Metronidazole is not a sulfa drug. It is an antibiotic used to treat bacterial infections of the vagina, stomach, skin, joints and respiratory tract. Drugs.com states that it is not used to treat vaginal yeast infections. Metronidazole is formulated as a prescription oral tablet or an intravenous drug.
Metronidazole is the generic name for a drug that is also marketed under several brand names that include Flagyl, Flagyl 375, Protostat and Metryl. Women in the first trimester of pregnancy should not take this medication, according to Drugs.com. Since Metronidazole can also pass into breast milk, mothers taking this drug should talk to a doctor before nursing a baby.