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Bacterial vaginosis

Michael Carter, Greta Hughson
Published: 17 May 2012

Bacterial vaginosis (BV) is a condition which occurs when the normal balance of bacteria in the vagina becomes disrupted.

This can result in an over-growth of certain bacteria, which is often accompanied by unpleasant symptoms. It is a very common condition, thought to affect one in three women at some point in their lives.

Women with bacterial vaginosis may be at increased risk of infection with HIV. There is also evidence that HIV-positive women who have bacterial vaginosis when they give birth are at greater risk of passing on HIV to their baby and the sexual partners of HIV-positive women who have bacterial vaginosis are more likely to become infected with HIV.

Causes of bacterial vaginosis

Washing the vagina (douching) is a common cause of bacterial vaginosis. Douching and using soap or vaginal deodarant can upset the balance of bacteria. Smoking, using bubble bath and having an intrauterine device (IUD) fitted have also been associated with an increased risk of bacterial vaginosis.

A general sexual health check-up will include tests for bacterial vaginosis.

Although bacterial vaginosis is sometimes referred to as a sexually transmitted infection, this classification is not strictly correct. You do not 'catch' bacterial vaginosis, as it is not caused by bacteria which are usually transmitted sexually. Having a new sexual partner or multiple sexual partners, however, can also put women at increased risk of developing bacterial vaginosis.


Many women with bacterial vaginosis have no symptoms at all. When they do occur, symptoms can include changes to vaginal discharge, such as it becoming grey or whitish, watery or developing a fishy smell. Other symptoms can include pain passing urine and pain during sex.

If bacterial vaginosis is left untreated, it can cause more serious symptoms and even lead to infertility or a potentially serious condition called pelvic inflammatory disease.


A general sexual health check-up will include tests for bacterial vaginosis. A doctor or nurse will examine you to look for signs of bacterial vaginosis and other sexually transmitted infections. A swab will probably be taken from the vagina and will be examined under a microscope to see if you have bacterial vaginosis or any other infection.

Sexual health screens are freely available from NHS genitourinary medicine (GUM) and sexual health clinics. Many HIV clinics also provide sexual health screens and tests for bacterial vaginosis as part of their routine care.

You can also see your GP about any symptoms.

Bacterial vaginosis and health complications

If you are pregnant and have symptoms of bacterial vaginosis, it is very important to see your GP or another health service so that you can be treated. Untreated bacterial vaginosis can cause complications in pregnancy, including premature birth and miscarriage.

Women with HIV who have bacterial vaginosis may be more likely to pass on HIV during sex and there is also a greater risk of passing on HIV to a baby during delivery.

If you have bacterial vaginosis, you are at greater risk of becoming infected with other sexually transmitted infections and there is a possibility that pelvic inflammatory disease, which is potentially very serious, could also occur if bacterial vaginosis is left untreated.


Although bacterial vaginosis sometimes goes away by itself as the balance of bacteria in the vagina corrects itself, it is important that HIV-positive women who believe that they may have the condition are screened for it and if necessary take treatment.

It is particularly important that women who are pregnant or thinking about pregnancy have their symptoms investigated and, if necessary, are treated.

Treatment is with antibiotics. Metronidazole can be used as an oral treatment. Treatment usually lasts for seven days and consists of twice-daily doses of 400mg. An alternative oral metronidazole treatment is a single 2g dose. Another possible treatment is an antibiotic gel applied in the vagina once a day for five days. Metronidazole is available in a gel formulation, as is an antibiotic called clindamycin. It’s important that you take all the treatment prescribed to you.

Bacterial vaginosis can recur after treatment so you may require another course of treatment at a later date.

Contact NAM to find out more about the scientific research and information used to produce this factsheet.

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.
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