According to WebMD, penicillin is not commonly prescribed to cure bacterial vaginosis. Antibiotics such as clindamycin, metronidazole and tinidazole destroy bacteria that cause bacterial vaginosis.
Certain antibiotics used to treat bacterial vaginosis can be taken by mouth or inserted into the vagina as cream, gel or a suppository. Vaginal medicines are advantageous because they cause fewer systemic side effects than oral medications, according to WebMD. Pregnant women, specifically those at high risk for preterm labor, are advised to avoid vaginal treatment. Bacterial vaginosis frequently comes back after treatment, so sometimes doctors prescribe medication for a longer time period to prevent recurrence.