Patient information from BMJ

Bacterial vaginosis

Last published:Mar 13, 2020

If you have bacterial vaginosis, you have an infection in your vagina. It's very common but usually not serious. Having treatment with antibiotics can help to clear it.

You can use our information to talk to your doctor about which treatments are right for you.

What is bacterial vaginosis?

Usually, there are a lot of 'friendly' bacteria called Lactobacillus in your vagina. They help keep your vagina healthy. If you have bacterial vaginosis, the balance of bacteria in your vagina is disrupted. The 'friendly' bacteria are replaced with other bacteria called anaerobes.

Doctors aren't sure what causes bacterial vaginosis. The infection is not usually passed on during sex. But you are more likely to get it if you have a new sexual partner, or if you have a lot of sexual partners.

Bacterial vaginosis is not usually harmful and sometimes clears up on its own without treatment. However, it may increase your chance of serious problems if you are pregnant.

These problems include:

• having a miscarriage (losing your baby)

• having your baby early (before the 37th week of pregnancy)

• having a small (low birth weight) baby

• getting an infection in your womb (uterus) during or after your pregnancy

• being more likely to get some sexually transmitted infections (STIs), such as gonorrhoea, chlamydia, and HIV, if you are exposed to them.

What are the symptoms?

You might have a thin grey or white discharge from your vagina. It can have a fishy smell. These symptoms may be more noticeable after sex.

If your doctor thinks that you might have bacterial vaginosis, he or she will take a sample of fluid from your vagina. Your doctor might do some simple tests on the fluid there and then, or send it to a laboratory for testing.

What treatments work?

Bacterial vaginosis is treated with antibiotics. Antibiotics are drugs that kill bacteria. They help to get rid of the infection in most women.

If you are not pregnant

Your doctor will probably prescribe antibiotics if your bacterial vaginosis is causing symptoms. You can take antibiotics as tablets that you swallow, or as a gel, a cream, or capsules (called ovules) that you put in your vagina.

If the infection doesn't go away or if it keeps coming back, your doctor may recommend using an antibiotic gel twice a week for four to six months.

You can get side effects from antibiotics, including feeling nauseous and having thrush (a yeast infection) in your vagina.

If you take antibiotics called metronidazole or tinidazole you should not drink alcohol, because it can make you very ill, with symptoms such as redness in the face, headaches, trouble breathing, nausea, and vomiting.

You should also avoid alcohol 24 hours after having your last dose of metronidazole and 72 hours after finishing treatment with tinidazole. This will allow the medicine to fully leave your body.

Some antibiotic cream and ovules are oil based. This means that they may weaken latex condoms and diaphragms. This can happen for up to five days after you've used these treatments.

Ask your doctor or pharmacist if the products you are using are oil based, and read the information leaflet that comes with them. You should use non-latex contraception if you are using oil-based creams and ovules.

If you are pregnant

If you are pregnant and have symptoms of bacterial vaginosis, treatment with the right antibiotics is safe. Your doctor will probably prescribe metronidazole or clindamycin.

Should my partner be treated too?

Experts don't think that bacterial vaginosis is usually passed on during sex. So treating your partner with antibiotics isn't necessary to help you get rid of the infection, or to reduce your chances of getting it again. But your doctor may recommend not having sex while you're being treated for the infection.

What will happen to me?

In some women, bacterial vaginosis clears up without any treatment. But other women have a hard time getting rid of the infection.

Even after treatment, about one third of women with this condition get it again. To help reduce the chance of another infection, doctors often recommend avoiding vaginal douching (where you force water or another solution into your vagina to rinse it out). Avoiding strong soaps or bubble baths might also help.

Women with bacterial vaginosis sometimes also have infections that are passed on during sex. So your doctor may recommend having tests for gonorrhoea, chlamydia, syphilis, and HIV.