mg orally every six hours for 14 days	Safe for use in pregnant women High cost Use may lead to resistance
Vancomycin retention enemas			Uncertain		Variable