Bacterial Vaginosis (BV)

What is bacterial vaginosis?

Bacterial vaginosis (BV) is a condition in women where the normal balance of bacteria in the vagina is disrupted and replaced by an overgrowth of certain bacteria. It is sometimes accompanied by discharge, odor, pain, itching or burning.

How common is bacterial vaginosis?

Bacterial vaginosis (BV) is the most common vaginal infection in women of childbearing age. In the United States, BV is common in pregnant women.

How do people get bacterial vaginosis?

The cause of BV is not fully understood. BV is associated with an imbalance in the bacteria that are normally found in a woman's vagina. The vagina normally contains mostly "good" bacteria, and fewer "harmful" bacteria. BV develops when there is an increase in harmful bacteria.

Not much is known about how women get BV. There are many unanswered questions about the role that harmful bacteria play in causing BV. Any woman can get BV. However, some activities or behaviors can upset the normal balance of bacteria in the vagina and put women at increased risk including:

  • Having a new sex partner or multiple sex partners
  • Douching
  • Using an intrauterine device (IUD) for contraception

It is not clear what role sexual activity plays in the development of BV. Women do not get BV from toilet seats, bedding, swimming pools, or from touching objects around them. Women who have never had sexual intercourse may be affected.

What are the signs and symptoms of bacterial vaginosis?

Women with BV often have an abnormal vaginal discharge with an unpleasant odor. Some women report a strong fish-like odor, especially after intercourse. The discharge is usually white or gray; it can be thin. Women with BV may have burning during urination or itching around the outside of the vagina, or both. Some women with BV report no signs or symptoms at all.

How is bacterial vaginosis diagnosed?

A health care provider must examine the vagina for signs of BV (e.g., discharge) and perform laboratory tests on a sample of vaginal fluid to look for bacteria associated with BV.

What are the complications of bacterial vaginosis?

In most cases, BV causes no complications. But there are some serious risks from BV including:

  • Having BV can increase a woman's susceptibility to HIV infection if she is exposed to the HIV virus.
  • Having BV increases the chances that an HIV-infected woman can pass HIV to her sex partner.
  • Having BV has been associated with an increase in the development of an infection following surgical procedures such as a hysterectomy or an abortion.
  • Having BV while pregnant may put a woman at increased risk for some complications of pregnancy, such as preterm delivery.
  • BV can increase a woman's susceptibility to other STDs, such as herpes simplex virus (HSV), chlamydia and gonorrhea.

How does bacterial vaginosis affect a pregnant woman and her baby?

Pregnant women with BV more often have babies who are born premature or with low birth weight (low birth weight is less than 5.5 pounds).

The bacteria that cause BV can sometimes infect the uterus (womb) and fallopian tubes (tubes that carry eggs from the ovaries to the uterus). This type of infection is called pelvic inflammatory disease (PID). PID can cause infertility or damage the fallopian tubes enough to increase the future risk of ectopic pregnancy and infertility. Ectopic pregnancy is a life-threatening condition in which a fertilized egg grows outside the uterus, usually in a fallopian tube which can rupture.

Who should be treated for bacterial vaginosis?

Although BV will sometimes clear up without treatment, all women diagnosed with BV should be treated to avoid such complications as PID. Treatment is especially important for pregnant women. All pregnant women, regardless of symptoms, who have ever had a premature delivery or low birth weight baby should be considered for a BV examination and be treated when necessary. All pregnant women who have symptoms of BV should be checked and treated. Male partners generally do not need to be treated. However, BV may spread between female sex partners.

Treatment is especially important for pregnant women. All pregnant women who have ever had a premature delivery or low birth weight baby should be considered for a BV examination, regardless of symptoms, and should be treated if they have BV. All pregnant women who have symptoms of BV should be checked and treated.

Some physicians recommend that all women undergoing a hysterectomy or abortion be treated for BV prior to the procedure, regardless of symptoms, to reduce their risk of developing an infection.

BV is treatable with antibiotics prescribed by a health care provider. Two different antibiotics are recommended as treatment for BV: metronidazole or clindamycin. Either can be used with non-pregnant or pregnant women, but the recommended dosages differ. Women with BV who are HIV-positive should receive the same treatment as those who are HIV-negative.

How can bacterial vaginosis be prevented?

BV is not completely understood by scientists, and the best ways to prevent it are unknown. However, it is known that BV is associated with having a new sex partner or having multiple sex partners.

The following basic prevention steps can help reduce the risk of upsetting the natural balance of bacteria in the vagina and developing BV:

  • Be abstinent.
  • Limit the number of sex partners.
  • Do not douche.
  • Use all of the medicine prescribed for treatment of BV, even if the signs and symptoms go away.

Where can I get more information?

Illinois Department of Public Health

IDPH HIV/STD Hotline 800-243-2437 (TTY 800-782-0423)

U.S. Centers for Disease Control and Prevention (CDC)
CDC-INFO Hotline (7am-7pm Mon.-Fri. Closed Holidays)

STD information and referrals to STD Clinics
800-CDC-INFO (800-232-4636)
TTY: 888-232-6348
In English, en Español

CDC National Prevention Information Network (NPIN)
P.O. Box 6003
Rockville, MD 20849-6003
888-282-7681 Fax

American Social Health Association (ASHA)
P. O. Box 13827
Research Triangle Park, NC 27709-3827

May 2013


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Illinois Department of Public Health
535 West Jefferson Street
Springfield, Illinois 62761
Phone 217-782-4977
Fax 217-782-3987
TTY 800-547-0466
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