Metronidazole is an antibiotic and antiprotozoal medicine sold under the trade names Flagyl, Metrozine, Gramex and others. It's used to treat pelvic inflammatory disease, endocarditis, and bacterial vaginosis, either alone or in combination with other antibiotics. Dracunculiasis, giardiasis, trichomoniasis, and amebiasis are also treated with it.