Bacterial vaginosis

What is it?          

Bacterial vaginosis (BV) is not a sexually transmitted infection but can develop after you've had sex.

How do I get it?               

Bacterial vaginosis (BV) is the most common cause of unusual vaginal discharge. One in three people with a vagina get it at some time. People with a penis don’t get bacterial vaginosis.
People who have bacterial vaginosis can have:

  • less normal vaginal bacteria (lactobacilli)
  • an overgrowth of other types of bacteria in the vagina
  • a change in pH (acid/alkaline balance) of the vagina with the vagina becoming more alkaline.

Bacterial vaginosis is more common if you:

  • use medicated or perfumed soaps, bubble bath or shower gel
  • put antiseptic liquids in the bath
  • douche or use vaginal deodorant
  • use strong detergents to wash your underwear
  • smoke.

Hormonal changes during the menstrual cycle, receiving oral sex, semen in the vagina after sex without a condom, an intrauterine contraceptive device (IUD) and genetic factors may also play a part.

Signs and Symptoms     

Around half of people with bacterial vaginosis won’t have any signs and symptoms at all, or may not be aware of them. You might notice a change in your usual vaginal discharge. This may increase, become thin and watery, change to a white/grey colour and develop a strong, unpleasant, fishy smell, especially after sex. Bacterial vaginosis isn’t usually associated with soreness, itching or irritation.


A doctor or nurse may examine inside of your vagina to look at any vaginal discharge and to collect a sample from the vaginal walls using a swab. A swab looks like a cotton bud, but is smaller and rounded. It sometimes has a small plastic loop on the end rather than a cotton tip. It only takes a few seconds to wipe over the area and isn’t usually painful, though it may be uncomfortable for a moment. The pH (alkaline/acid balance) of the vagina may be measured by wiping a sample of vaginal discharge over a piece of specially treated paper.


  • Treatment for bacterial vaginosis is simple and involves taking antibiotic tablets. There are several different antibiotics that can be used. These are taken either as a single dose or a longer course (up to one week).
  • You may be given a cream or gel instead. You’ll need to use this in the vagina for 5–7 days.
  • The doctor or nurse will advise you how to use the treatment. If you’re given the antibiotic metronidazole, either as tablets or a vaginal gel, you’ll be advised not to drink alcohol during the treatment and for 48 hours afterward. This is because it reacts with alcohol and can make you feel very unwell.
  • Some creams can weaken latex condoms, diaphragms and caps. Polyurethane types can be safely used. Ask the doctor or nurse for advice.
  • Tell the doctor, nurse or pharmacist if you’re pregnant, think you might be, or you’re breastfeeding. This can affect the type of treatment you’re given.

Further Guidance: Bacterial vaginosis (BV)