Bacterial vaginosis (BV): symptoms, treatment and how to stop it coming back

The NHS lists two main symptoms: an unusual vaginal discharge that has a strong fishy smell, particularly after sex, and a change to the colour and consistency of the discharge, such as becoming greyish-white, thin and watery. It says BV does not usually cause any soreness or itching.

NICE Clinical Knowledge Summaries adds that when symptoms are present, BV is characterised by a fishy-smelling vaginal discharge, and that approximately 50% of women with BV are asymptomatic. Examination may show a thin, white, homogeneous discharge coating the walls of the vagina.

Not all unusual discharge is BV. The NHS says to check other causes of changes to your discharge if you are unsure.

The NHS says BV is usually treated with antibiotic tablets, gels or creams, prescribed by a GP or sexual health clinic. It says if your partner is a woman or has a vagina, they may also need treatment.

NICE CKS says non-pregnant women with asymptomatic BV do not usually require treatment. For symptomatic women, oral metronidazole is the treatment of choice, with intravaginal metronidazole gel or intravaginal clindamycin cream as alternative choices, and oral clindamycin and oral tinidazole as less preferred alternatives. It says that in women with characteristic symptoms, examination and further tests may be omitted and treatment started if there is a low risk of an STI, no other symptoms, it is the first episode, and the woman is not pregnant.

Your clinician will give the dose and length of course.

NICE CKS describes BV as an overgrowth of predominantly anaerobic organisms and a loss of lactobacilli, so that the vagina loses its normal acidity and its pH rises above 4.5. The NHS describes it as an imbalance of bacteria in the vagina.

NICE CKS says BV is the most common cause of abnormal vaginal discharge in women of childbearing age, though it may also be seen in peri or postmenopausal women.

The NHS says what causes the change in balance is not fully known. It lists things that make you more likely to get it. NICE CKS adds further contributing and protective factors.

• Being sexually active, although the NHS notes that women who have not had sex can also get BV.

• A change of partner.

• Having an IUD (contraceptive device); NICE CKS specifies copper intrauterine devices.

• Using perfumed products in or around the vagina, and douches, deodorants and vaginal washes.

• Smoking, and factors linked with an alkaline vaginal pH such as menstruation and semen (NICE CKS).

• Protective factors listed by NICE CKS: hormonal contraception, consistent condom use and a circumcised partner.

The NHS says BV is not classed as an STI, but sexual activity can trigger it or pass it on. You can pass it to a woman, or to anyone with a vagina, during sex. NICE CKS says BV is not an STI, but being sexually active or having concurrent STIs increases the risk of developing BV.

The NHS says BV increases your risk of getting an STI, possibly because it makes the vagina less acidic and reduces natural defences against infection. NICE CKS notes women with BV are at increased risk of acquiring STIs, including HIV.

There is no home treatment that replaces antibiotics, but the NHS lists things that can help relieve symptoms and prevent BV returning. Do not self-diagnose, because other conditions need different treatment.

• Use water and plain soap to wash the genital area.

• Have showers instead of baths.

• Do not use perfumed soaps, bubble bath, shampoo or shower gel in the bath.

• Do not use vaginal deodorants, washes or douches, or put antiseptic liquids in the bath.

• Do not use strong detergents to wash your underwear.

• Do not smoke.

The NHS says it is common for BV to come back, usually within a few months. If it comes back you will usually be given more antibiotics. If you keep getting it (more than 4 times in a year) you may be given an antibiotic gel that you put in your vagina, which you may need to use for a few months to help stop it coming back. A GP or sexual health clinic can help identify whether something is triggering your BV, such as sex or your period.

NICE CKS says that if symptoms persist or recur after initial treatment, the clinician should check that treatment was completed, reconsider the diagnosis, check continued exposure to contributing factors and make sure the current episode is adequately managed.

The NHS says that if you develop BV in pregnancy there is a small chance of complications, such as premature birth or miscarriage, but that it causes no problems in the majority of pregnancies. It says it is important to seek treatment if you are pregnant, and to speak to a GP or your midwife if your vaginal discharge changes. The NHS pregnancy guidance says to call your midwife if discharge smells unpleasant or strange, is green or yellow, or you feel itchy or sore, or have pain when you pee.

NICE CKS says routine screening for BV should not be offered to pregnant women. For symptomatic pregnant women, oral metronidazole is the treatment of choice, with intravaginal metronidazole gel or clindamycin cream as alternatives, and clindamycin cream not recommended in the first trimester.

The NHS says a GP or sexual health clinic will want to confirm it is BV and rule out an STI. You will be asked about your symptoms, and a doctor or nurse may look at your vagina. A cotton bud may be wiped over the discharge inside your vagina to test for BV and other infections.

NICE CKS says tests involve checking the pH of the vaginal discharge and/or sending a sample to the laboratory for microscopy. The NHS says many sexual health clinics offer a walk-in service and will often get test results quicker than GP surgeries.

The NHS says to see a GP or go to a sexual health clinic if you think you have BV. It says to get help from NHS 111 if your vaginal discharge changes colour, smell or texture, you produce more discharge than usual, you feel itchy or sore, you bleed between periods or after sex, you get pain when peeing or you have pelvic pain.

Pelvic pain or bleeding with discharge points away from simple BV and needs prompt assessment, as the NHS list of possible causes includes chlamydia and gonorrhoea when discharge comes with pelvic pain or bleeding.

On the NHS you can be seen by a GP or at a sexual health clinic, many of which offer walk-in services. Treatment is prescribed after assessment, and repeat or long-term gel treatment can be arranged for recurrent BV.

Private GPs and sexual health clinics offer similar testing and treatment. Ask whether the clinic tests for STIs at the same time, and what follow-up is offered if symptoms return.