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B.V. (Bacterial Vaginosis)

Bacterial vaginosis (known as BV) is a common yet poorly understood condition in which the balance of bacteria inside the vagina becomes disrupted.

Around one in three women will experience at least one episode of BV at some point.

This imbalance often triggers a change to the usual vaginal discharge, which results in a fishy smelling, greyish discharge from the vagina. However, half of women with bacterial vaginosis have no symptoms.

What causes BV?

The vagina contains a mix of so-called "good" bacteria, which can help protect against infection, and a smaller amount of "bad" bacteria, which can cause infection.

In cases of BV, the bad bacteria begin to outnumber the good bacteria, leading to inflammation inside the vagina, which can result in the fishy discharge. What leads to this imbalance is still unclear. It is not classed as a typical sexually transmitted infection, but it can develop after having sex with a new partner, especially amongst women who have sex with women.

You can also get BV if you:

  • Use scented soaps or bubble baths
  • Have an intrauterine device (IUD)
  • Smoke
  • Use vaginal deodorant


The main symptom of BV is a change in your usual vaginal discharge.

Your discharge may:

  • Become thin and watery
  • Change to a white or grey colour
  • Develop a strong, unpleasant, fishy smell, particularly after sex

Other symptoms of BV can include:

  • Pain during sex
  • Pain when passing urine
  • Some light bleeding from your vagina

BV does not usually cause itching or irritation.

Around half of all women with BV do not have any symptoms (known as asymptomatic BV).

If you do not have symptoms, there is no need to get tested to find out if you have BV as asymptomatic BV does not pose a threat to your health or pregnancy.

Do you think you may have BV?

If you think you may have BV you can go to your nearest GUM clinic. You can also see your local GP.

By law, a sexual health clinic cannot tell anyone about your visit to the GUM; these rules do not apply to your GP who can tell other people about your appointment.


Your doctor may diagnose BV from a description of your symptoms and by examining your vagina. In particular, they will look for:

  • A thin, greyish discharge
  • An unpleasant smell

In some cases, this may be enough to confirm your diagnosis. However, if you are sexually active and may have a sexually transmitted infection instead of BV, you might need further tests.

Testing will involve using a swab (like a cotton bud) to take a sample of cells from the vagina, the genital area and the urethra. It only takes a few seconds and is not usually painful, although it may be slightly uncomfortable.


To treat BV you will need to complete a course of antibiotics.

If your BV symptoms disappear after treatment, you will not need to be tested for BV again to confirm that the treatment has worked. However, you will need to be tested again if:

  • Your symptoms do not go away
  • Your symptoms return
  • You are treated for BV while you are pregnant

Why is treatment important?

Treatment is important because pregnant women with untreated BV, that is causing symptoms, have a higher risk of developing complications that can affect pregnancy. There is also evidence that having BV can make you more at risk of catching other STIs.

No one is immune to BV, if you have had it you can get it again.

Protect yourself and others

Using a condom for penetrative sex or sharing sex toys can help protect against getting and passing on BV, or other sexually transmitted infections. Dental dams can also be used during oral sex and rimming for safer sex. You can order free safer sex packs from Trade here.

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