Bacterial vaginosis (BV)

A fishy smell and a thinner, greyish-white discharge can be signs of bacterial vaginosis, usually shortened to BV. Some people notice the smell more after sex. Many people with BV have no symptoms at all.

BV involves an imbalance in the bacteria living in the vagina. The NHS does not class it as an STI, although sex can trigger it or pass it on. People who have never had sex can also develop BV.

What symptoms can and cannot tell you

The NHS says BV does not usually cause soreness or itching. Mention either symptom at your appointment, though neither can tell you the cause on its own. A clinician may need to check for BV and other infections, including STIs.

Describe the change in your own words: the smell, whether the discharge is thinner than before, and any discomfort. If you have already tried a vaginal product, bring its name. You can ask what the examination or sample is intended to check.

Why the bacterial balance changes

The exact cause is not fully understood. Douching and sex with a new partner or several partners are associated with BV. They may play a part, but cannot explain why a particular episode happened.

BV is not caught from toilet seats, bedding or swimming pools. Cleaning inside the vagina is also unhelpful: WHO identifies vaginal cleansing and douching as risk factors, along with inserting herbs or other products.

Avoid vaginal deodorants, washes and douches, and keep perfumed products out of bathwater. These are among the NHS suggestions for easing symptoms and preventing recurrence. Avoid washing inside the vagina even if the smell is stronger.

Checking and treating an episode

A GP, doctor or sexual health clinician will ask about symptoms and may examine the vagina. They may take a sample of discharge with a cotton swab to check for BV and other infections. A change in discharge is a reason to ask for assessment.

Treatment usually involves prescribed antibiotics, supplied as tablets, vaginal gel or cream. Your clinician can advise which form is suitable. Follow the prescribed instructions even if the discharge or smell settles, and ask your pharmacist or doctor about anything unclear.

BV commonly returns after treatment. A GP or sexual health clinic can discuss another treatment plan and possible triggers, including sex or periods. Bring the dates of previous episodes and the names of treatments you have tried.

When a partner may need treatment

Advice has changed recently. ACOG’s newer US guidance advises considering treatment at the same time for male sexual partners of adults with recurrent BV that causes symptoms.

The published advice differs. CDC’s older public information still says male partners do not need treatment. NHS information says a partner who is a woman or has a vagina may also need treatment. Ask your clinician how the newer evidence applies to your situation, particularly when symptoms keep returning.

You could ask: “Would treatment for a partner be relevant here?”, “What are the benefits and uncertainties?” and “What follow-up do we each need?” Ask the clinician to plan treatment for each of you; do not try to combine separate prescriptions into a shared plan.

Pregnancy and getting help

Contact your GP or midwife in the UK, or your doctor or midwife in the US and elsewhere, if vaginal discharge changes during pregnancy. BV is associated with pregnancy complications, including premature birth, although the NHS says it causes no problems in the majority of pregnancies.

Go to A&E now (UK), or an emergency department (US and elsewhere), for severe or worsening pelvic pain, or pelvic pain with faintness or heavy vaginal bleeding.

Contact an urgent GP service or NHS 111 today (UK), or your doctor or urgent care service (US and elsewhere), if discharge changes come with pelvic or lower tummy pain.

Outside pregnancy, book a GP or sexual health appointment in the UK, or a doctor or sexual health appointment elsewhere, if you think you have BV or symptoms return. BV is also associated with a higher risk of acquiring other STIs, so ask whether testing would be useful.