Bacterial Vaginosis

What is bacterial vaginosis?

Bacterial vaginosis is an infection in a woman's vagina caused by an overgrowth of bacteria. It is normal to have bacteria within the vagina. However, with bacterial vaginosis, the 'normal or good' bacteria are taken over by other bacteria. This change in balance results in the symptoms some women experience.

How do you get bacterial vaginosis?

It is not completely understood why some women develop bacterial vaginosis . It is more common:  

  • in women with more than one sexual partner
  • when women change sexual partner
  • in women who have sex with other women.

It is also possible that the problem bacteria can be transmitted on fingers or sex toys.

What are the symptoms?

Some women have no symptoms and bacterial vaginosis is found during examination for something else such as a cervical smear test. Other times women notice an abnormal vaginal discharge or an unusual fishy odour which may be worse after unprotected sex.


Treatment for bacterial vaginosis varies depending on several factors. If a woman does not have any symptoms, in most cases no treatment is needed. However, if a woman is concerned about the smelly discharge or about to have a gynaecological procedure where the risk of infection spreading to the womb (uterus) is higher, then any bacterial vaginosis infection should be treated first.

Standard treatment for bacterial vaginosis is a seven-day course of metronidazole tablets. Metronidazole is an antibiotic and is best taken with meals to reduce possible side effects such as nausea or upset stomach. It is also important NOT to drink alcohol while taking metronidazole, otherwise people can suffer severe hangover effects.

Does my partner need to be treated?

Treating the male partner of an infected woman does not seem to prevent recurrences so is NOT routinely recommended. In a same sex female couple, some times treating both women is recommended. 

Can bacterial vaginosis come back after treatment?

Yes, bacterial vaginosis can recur, sometimes within a few weeks. If this happens, see your nurse or doctor for further treatment. This may include a longer course of antibiotics and checking for any other infections.

To prevent bacterial vaginosis recurring you could consider temporarily avoiding sexual contact or, if you have sex with a new partner, make sure to use protection.