Bacterial Vaginosis

BV develops when lactobacilli are depleted and the vaginal pH rises. Anything that disturbs that balance can trigger it.

• Douching or internal washing. A direct, well-established cause — it flushes out precisely the bacteria that protect you. Nothing should be washed inside the vagina, ever
• Soaps, shower gels, bubble baths and "feminine hygiene" products, including scented wipes and vaginal deodorants
• A new sexual partner, or multiple partners. BV is not classed as a sexually transmitted infection — women who have never had sex can get it — but sexual activity clearly influences the vaginal environment, and semen is alkaline
• Sex between women, where BV can be shared between partners, and treating both is sometimes appropriate
• The copper coil, which is associated with higher rates
• Smoking
• Periods, and the use of tampons
• Antibiotics, which disturb bacterial populations generally

Why it matters beyond the symptoms

BV is not merely a nuisance. It raises susceptibility to sexually transmitted infections including HIV, and in pregnancy it is associated with late miscarriage and preterm birth, which is why symptomatic BV in pregnancy is always treated.

In a woman with the classic picture — thin grey discharge, fishy smell worse after sex, no itch — BV can be diagnosed from the history and treated without testing, which suits a remote consultation well.

Where testing is used:

• Vaginal pH — BV raises the pH above 4.5. Simple, and part of the standard clinical criteria
• A high vaginal swab examined under the microscope shows the characteristic "clue cells" — vaginal cells coated in bacteria. This is the definitive test and is done in sexual health clinics
• STI screening where there is any risk of exposure, or where symptoms are atypical or persistent. Chlamydia, gonorrhoea and trichomonas all cause discharge and are regularly missed when BV is assumed

What else causes these symptoms

• Thrush — thick white discharge, itch, no smell. The opposite pattern
• Trichomonas — frothy yellow-green offensive discharge, often with soreness. This is sexually transmitted and needs partner treatment, so it matters to distinguish
• A retained tampon or condom — a very common cause of sudden foul-smelling discharge, and one that is resolved in seconds once identified. Always worth considering
• Cervical infection or inflammation
• Persistent offensive discharge that does not respond to treatment needs examination, including a look at the cervix

The rules that matter most

• Never douche or wash inside the vagina. Not with water, not with anything else. The vagina is self-cleaning, and internal washing is a direct cause of BV
• Stop using soap, shower gel, bubble bath, scented wipes and any "intimate" or "feminine hygiene" product. Plain water on the vulva — the outside — is all that is needed. If you want something, an emollient used as a soap substitute is fine
• No vaginal deodorants, perfumed products, or scented panty liners
• Cotton underwear; avoid heavily perfumed detergents and fabric conditioner on it
• Do not leave tampons in longer than recommended, and check nothing has been forgotten — a retained tampon is a common and instantly solvable cause
• Stop smoking, which is independently associated with BV

Reducing recurrence

• Condoms reduce recurrence for some women, by limiting alkaline semen exposure
• Consider whether a copper coil is a factor if BV became frequent after it was fitted
• Ask about suppressive treatment if you have three or more episodes a year, rather than treating each separately
• Ask about lactic acid gels as a maintenance measure

A word about the shame

The smell of BV causes considerable distress, and the instinct is almost always to wash more thoroughly and more often. That instinct makes it worse. This is a shift in bacterial populations, it happens to women who have never had sex, and it says nothing about cleanliness or behaviour. Nobody should feel awkward raising it.

Is BV a sexually transmitted infection?

No. Women who have never had sex can develop it, and it is a disturbance of your own bacterial balance rather than something passed on. That said, sexual activity does influence the vaginal environment, a new partner is a recognised trigger, and BV can be shared between female partners.

How do I tell it from thrush?

BV smells and does not itch. Thrush itches and does not smell. BV discharge is thin and grey-white; thrush is thick and white. They need completely different treatment — antifungals do nothing for BV — which is why buying the wrong thing at the pharmacy is such a common experience.

Does my partner need treating?

A male partner, no. This has been studied and treating him does not reduce your recurrence. For women with female partners, treating both may help.

Why does it keep coming back?

Because recurrence is genuinely common — over half of women have symptoms again within a year. The most useful things are removing the causes rather than repeating the cure: stop all washes and douching, consider whether a copper coil is contributing, and ask about suppressive gel treatment if it happens three or more times a year.

Can I drink while taking metronidazole?

No. Avoid alcohol during the course and for 48 hours afterwards. The combination causes flushing, severe nausea, vomiting and headache. Plan the course around this.

Am I not washing properly?

Almost certainly the opposite. Washing inside the vagina, and using soaps and intimate products on the vulva, is a leading cause of BV. The vagina cleans itself. Plain water on the outside is all that is required, and doing less genuinely helps more.

Does it need treating if I have no symptoms?

Generally not, outside pregnancy or before certain gynaecological procedures. Around half of women with BV have no symptoms and need nothing done.

Does it affect pregnancy?

Yes, which is why it is treated in pregnancy whenever it causes symptoms. BV is associated with late miscarriage and preterm birth. If you are pregnant and notice a change in discharge, that is worth raising rather than waiting.