Antibiotics for bacterial vaginosis

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Antibiotics for bacterial vaginosis


Generic NameBrand Name
clindamycinDalacin [oral, vaginal]
metronidazoleFlagyl [oral, vaginal]

These antibiotic medicines can be taken by mouth in pill form (orally) or inserted into the vagina in cream or suppository form (ovules). Vaginal creams are used with an applicator that inserts the correct amount of medicine.

How It Works

Metronidazole and clindamycin are antibiotics that destroy some of the bacteria that cause symptoms of bacterial vaginosis.

Why It Is Used

Oral medicine

Some women prefer oral medicine rather than vaginal administration.

Especially for pregnant women who are high-risk for preterm labour, only oral medicines are used to treat bacterial vaginosis. Some doctors recommend that all pregnant women avoid vaginal treatment.

Vaginal medicine

Vaginal medicines are less likely than the oral forms to cause systemic side effects, such as nausea and vomiting.

How Well It Works

Women who aren't pregnant

Oral or vaginal metronidazole and vaginal clindamycin cream all work well for curing bacterial vaginosis.1 Vaginal or oral metronidazole cures bacterial vaginosis in as many as 9 out of 10 cases.2 Oral clindamycin has not been as well studied.

Although medicine usually cures bacterial vaginosis, it often comes back. Some doctors have women use medicine for a longer time to prevent this. 1

The Public Health Agency of Canada also recommends clindamycin cream 2% for 7 days.3 Clindamycin's relapse rate is higher: 4 weeks after clindamycin treatment, 56% of women have recurring bacterial vaginosis.4

Women who are pregnant

Oral antibiotics, such as metronidazole, work well for curing bacterial vaginosis during pregnancy.5

Side Effects

Vaginal medicines

Side effects of vaginal clindamycin and metronidazole are generally minor. The most common is a vaginal yeast infection during or after treatment.

The oil in clindamycin cream can weaken latex. This means condoms and diaphragms may break, and you may not be protected from STIs or pregnancy.

Oral medicines

Oral treatment can cause:

  • Unpleasant metallic taste in the mouth (common with metronidazole.).
  • Nausea.
  • Vomiting.
  • Diarrhea.

Completely avoid alcohol use (including alcohol-based non-prescription medicines, such as NyQuil) while you are taking metronidazole, because combining alcohol with this medicine may cause severe nausea and vomiting.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

During pregnancy

The Society of Obstetricians and Gynaecologists of Canada recommends treatment for bacterial vaginosis at any time during pregnancy.6

Either oral metronidazole or oral clindamycin are used for treatment during the second and third trimester of pregnancy. Neither medicine is likely to cause any harm to the fetus.1, 2

  • Metronidazole has been well studied and is generally thought to be safe to use during pregnancy.
  • Clindamycin vaginal cream is not recommended for bacterial vaginosis treatment in pregnant women. The cream form of clindamycin has been shown to have a slightly increased risk for preterm birth.2

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.



  1. Centers for Disease Control and Prevention (2006). Diseases characterized by vaginal discharge section of Sexually transmitted diseases treatment guidelines. MMWR, 55(RR-11): 49–56.
  2. Hillier S, et al. (2008). Bacterial vaginosis. In KK Holmes et al., eds., Sexually Transmitted Diseases, 4th ed., pp. 737–768. New York: McGraw-Hill.
  3. Expert Working Group on Canadian Guidelines for Sexually Transmitted Infections (2006, updated 2008). Canadian Guidelines on Sexually Transmitted Infections. Ottawa: Health Canada. Available online:
  4. Koumans EH, et al (2002). Indications for therapy and treatment recommendations for bacterial vaginosis in nonpregnant and pregnant women: A synthesis of data. Clinical Infectious Diseases, 35(Suppl 2): S152–S172.
  5. McDonald HM, et al. (2007). Antibiotics for treating bacterial vaginosis in pregnancy. Cochrane Database of Systematic Reviews (1).
  6. Yudin M, et al. (2008). Screening and management of bacterial vaginosis in pregnancy. SOGC Guideline No. 211. Journal of Obstetrics and Gynaecology Canada, 30(8): 702–708. Available online:


By Healthwise Staff
Primary Medical Reviewer Sarah Anne Marshall, MD - Family Medicine
Primary Medical Reviewer Donald Sproule, MD, CM, CCFP, FCFP - Family Medicine
Specialist Medical Reviewer Jeanne Marrazzo, MD, MPH - Infectious Disease
Last Revised April 13, 2010

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