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What are the symptoms of bacterial vaginosis?

Bacterial vaginosis is one of the most common vaginal infections. It causes a discharge which is usually watery thin and white or gray-coloured. The discharge often has an unpleasant fishy smell- which points to the diagnosis.

The main symptom of bacterial vaginosis (BV) is a vaginal discharge.

This discharge is usually:

  • Thin and white or grey-coloured - watery in consistency.

  • Smelly - it typically smells fishy and unpleasant.

BV usually doesn't cause vaginal or vulval itching or soreness - but it can do sometimes.

If you think you have bacterial vaginosis, find out what to do here.

In this series of articles centred around bacterial vaginosis (BV), you can read about BV symptoms, BV causes, and BV treatments - all written by one of our expert GPs.

The rest of this feature will take an in-depth look at the symptoms of bacterial vaginosis, as at Patient, we know our readers sometimes want to have a deep dive into certain topics.

Continue reading below

What are the symptoms of bacterial vaginosis?

Vaginal discharge

The main symptom of bacterial vaginosis is a vaginal discharge.

This discharge is typically watery and white or greyish. It tends to smell unpleasant. Typically, it has a fishy smell. The smell is sometimes worse after sex. Discharge tends to be heaviest after a period, or after sex.

BV usually doesn't commonly cause vaginal or vulval irritation, soreness, or pain. However, some women may experience some itching or irritation. It shouldn't cause unexpected vaginal bleeding either, although it can be worse during or after a period.

No symptoms

Research studies have tested women for BV-causing bacteria, such as a bacteria called Gardnerella vaginalis. In those studies, around one half of women with test results showing BV didn't have any symptoms.

It might be that the bacteria were causing mild symptoms that weren't very noticeable - or alternatively, that they were causing no symptoms at all.

The main aim of treating BV is to improve symptoms. So, testing and treating women for BV if they already have no symptoms isn't recommended, since it doesn't have any benefit.

Women who are pregnant might be offered BV treatment if they're found to have it, even if they don't have any symptoms. This is because BV is linked with a higher risk of problems in pregnancy.

However, we don't really know if treating BV reduces the risk of those problems - so it's generally not recommended to test anyone, including pregnant women, for BV if they have no symptoms.

Patient picks for Vaginal and vulval problems

When to see a doctor

See a doctor if you think you have BV. They can tell you if it is BV, and might offer tests for other causes of vaginal discharge as well. They can also give treatment to help resolve the symptoms quicker.

You can see your GP or a sexual health clinic - both are experienced with diagnosing and treating BV.

Continue reading below

How is bacterial vaginosis diagnosed?

Sometimes, BV can be diagnosed and treated based on the description of the symptoms alone.

Doctors might do this if:

  • You're at low risk of having a sexually transmitted infection.

  • This is the first time the symptoms have happened, or, you've been diagnosed with BV before and the symptoms are the same.

  • There are no symptoms that suggest another cause of vaginal discharge.

  • You haven't recently had, or are about to have, a gynaecological procedure or operation.

  • You haven't recently given birth, had a miscarriage, or had a termination of pregnancy.

  • You're not pregnant.

If they think it would be helpful, your doctor may suggest further tests. These can look for BV, but also look for other causes of vaginal discharge.

These include swab tests. Sometimes you might be given a swab to take yourself; other times, your doctor may suggest a speculum examination to look inside the vagina and at the cervix. This also allows them to take a sample of the discharge.

Tests that might be done include:

  • Testing the acidity of the vagina. The vagina is normally acidic with a pH below 4.5. When the pH rises above 4.5, bad bacteria such as Gardnerella grow rapidly in the vagina.

    • So, vaginal discharge with a pH above 4.5 suggests BV as the cause, although it can also be found in other conditions, such as trichomoniasis.

    • pH testing can be done by a doctor or nurse, and you can also buy self-test kits over the counter (such as Canestest).

  • Taking a swab of the vaginal discharge to look at the vaginal bacteria under a microscope. This looks at the amount of good bacteria (Lactobacilli) and bad bacteria (such as Gardnerella). This is usually reported as normal, indeterminate (in-between), or suggestive of BV.

    • The same swab can also be tested for Candida (thrush, also called a yeast infection), which is a different condition that tends to cause a white, cottage cheese-like vaginal discharge.

  • Taking a swab to look for sexually transmitted infections, such as Chlamydia, Gonorrhoea, and sometimes Trichomonas. These can also cause a vaginal discharge, and also might also be recommended as a general checkup if you are sexually active.

  • Blood tests for HIV and syphilis. These don't cause BV symptoms, but may be recommended as a general checkup if you are sexually active.

It's a good idea for anyone who is sexually active to get regular checkups for sexually transmitted infections. They can be carried without having any symptoms, and are easily treatable if diagnosed.

Article history

The information on this page is peer reviewed by qualified clinicians.

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