Bacterial Vaginosis

bacterial vaginosis

What is bacterial vaginosis and what are the symptoms?

Bacterial vaginosis (BV) is a common condition of the vagina caused by an overgrowth of various bacteria (germs). The main symptom of BV is a vaginal discharge. The discharge is often white-grey in color, and often has a fishy smell. The smell may be more noticeable during sex. The discharge tends to be heaviest just after a period, or after sex. The discharge does not usually cause itch or soreness around the vagina and vulva.

What causes bacterial vaginosis?

In BV, an overgrowth of various bacteria occurs in the vagina. Normally, there are various different types of harmless bacteria in the vagina. These bacteria help in the defense against harmful germs. In BV, there is a change in the balance as a result, certain bacteria multiply and thrive much more than usual.

BV is not caused by poor hygiene. In fact, excessive washing of the vagina may alter the normal balance of bacteria in the vagina, which may make BV more likely to develop.

Who gets bacterial vaginosis and how common is it?

Any woman can be affected by BV. BV is more common in women who have an intrauterine contraceptive device (IUCD). It may also be more common in women who smoke. Hormone changes during your menstrual cycle as well as genetics may also play a part.

Is bacterial vaginosis a sexually transmitted disease?

No, BV can affect any woman, including those who do not have (or who have never had) sex. However, BV is more common amongst sexually active women than amongst non-sexually active women. Sexual partners of women with BV do not need any treatment.

How is bacterial vaginosis diagnosed?

The typical discharge and its characteristic fishy smell make BV likely. However, there are some tests available that can help to confirm the diagnosis. Also, if you are pregnant, it is important to make an accurate diagnosis if you have vaginal discharge so that any infection can be treated effectively.

Testing the acid level of your vagina

The discharge of BV has a typical pH level (acid/alkaline balance) compared to other causes of discharge. The overgrowth of the bacteria of BV causes the pH to change in the vagina so that it becomes more alkaline, i.e. the pH rises.

Taking a sample (a swab)

To confirm the diagnosis, your doctor or nurse may also suggest that a sample (a swab) of your discharge be taken from your vagina and sent to the laboratory for testing.

What are the possible complications with bacterial vaginosis?

BV and pregnancy

If you have untreated BV during pregnancy, you have an increased risk of developing early labor, miscarriage, having a low birth-weight baby or developing an infection of the uterus (womb) after childbirth.

BV and surgery

If you have untreated BV, the chance of developing an infection of the uterus is higher following certain operations (such as termination of pregnancy or a vaginal hysterectomy).

BV and other infections

If you have untreated BV, you may have an increased risk of developing HIV infection if you have sex with someone who is infected with HIV. There is also some evidence that women with untreated BV may be at an increased risk of developing pelvic inflammatory disease (PID).

What is the treatment for bacterial vaginosis?

Not treating is an option for some women with mild symptoms.

BV is often asymptomatic (it causes no symptoms), or the symptoms are mild. Also, there is a good chance that BV will gradually clear without treatment. Any disruption in the balance of vaginal bacteria may be corrected naturally, with time.

However, if you are pregnant and you are found to have BV but have no symptoms, you may still be advised to take antibiotic treatment. All pregnant women who have symptoms due to BV should be offered treatment.

If you are found to have BV and are undergoing a termination of pregnancy, treatment with antibiotics may also be advised even if you are asymptomatic. This is because there is a risk of BV causing a more serious infection of the uterus (womb) or pelvis after the procedure if it is not treated.


A course of metronidazole tablets is the common treatment. Metronidazole is an antibiotic. It clears BV in most cases.

The usual dose is 400-500 mg twice a day for 5-7 days. A single dose of 2 grams is an alternative, although this may be less effective and may cause more side-effects. (Note: this single dose is not recommended if you are pregnant.) Some people feel sick or 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.

Do not drink any alcohol while taking metronidazole, and for at least 48 hours after stopping treatment. The interaction with alcohol can cause vomiting and other problems such as flushing and an increased pulse rate.

Breast-feeding: metronidazole can get into breast milk but will not harm your baby. However, oral metronidazole is not recommended and instead you should use vaginal metronidazole or clindamycin.

Alternative antibiotic treatments

Metronidazole vaginal gel or clindamycin vaginal cream placed inside the vagina can be used if you prefer this type of treatment, or have unpleasant side-effects with metronidazole tablets.

Do I need a test of cure?

Women who are not pregnant

After treatment, you do not need any further tests (such as swab tests) to ensure that BV has cleared (a test of cure) provided that your symptoms have gone.

Treating recurrences

If you have a recurrence of symptoms and did not have any swab tests taken initially, your doctor or nurse may suggest that they take swab tests now. This is to confirm that it is BV causing your symptoms.BV may recur if you did not complete your course of antibiotics.

If you have an intrauterine contraceptive device (IUCD) and have recurrent BV, your doctor or nurse may suggest that they remove your IUCD to see if this helps to improve your symptoms.

How to prevent further episodes of bacterial vaginosis?

  • Do not push water into your vagina to clean it (douching). The vagina needs no specific cleaning.
  • Do not add bath oils, antiseptics, scented soaps, perfumed bubble bath, shampoos, etc, to bath water.
  • Do not use strong detergents to wash your underwear.
  • Do not wash around your vagina and vulva too often. Once a day is usually enough

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