What Is Bacterial Vaginosis?

Facts Every Woman Should Know

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Bacterial vaginosis (BV) is a common but frustrating condition in which the normal balance of the vaginal flora is disrupted, leading to an overgrowth of anaerobic bacteria. Symptoms include itchiness, vaginal discharge, and an unpleasant odor. While BV is readily treated with antibiotics, the recurrence of infection is common, usually within 12 months of treatment. BV tends to affect women in their childbearing years and is often associated with douching, unprotected sex, multiple sex partners, and other risk factors.

bacterial vaginosis symptoms
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Bacterial Vaginosis Symptoms

Of the 21 million American women believed to be affected by bacterial vaginosis each year, only around three million actually experience symptoms. When they occur, BV symptoms tend to mild but persistent and may include:

  • A grayish white or yellow vaginal discharge
  • A "fishy" smell that can get worse after intercourse
  • A burning sensation when urinating
  • Vaginal itchiness, redness, and swelling
  • Vaginal bleeding after intercourse

Less commonly, a BV infection may lead to urination problems, pain during sex, and the development of pelvic inflammatory disease (PID).

While BV symptoms are rarely serious, they can undermine the integrity of vaginal tissues and increase your vulnerability to sexually transmitted diseases (STDs) such as gonorrheachlamydiatrichomoniasis, and HIV.

Moreover, if an infection occurs during pregnancy, you may run an increased risk of preterm birth, low birth weight, and, in rare instances, a second-trimester miscarriage.


Bacterial vaginosis occurs when healthy bacteria in the vagina are depleted, allowing unhealthy ones to predominate and cause infection. Gardnerella vaginalis is one of the most common of these "bad" bacterias, but others can cause infection, too.

This imbalance can be caused by changes in the vaginal acidity or problems with the immune response, both of which decrease the body's ability to control the bacterial overgrowth. Sex can often instigate an infection by introducing new or excessive microbes into the vagina.

Some of the more common causes of BV include:

  • Unprotected oral, vaginal, or anal sex
  • Multiple sex partners
  • New sex partners
  • Shared sex toys
  • Douching
  • Smoking
  • Intrauterine devices (IUDs)

Genetics are also believed to play a part, either by promoting inflammation or by causing lower-than-expected levels of protective Lactobacilli in the vagina.


Since bacterial vaginosis is not caused by a single agent, a diagnosis would be made based on an evaluation of your symptoms and your various lab test results. This would generally involve:

  • A review of medical history
  • A pelvic exam
  • A pH test to check for vaginal acidity
  • A microscopic evaluation of your vaginal secretions

The microscopic exam would either look for "clue cells" (vaginal cells studded with bacteria) or use a gram stain to help differentiate the bacterial types and measure the proportion of "good" bacteria to "bad" ones. Based on a review of criteria, a doctor can either confirm the diagnosis or perform other tests to ensure that it's not some other illness (such as a yeast infection or genital herpes).

Home-based tests are also available but tend to be far less accurate.


The standard treatment for bacterial vaginosis is a short course of antibiotic drugs . The types used in first-line therapy, called metronidazole and clindamycin, are highly effective in treating BV and have relatively mild side effects.

The preferred first-line regimens include:

  • Metronidazole 500 milligrams taken by mouth twice daily for seven days
  • Metronidazole 0.75 percent vaginal gel applied once daily for five days
  • Clindamycin 2.0 percent vaginal cream applied at bedtime for seven days

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Alternative options include a clindamycin vaginal suppository or tinidazole tablets.  Despite the efficacy of treatment, recurrence is common and may require additional or even multiple treatments to achieve control.

Common side effects include nausea, stomachache, cough, sore throat, runny nose, and a metallic taste in the mouth.

In addition to prescription antibiotics, there are a number of home and supportive remedies that may help. They include probiotics (found in nutritional supplements and foods like yogurt) which may help prevent recurrence, and boric acid, an old-time remedy experiencing a resurgence in medical interest.


As common as bacterial vaginosis is, there are things you can do to reduce your risk. They include safer sex practices to avoid exposure to harmful bacteria and practicing good vaginal hygiene to reduce your odds of infection.

To prevent bacterial vaginosis:

  • Limit your number of sex partners.
  • Use protection for oral, vaginal, or anal sex, including condoms and dental dams.
  • Do not douche.
  • Wipe from front to back after urinating.
  • Avoid IUDs if you have recurrent BV or a past severe infection.

A Word From Verywell

Even with the best prevention efforts, bacterial vaginosis can sometimes occur. Try not to stress out. Instead, seek treatment and make every effort to avoid exacerbating the condition.

If the symptoms are driving you to distraction, make your life easier by ditching the tight pants and wearing looser clothing or a skirt. To treat an itch, apply a cold cloth directly to the vagina or splash with cold water in the shower. Scratching will only make things worse.

Finally, if you are being treated with antibiotics, do not stop halfway through even if your symptoms disappear. Doing so can increase the risk of antibiotic resistance and make treatment all the more difficult if the infection does, in fact, return.

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14 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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