Metronidazole is an antibiotic. It is particularly effective against anaerobic bacteria and protozoa. It is most commonly used against Clostridium difficile, rosacea, bacterial vaginosis, heliobacter pylori, endometriosis and endocarditis.
Like most other antibiotics, its primary side effects are nausea, diarrhea and allergic reactions. It also has a medicine interaction with alcohol.