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Bacterial vaginosis: Overview

Created: ; Last Update: August 9, 2018; Next update: 2021.


In bacterial vaginosis (sometimes abbreviated as BV), much larger than normal numbers of bacteria grow inside of the vagina.

This increase in bacteria is usually not dangerous and it often goes unnoticed, but it can cause a strong-smelling vaginal discharge and be very unpleasant. It also increases the risk of vaginal inflammation. Antibiotics can provide effective treatment.


At least half of the women who develop bacterial vaginosis do not have any noticeable symptoms. When the condition is detected, it is usually by a very unpleasant, thin, grayish-white vaginal discharge that smells strongly of fish. This smell is often stronger after sex or during menstruation.

Symptoms like itching, a burning sensation and vaginal dryness are more likely signs of vaginitis (an inflammation of the vagina). In that case the area around the vagina is usually reddened and the mucous lining of the vagina is swollen. There may also be problems when urinating (peeing) or during sex.


The vagina mostly contains lactic acid bacteria (LAB). Together with other bacteria they make up the vaginal flora and help to maintain a slightly acidic environment. The right acidity (pH level) can help to protect against germs. Bacterial vaginosis is caused by an imbalance in this acidic environment: The number of lactic acid bacteria drops and other vaginal flora bacteria can reproduce quickly. Bacterial vaginosis is most commonly caused by bacteria called Gardnerella vaginalis.

Risk factors

The risk of bacterial vaginosis is higher in women who are very sexually active and have a new partner or switch partners frequently.

Excessive intimate hygiene or hormonal changes can cause an imbalance in the vaginal flora and make vaginosis more likely.

Prevalence and outlook

Bacterial vaginosis is one of the most common types of vaginal infection. It is estimated that it affects about 5 out of 100 women. The infection clears up on its own in about one third of women. Treatment is usually needed if it causes symptoms.


If there is an imbalance in the vaginal flora, it's easier for other germs to grow there. This is why bacterial vaginosis can cause vaginal inflammation, and then also lead to infections in the womb (uterus) and fallopian tubes. The risk of contracting sexually transmitted diseases also increases.

Vaginal infections can also slightly increase the risk of complications such as early contractions, miscarriage, or premature birth in pregnant women.


It's not always possible to tell bacterial vaginosis from other types of vaginal infections based only on the symptoms. To diagnose vaginosis, a gynecologist examines the vagina and takes a sample of the secretion. This sample (“smear”) can be used to measure the pH level to find out what types of bacteria it contains. Samples from women with bacterial vaginosis usually have high levels of gardnerella bacteria.


Symptomatic bacterial vaginosis is usually treated with antibiotics to kill the germs. Treatments are available in tablet form or as a suppository or cream for direct application. It's not necessary to treat your partner, though – the treatment doesn't prevent future infection.

Another treatment option is suppositories or capsules containing living lactic acid bacteria. These treatments are designed to protect the vaginal flora and restore the correct balance. There is not yet enough evidence on the benefits of this method.

Some women also try things like putting tampons that have been soaked in tea tree oil or natural yogurt in their vagina to create a more acidic environment for the vaginal flora, but there has not yet been any research about how effective or safe these kinds of home remedies are.


© IQWiG (Institute for Quality and Efficiency in Health Care)
Bookshelf ID: NBK298829


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