Bacterial vaginosis (BV) is the most common of three vaginal infections that fall under the category known as vaginitis. The other two infections are trichomoniasis, a sexually transmitted disease, and the fungal infection commonly known as a yeast infection.

BV is the least understood and most often ignored or misdiagnosed of these conditions. However, it is gaining more attention as more research shows that untreated BV can lead to significant health complications, including premature delivery, postpartum infections, clinically apparent and subclinical pelvic inflammatory disease (PID), postsurgical complications (after abortion, hysterectomy, cesarean section and other reproductive procedures), increased vulnerability to HIV infection and, possibly, infertility. As many as one-third of women in the United States have BV.

BV is not considered a sexually transmitted disease, although it is less common in women who have never had sex. There is evidence that it could be linked to having a new sex partner or multiple sex partners. Also, douching appears to increase the risk of developing BV.

BV has gone by different names in the past, including nonspecific vaginitis and Gardnerella vaginalis vaginitis. BV is simpler to remember, but there is nothing simple about this condition, and it is not harmless, as was once believed.

BV is actually a syndrome resulting from an imbalance in the different types of bacteria in the vagina (also called vaginal "flora"). A healthy vagina has numerous organisms that naturally live there. The vast majority—about 95 percent—belong to a type of bacteria called lactobacillus.

There are several kinds of lactobacillus, at least one of which is responsible for keeping the vagina's pH at normal levels. One hypothesis claims that when these levels become unbalanced, certain microorganisms may overtake the normal flora leading to a low-grade infection that often produces an abnormal vaginal discharge.


With many negative outcomes now linked to bacterial vaginosis (BV), it is important that women get tested and treated. But surveys find that the majority of health care professionals don't routinely test for or treat BV. And yet an estimated 29 percent of women aged 14 to 49 and 50 percent of African American women have BV.

The most common symptoms include a discharge and an unpleasant vaginal odor. Women may easily mistake BV for a yeast infection, which is caused by the overgrowth of fungi called Candida albicans. However, BV requires a different treatment, so it is important you get an accurate diagnosis. Additionally, you may have more than one type of vaginitis at the same time, so having a yeast infection doesn't mean you can't also have BV.

Fortunately, a trained health care professional can easily diagnose BV. All it takes is a test to check the level of acidity, or pH, in the vagina. A vaginal pH greater than 4.5 is one sign that you may have BV.

Your health care professional will also take a vaginal discharge specimen for examination under a microscope to look for "clue cells"—cells from the vaginal lining that are covered with bacteria. It is important not to douche or use deodorant sprays before a medical exam because these products can make it more difficult to diagnose BV.

In addition to measuring the vaginal pH and checking for clue cells, your health care professional may place a drop of 10 percent potassium hydroxide on a vaginal fluid specimen and check the odor. Several commercial tests also are available to diagnose BV. Cultures for Gardnerella vaginalis alone and cervical Pap tests are not accurate methods for diagnosing BV.

The most common symptom of BV is a vaginal discharge similar in consistency and appearance to skim milk. The discharge caused by the infection often has a strong "fishy" odor that may become worse after sex because semen changes the acidic level of vaginal fluids. BV also may cause vaginal itching and irritation. About 50 to 75 percent of women with BV experience no symptoms.


As with other vaginal infections, the primary goal in treating bacterial vaginosis (BV) is to relieve signs and symptoms of infection. All women with symptoms should be treated.

BV is treated with antibiotics. The most common therapies are metronidazole (Flagyl), and clindamycin (Cleocin). Both metronidazole and clindamycin are available by prescription in oral (pill) form, and metronidazole is available in a gel (MetroGel-Vaginal), and clindamycin is available in a cream (such as Clindesse) that you insert into the vagina. Generic versions of these antibiotics also are available and effective.

If your symptoms disappear with treatment, you don't have to see your health care professional again. One round of treatment usually works in about 70 percent of cases. However, BV frequently recurs and can be chronic in some women.

Don't drink any alcohol while using metronidazole (either oral or vaginal) because it may make you nauseous and/or lead to severe vomiting. Also, if you're using intravaginal forms of clindamycin, the oil-based medication may weaken latex condoms or diaphragms. Topical clindamycin may rarely cause colitis, a potentially life-threatening infection of the colon.

Talk to your health care professional about this risk and be sure to alert him or her if you experience severe diarrhea, stomach cramping or blood in your stool while taking clindamycin or within a few weeks of stopping it. Over-the-counter treatments available for some vaginal infections (Candidiasis, or "yeast" infections) are NOT effective for BV.

While you're being treated for BV, you may be advised not to have sex; if you do have sex, your partner should wear condoms. Treating your male partner isn't necessary, however, since studies find it doesn't help prevent another infection. Female partners may need treatment, however.

Treatment is more complicated for pregnant women. If you've previously delivered a premature infant, you may be tested for BV during your first prenatal visit. If you have the infection, you should be treated promptly.

Regardless of other risk factors for preterm delivery, all symptomatic pregnant women should be tested and treated. However, most studies show no difference in risk of preterm delivery in asymptomatic women who don't get treated versus those who get treated. Thus, pregnant women with asymptomatic BV don't require treatment.

In any case, pregnant women who are going to be screened should have this done during the first prenatal visit.


Numerous factors may be associated with vaginal infections. Although no single factor has emerged as a primary cause, experts say healthy diets and behavior are the best medicine. Minimizing stress also is important.

One of the more disturbing aspects of bacterial vaginosis (BV) is that the infection frequently returns after treatment. About 30 percent of women have a recurrence within three months of treatment. While the reasons for recurrent BV are not well understood, long-term maintenance treatment may be recommended for women with frequent recurrences of BV.

However, you should take all prescribed medicines as recommended to decrease the likelihood of recurrence. Continue taking the medicine as you've been directed even if your symptoms disappear.

One cause of recurrent BV may be that even after the harmful bacteria that replaced the "good" bacteria is gone, the "good" bacteria have trouble growing back in the vagina.

Most women with recurrent BV infection respond well to therapies that help maintain the ratio of "good" to "bad" bacteria in the vagina. One such therapy is metronidazole gel (0.75 percent) for 10 days followed by an application twice a week for three to six months.

Here are some tips that may decrease the risk of BV or recurrent BV:

  • Don't douche. Douching upsets the normal pH balance of the vagina.
  • Avoid sexual contact with someone who has a sexually transmitted disease; use condoms if you're uncertain.
  • Avoid local irritants such as bubble baths, harsh soaps, feminine hygiene sprays and deodorant tampons, all of which can affect the normal pH of the vagina.
  • Reduce semen exposure (which can affect the vaginal bacteria balance) by using condoms.
  • Don't smoke.
  • After a few weeks of therapy for BV, ask your health care professional to retest you for the infection.
  • If you develop BV three or more times in a year, talk to your health care professional about alternating medications or using intravaginal metronidazole as a prophylactic for three to six months.

Facts to Know

1. Half of all African-American women aged 14 to 49 in the United States have BV. This may help explain why African-American women have higher rates of problem pregnancies. The reason for increased BV in this population is not clear.

2. BV is widespread but its prevalence varies widely. BV is the most common cause of vaginitis in women of childbearing age–almost one in three women in the United States has BV.

3. BV increases a woman's risk of delivering prematurely or delivering a baby with low birthweight. A National Institutes of Health study found that pregnant women with BV were more likely to deliver a baby with low birthweight than those without the infection. The most common cause of premature birth from BV is premature rupture of membranes.

4. A woman with BV may be more likely to become infected with HIV, the sexually transmitted virus that causes AIDS (acquired immunodeficiency syndrome). Recent studies have shown a relationship between BV and HIV, so health officials now consider BV a risk factor for HIV acquisition, particularly in developing countries where BV is often untreated.

5. Bacterial vaginosis infection disrupts the vaginal ecosystem. Some women infected with BV may have up to 1,000 times more anaerobic bacteria (bacteria that require no oxygen to live) than uninfected women. Once this imbalance occurs, the body has difficulty getting back to normal. Consequently, researchers are looking at natural ways to supplement the "good" bacteria needed to protect the genital tract from infection, and thereby reduce recurrences.

6. Because its symptoms mimic other vaginal infections, BV is often mistaken for a common yeast infection.

7. About 50 percent to 75 percent of women with BV have no symptoms. And yet studies find that as many as one-third of women entering obstetric clinics have a BV infection.

8. Despite adequate treatment, BV recurs in 30 percent of women within three months. Researchers are not sure what makes some women more prone to recurrent BV.

9. The greatest risk factors for BV are having a new sex partner or having multiple sex partners.

10. Probiotics currently available are not effective in preventing or curing BV.

Questions to Ask

Review the following Questions to Ask about bacterial vaginosis (BV) so you're prepared to discuss this important health issue with your health care professional.

  1. Do over-the-counter products work for treating and preventing BV?
  2. Does my male partner need to be treated?
  3. What if I have a female partner? Will she need to be treated?
  4. What difference does it make whether I have BV or a yeast infection?
  5. If I have had BV in the past and am pregnant, should I get tested for BV even if I don't have any symptoms?
  6. How do I identify BV and avoid it in the future?
  7. Do I need to refrain from sexual contact while I am being treated?
  8. How much douching is excessive?
  9. Are the drugs used for treating BV safe for pregnant women?
  10. Is BV considered a sexually transmitted infection?

Key Q&A

How do I know if I need to see my health care professional?

Pay attention to your body. If you experience symptoms, such as a change in the color and consistency of vaginal fluid, genital itching or burning, you may have a vaginal infection, which, if left untreated, can lead to health complications.

What makes bacterial vaginosis (BV) serious for women who are pregnant?

Studies have shown that women with untreated BV are at higher risk of delivering prematurely or giving birth to a low-weight baby. Not all vaginal infections cause pregnancy problems, but BV is potentially serious and requires attention. Screening and treatment is appropriate for pregnant women with symptomatic BV. Follow-up may be needed during the pregnancy.

Are all pregnant women treated for BV?

No. Regardless of other risk factors for preterm delivery, all pregnant women with BV who have symptoms should be treated. However, treating pregnant women who test positive for BV but who don't have symptoms (asymptomatic) is controversial. Generally, pregnant woman with asymptomatic BV don't require treatment.

What are my chances of having BV come back?

As many as 30 percent of women who have been treated for BV experience recurrences within 90 days of treatment. Not finishing your prescribed medicine can lead to a recurrence.

Why does excessive douching increase the risk of developing BV?

The healthy vaginal ecosystem requires the right balance of bacteria flora. Nearly 95 percent of the vaginal mucous membrane, which protects against bacteria and other pathogens, is made up of healthy bacteria called lactobacilli. These bacteria make natural acids that keep unhealthy bacteria from getting out of hand. Too much douching can disrupt the bacterial balance and lead to infection.

Can I treat BV with over-the-counter yeast infection medications?

No. Vaginal creams and suppositories for treatment of "yeast" (Candida) infections do not treat BV.

Why is it important to determine what type of vaginitis I have?

BV, trichomoniasis and candidiasis (yeast infection) are caused by different pathogens and must be treated differently. Each type of infection requires a specific treatment, and some infections have more than one cause.

What about diagnosing and treating BV in men?

Studies show there is no need to treat male sexual partners for BV, and clinical studies have shown that treating male partners with antibiotics doesn't affect a woman's risk of recurrence or her response to treatment.

Organizations and Support

For information and support on coping with Bacterial Vaginosis, please see the recommended organizations and Spanish-language resources listed below.

American College of Obstetricians and Gynecologists (ACOG)
Website: https://www.acog.org
Address: 409 12th Street, SW
P.O. Box 96920
Washington, DC 20090
Phone: 202-638-5577
Email: resources@acog.org

ASHA's STI Resource Center Hotline
Website: https://www.ashasexualhealth.org/person2person-2/
Address: American Social Health Association
P.O. Box 13827
Research Triangle Park, NC 27709
Hotline: 1-800-227-8922
Phone: 919-361-8400

CDC National Prevention Information Network
Website: https://www.cdcnpin.org
Address: P.O. Box 6003
Rockville, MD 20849
Hotline: 1-800-458-5231
Phone: 404-679-3860
Email: info@cdcnpin.org

Guttmacher Institute
Website: https://www.guttmacher.org
Address: 1301 Connecticut Avenue NW, Suite 700
Washington, DC 20036
Hotline: 1-877-823-0262
Phone: 202-296-4012
Email: info@guttmacher.org

National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention
Website: https://www.cdc.gov/nchhstp
Address: Centers for Disease Control and Prevention
1600 Clifton Road
Atlanta, GA 30333
Hotline: 1-800-CDC-INFO (1-800-232-4636)
Email: cdcinfo@cdc.gov

National Family Planning and Reproductive Health Association (NFPRHA)
Website: https://www.nationalfamilyplanning.org/
Address: 1627 K Street, NW, 12th Floor
Washington, DC 20006
Phone: 202-293-3114
Email: info@nfprha.org

Planned Parenthood Federation of America
Website: https://www.plannedparenthood.org
Address: 434 West 33rd Street
New York, NY 10001
Hotline: 1-800-230-PLAN (1-800-230-7526)
Phone: 212-541-7800

Spanish-language resources

Family Doctor
Website: https://familydoctor.org/online/famdoces/home/women/reproductive/vaginal/234.html

Centers for Disease Control and Prevention
Website: https://www.cdc.gov/std/spanish/vb/stdfact-bacterial-vaginosis-s.htm
Address: Centros para el Control y la Prevención de Enfermedades
P.O. Box 6003
Rockville, MD 20849
Hotline: 1-800-458-5231
Phone: 1-800-232-4636
Email: cdinfo@cdc.gov

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