Metronidazole or Flagyl falls under the class of medicines called Antibiotics. Antibiotics are usually used to treat bacterial infections caused by certain bacteria. Metronidazole is intended for the medication of vaginal, intestinal, and abdominal infections. It works by penetrating the cells of the bacteria and it interferes with the bacteria DNA causing it to die. It also prevents in the formation of the bacteria. Doctors usually suggest this medication for these kinds of bacterial infections.