Bacterial vaginosis explained

What bacterial vaginosis is

The healthy vagina contains a community of bacteria dominated by lactobacilli, which keep the environment slightly acidic and discourage other microbes. In bacterial vaginosis this balance shifts: lactobacilli fall and a mixture of other bacteria overgrows, making the vagina less acidic. This change produces the symptoms of BV. It is very common and is not a sign of poor hygiene; in fact, over-washing can make it more likely. BV is not considered a sexually transmitted infection, and it can occur in people who are not sexually active, but it is more common with a new sexual partner or more partners. Understanding it as an imbalance, rather than an infection caught from someone, helps make sense of why it behaves as it does.

Recognising the symptoms

The hallmark of BV is a change in vaginal discharge: it often becomes thin, greyish-white, and watery, with a distinctive fishy smell that can be more noticeable after sex or around a period. Many women have no symptoms at all, and BV is sometimes found incidentally. Importantly, BV does not usually cause soreness, itching, or irritation. That helps distinguish it from thrush, a fungal infection, which typically causes itching and a thicker, white, cottage-cheese-like discharge without a strong smell. Because these conditions are treated differently, telling them apart matters. If there is pain when passing urine, pain during sex, bleeding between periods, or lower tummy pain, that points away from simple BV and towards another cause that needs assessment.

How it is diagnosed

BV is often recognised from the typical history and the characteristic discharge and smell. A clinician, a sexual health clinic, or sometimes a pharmacist may confirm it by checking the acidity of the vaginal fluid and, where needed, examining a sample under a microscope or sending a swab to the laboratory. Testing the vaginal pH is helpful because BV raises it above the normal acidic range. Where symptoms are not clear-cut, or where a sexually transmitted infection is possible, testing helps rule out other causes such as thrush, trichomoniasis, chlamydia, or gonorrhoea. Self-diagnosis can be unreliable, so if symptoms are new, recurrent, or uncertain, it is sensible to get a proper assessment rather than assuming which condition is present.

Treatment and self-care

BV that is not causing symptoms may not need treatment and can settle by itself. When treatment is needed, it usually involves antibiotics prescribed as tablets or as a vaginal gel or cream, obtained from a GP or sexual health clinic. Symptoms often improve within a few days, though it is important to complete the course. Some vaginal treatments and gels that restore acidity are available from pharmacies and can help milder cases; a pharmacist can advise. Helpful self-care includes avoiding perfumed soaps, vaginal deodorants, douching, and strong detergents, all of which disturb the natural balance. Washing gently with water or a plain emollient and avoiding over-washing supports the vagina's own defences. Alcohol is generally best avoided with certain antibiotics used for BV.

Recurrence, pregnancy, and when to see a clinician

BV commonly comes back, and some women have repeated episodes; in that situation a clinician can discuss longer or maintenance treatment approaches and review triggers. See a GP or sexual health clinic if this is your first episode, if symptoms do not settle with treatment, if they keep returning, or if you are unsure whether it is BV, thrush, or a sexually transmitted infection. Treating BV is particularly important in pregnancy, because untreated BV has been linked to complications such as premature birth, so pregnant women with symptoms should seek advice promptly. Also seek review if you have pelvic pain, fever, abnormal bleeding, or discharge with other worrying features, as these suggest a different or more serious problem needing assessment.