Sexual Health Advice - Patient Information Leaflets
Bacterial Vaginosis
Bacterial vaginosis (BV) is a common cause of vaginal discharge. The discharge is not usually itchy or sore. It is not a sexually transmitted infection. Symptoms are often mild, and it may clear without treatment. A course of antibiotics usually clears bacterial vaginosis.
What is bacterial vaginosis?
Bacterial vaginosis is a very common condition of the vagina. It is caused by an overgrowth of various bacteria (germs). At least 1 in 10 women will have bacterial vaginosis at some time in their life. The cause of bacterial vaginosis is not really understood, but it is likely to occur when the pH (acid/alkali balance) of the vagina is altered in women. Men do NOT get bacterial vaginosis.
Up to half of women have no symptoms, so you may not know you have bacterial vaginosis.
How do you get bacterial vaginosis?
Bacterial vaginosis can occur when the pH in the vagina is altered and becomes more alkali.
This can happen if you:
• Douche (push water into the vagina to clean it)
• Use scented soaps / perfumed bubble bath
• Use strong detergents to wash your underwear
• Smoke
Other triggers may include genetic factors, hormonal changes during the menstrual cycle and semen in the vagina after sex without a condom.
What are the symptoms of bacterial vaginosis?
The main symptom of bacterial vaginosis is vaginal discharge. Bacterial vaginosis is the most common cause of vaginal discharge. The discharge is often thin and watery, a white-grey colour and often a strong fishy smell. The discharge tends to be heaviest just after a period or after having sex. The smell may also be noticeable during/after sex.
Up to half of women with bacterial vaginosis do not have any symptoms. In these women bacterial vaginosis is often a chance finding when vaginal swabs are taken for other reasons.
The discharge of bacterial vaginosis does not usually cause itching or soreness around the vulva and vagina unlike thrush.
How is bacterial vaginosis diagnosed?
The discharge of bacterial vaginosis has a typical acid level pH compared to other causes of discharge. Therefore, the pH of the vagina may be measured using a sample of vaginal discharge wiped on a piece of specially treated paper. A specimen of discharge may be added to a chemical called potassium hydroxide. If you have bacterial vaginosis, this produced a characteristic fishy smell.
A sample (swab) of the discharge may be sent for testing. Large numbers of various bacteria that occur with bacterial vaginosis are seen under the microscope.
Sometimes bacterial vaginosis may be noted on a routine cervical smear test, but you only need treatment if you have problems with discharge.
What are the possible complications with bacterial vaginosis?
Pregnancy
If you have untreated bacterial vaginosis during pregnancy, you have an increased risk of developing some complications of pregnancy. For example it can cause early labour, miscarriage, and infection of the uterus (womb) after childbirth. (There is however no evidence that bacterial vaginosis will affect your chances of getting pregnant).
Surgery
If you have untreated bacterial vaginosis, the chance of developing an infection of the uterus is higher following certain operations e.g. following a termination of pregnancy or a vaginal hysterectomy. Antibiotics given before various operations usually prevent these infections.
HIV
If you have untreated bacterial vaginosis, you have an increased risk of developing HIV infection if you have sex with someone who is infected with HIV.
What is the treatment for bacterial vaginosis?
Oral antibiotics – a course of metronidazole usually clears bacterial vaginosis in about 7 – 8 in 10 cases.
• The usual dose is 400 mg twice a day for seven days. A single dose of 2 grams is an alternative, although this may be less effective and may cause more side-effects.
• Some people feel sick, and may vomit when they take metronidazole. This is less likely to occur if you take the tablets straight after food. A metallic taste is also a common side-effect.
• Alcohol should be avoided while taking metronidazole, and for at least 48 hours after stopping treatment. The interaction with alcohol can cause vomiting and other problems.
• Breastfeeding: metronidazole can get into breast milk, but is not thought to affect breastfed babies. However, to play safe, the standard lower dose 7-day course is preferred.
Antibiotic cream / gel
Metronidazole vaginal gel or clindamycin vaginal cream placed inside the vagina can be used if you prefer a topical treatment, or have unpleasant side-effects with metronidazole tablets. Some vaginal creams can cause weakening of latex condoms, diaphragms and caps. Therefore, during treatment and for five days after treatment with vaginal creams, do not rely on condoms to protect against pregnancy and sexually transmitted diseases.
Not treating is an option if you are not pregnant
For many women bacterial vaginosis goes away without treatment, as the balance of bacteria in the vagina may correct itself. However, if you are pregnant you will usually be advised to take antibiotic treatment to prevent the increased risks during pregnancy if you have bacterial vaginosis (described above).
Treating recurrences
Bacterial vaginosis recurs within three months in about half of women who have been successfully treated. If it does recur, a repeat course of antibiotics will usually be successful. A small number of women have repeated episodes of bacterial vaginosis, and need repeated courses of antibiotics.
How can I prevent further episodes of bacterial vaginosis?
Most episodes of bacterial vaginosis occur for no apparent reason, and cannot be prevented. However, the following are thought to help prevent some episodes of bacterial vaginosis. The logic behind these tips is to try not to upset the normal pH balance in the vagina.
• To avoid cleaning the vagina with water (douching)
• Not adding bath oils, detergents, bubble bath to bath water
NB: There are no treatments that you can buy without a prescription and there is no evidence that complementary therapies can treat bacterial vaginosis.
