Diseases & Conditions

Bacterial Vaginosis

Overview, Causes, & Risk Factors

Bacterial vaginosis is a swelling and irritation of the vaginal tissue.

What is going on in the body?

Bacterial vaginosis appears to be caused by an overgrowth of several types of bacteria, some requiring oxygen while others do not. While these bacteria are normally present in the vagina, an overgrowth may cause symptoms of irritation and inflammation.

What are the causes and risks of the disease?

It is not known for sure what causes this condition. It is probably caused by an overgrowth of certain bacteria that are normally present in the vagina.

Bacterial vaginosis that is left untreated or undiagnosed can cause more problems. For instance:

  • A woman having surgery to remove her uterus, called a hysterectomy, can develop an infection around the edge of the vagina if she has this condition.
  • A pregnant woman may have her membranes break early and go into premature labor if this condition is not treated.

  • Symptoms & Signs

    What are the signs and symptoms of the disease?

    Symptoms of this condition can include:

  • a fishy or ammonia-like odor, especially after sexual intercourse
  • vaginal itching, burning, or irritation
  • pain with intercourse
  • vaginal discharge

  • Diagnosis & Tests

    How is the disease diagnosed?

    A healthcare provider will perform a pelvic exam to obtain a sample of the vaginal discharge and look at it under the microscope. A blood test also will be done. The presence of special "clue cells" in the vaginal discharge, along with a high white blood cell count, suggest bacterial vaginosis.

    Prevention & Expectations

    What can be done to prevent the disease?

    It is not known how to prevent this condition. It is possible that abstinence or using condoms may help.

    What are the risks to others?

    It is possible that this infection is spread by sexual intercourse.

    Treatment & Monitoring

    What are the treatments for the disease?

    The antibiotic metronidazole is used to treat this type of vaginitis. It is available in orals pills or as a cream that is applied to the inside of the vagina. It is usually taken for 5 to 7 days. The sexual partner may be treated, depending on the number of previous infections.

    What are the side effects of the treatments?

    The side effects of metronidazole can include:

  • a metallic taste in the mouth
  • ringing in the ears
  • stomach upset if alcohol is ingested at the same time
  • What happens after treatment for the disease?

    After beginning treatment, symptoms usually go away within a few days. The infection recurs in 15% of women despite attempts at prevention and multiple treatment regimens.


    Author:Eva Martin, MD
    Date Written:
    Editor:Cafiero, Celeste, MA
    Edit Date:05/19/00
    Reviewer:Sandy Keefe, RN, MSN
    Date Reviewed:09/19/01