To reduce the development of drug-resistant bacteria and maintain the effectiveness of Flagyl ® and other antibacterial drugs, Flagyl ® should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria. Flagyl (metronidazole) is an antibiotic prescribed to treat various parasitic and bacterial infections (Giardia, C. diff, H. pylori). Common side effects are headaches, nausea, and metallic taste in the mouth. Pregnancy and breastfeeding safety information are provided. Flagyl is an antibiotic used to treat various infections, including certain sexually transmitted infections. This eMedTV page explains how Flagyl works and offers more details on the drug's specific uses, dosing guidelines, and potential side effects. Metronidazole is an antibiotic. It's used to treat skin infections, rosacea and mouth infections (including infected gums and dental abscesses). It's used in the treatment of conditions such as bacterial vaginosis and pelvic inflammatory disease. Flagyl for dogs hasn’t been approved but it is used by some veterinary specialists. Flagyl is also known as metronidazole is an antibiotic that can be used in various canine infections. Flaygl is the common trade name of a drug called Metronidazole. It is suggested for several conditions but is often used to treat c.difficile. Flagyl (metronidazole) is an antibiotic that fights bacteria. Flagyl is used to treat bacterial infections of the vagina, stomach, liver, skin, joints, brain, and respiratory tract. Uses. Protozoal infections: extra-intestinal amebiasis (including amoebic liver abscess), intestinal amoebiasis (amoebic dysentery), trichomoniasis, balantidiasis. Metronidazole is the generic form of the brand name drug Flagyl, which is used to treat bacterial infections of the skin, vagina, stomach, joints, or respiratory tract. To reduce the development of drugresistant bacteria and maintain the effectiveness of FLAGYL® and other antibacterial drugs, FLAGYL® should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.