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Bacterial Vaginosis

Bacterial vaginosis (BV) is the commonest cause of abnormal vaginal discharge. It is caused by a change in the number and type of bacteria found in the vagina. A healthy vagina contains many different types of bacteria. In BV there is a decrease in the number of a particular bacteria called lactobacilli, and an increase in other bacteria called anaerobic bacteria.

The increase in the anaerobic bacteria changes the chemistry of the vaginal fluid making it more alkaline. One in ten will have BV at some time in their life. BV is associated with sex but is not considered a sexually transmissible infection. Having a new sexual partner or multiple partners, and douching (rinsing inside the vagina) all increase the risk of getting BV.


50% of people with bacterial vaginosis will have no symptoms. If symptoms do occur they include:

  • Increased or changed vaginal discharge. (often white or grey watery)
  • Vaginal odour - usually slightly offensive or ‘fishy’. The odour maybe more noticeable after sex.
  • Itching or mild vulval irritation.


BV is usually diagnosed by a doctor based on symptoms and an examination, and is usually confirmed with a vaginal swab.


BV is not considered a sexually transmissible infection as there is not a known link with sexual transmission. However there does seem to be some association with it occurring when there is a new sexual partner, or when there are multiple sexual partners. There seems to be a decrease in occurrence when condoms are used consistently.


In up to one third of cases BV resolves without treatment. Treatment is advised to relieve symptoms which persist, if you are planning to have a gynaecological procedure, or if you are pregnant.

BV is treated with antibiotics. These antibiotics reduce the anaerobic bacteria and allow the lactobacilli increase in number and to restore normal balance in the vagina. Antibiotics can be given as oral tablets, vaginal creams, or vaginal gels. Please discuss with your doctor your preferred method.

Some individuals may experience side effects such as abdominal pain, cramps, nausea & vomiting, flushing, or headache when taking treatment for bacterial vaginosis. Depending on which medication is used, you may be advised to avoid alcohol during treatment, and for up to 3 days afterwards.

The vaginal preparations weaken latex condoms so no sex or non-latex condom use is advised during treatment.


  • Someone who has BV whilst pregnant is at risk of late miscarriage, premature birth, and developing a womb infection after birth.
  • Someone with BV who undergoes gynaecological procedures is at greater risk of developing a pelvic infection.
  • Someone with BV has an increased risk of getting a sexually transmitted infection including HIV, chlamydia, and herpes.


About a third who respond to treatment will have another episode of BV within three months, more than half will have a recurrence within a year.

The best ways of preventing BV are not known. Avoiding anything that changes the balance of vaginal bacteria may help. You may reduce the chance of getting BV if you avoid the following:

  • Scented soap, shower gels, perfumed bubble bath, and antiseptic bath liquids
  • Vaginal douching
  • Using any commercial ‘feminine hygiene’ products such as sprays, vaginal deodorants, washes or wipes.

Using condoms also reduces your risk of developing BV.


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Last updated November 2018

Australian STI Management Guidelines for use in primary care.
Melbourne Sexual Health Centre.