Bacterial vaginosis

Image: BlurryMe/

Key points

  • Women may get bacterial vaginosis when the balance of normal bacteria in their vagina becomes disrupted.
  • It is common and various activities seem to increase the risk.
  • Having bacterial vaginosis increases the risk of getting a sexually transmitted infection, including HIV, or passing one on to sexual partners.

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 can be accompanied by unpleasant symptoms. It is a very common condition and can affect any woman. It is not a sexually transmitted infection (STI), and is easily treated with antibiotics.

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

Causes of bacterial vaginosis

The causes of bacterial vaginosis are not completely understood. It is not sexually transmitted, as it is not caused by bacteria passed on during sexual activity, but sexual activity may be part of the cause. However, it is possible to get it without having any sexual activity. These activities can increase the risk of a woman developing bacterial vaginosis:

  • having a new sexual partner or several sexual partners
  • washing the vagina (douching) and using soap or vaginal deodorant
  • smoking
  • being given oral sex (licking of the vagina)
  • using bubble bath, shower gel, scented soaps or antiseptic washes
  • having an intrauterine device (IUD) fitted.

"Bacterial vaginosis is not sexually transmitted, as it is not caused by bacteria passed on during sexual activity, but sexual activity may be part of the cause."

Bacterial vaginosis is common in women who are pregnant.


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. This may be worse after sex.


You can see your GP or go to a sexual health clinic. A doctor or nurse will examine you to look for signs of bacterial vaginosis. They may also test you for sexually transmitted infections if the symptoms are similar. 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.


Bacterial vaginosis sometimes goes away by itself as the balance of bacteria in the vagina corrects itself. If bacterial vaginosis is not bothering you, it is not always necessary to have it treated. However, it can increase the chance of passing on or acquiring HIV. You are advised to be treated if you have HIV and your partner does not, or the other way around. It is also important to be treated if you are going to have a surgical procedure that involves going through the neck of your womb (the cervix). If bacterial vaginosis is transmitted from the cervix into the womb during a procedure, you can develop a serious condition called pelvic inflammatory disease.

If you are pregnant or thinking about becoming pregnant, you may also want to be treated. There is some evidence that bacterial vaginosis can increase the risk of premature birth, especially if you have had a miscarriage, premature baby or baby with a low birth weight before.


bacterial vaginosis

A condition caused by the overgrowth of certain species of the bacteria that are normally present in the vagina.


Any perceptible, subjective change in the body or its functions that signals the presence of a disease or condition, as reported by the patient.



Single-celled micro-organisms.

sexually transmitted infections (STIs)

Although HIV can be sexually transmitted, the term is most often used to refer to chlamydia, gonorrhoea, syphilis, herpes, scabies, trichomonas vaginalis, etc.


Antibiotics, also known as antibacterials, are medications that destroy or slow down the growth of bacteria. They are used to treat diseases caused by bacteria.

You can safely take treatment during pregnancy. There is also a greater risk of passing on HIV to a baby during delivery.

Treatment is with an antibiotic called metronidazole. It can be given as tablets (a single larger dose or doses over seven days) or a vaginal gel over five to seven days. It’s important that you take all the treatment prescribed to you. You will need to avoid alcohol during treatment and for 48 hours after you have finished it, as it will make you feel very sick. If you use the vaginal gel, you will need to use non-latex condoms.

It is common for bacterial vaginosis to recur after treatment, so you may require another course of treatment at a later date. If you have frequent bouts of bacterial vaginosis, your doctor may recommend preventive treatment with antibiotics.

Next review date