What Is Bacterial Vaginosis (BV)? Signs, Causes and Treatment That Actually Works

Written by Dr. Simon Khela MBChB MRCGP, GMC Registered Doctor

Last reviewed: 03-07-2026

An unusual discharge. A smell that wasn’t there last week. A nagging feeling that something’s off, even though nothing actually hurts. If that sounds familiar, you’re probably dealing with bacterial vaginosis — the most common vaginal condition in women of reproductive age, and one of the most misunderstood.

BV isn’t an STI, it isn’t caused by poor hygiene, and it isn’t rare  around 1 in 3 women experience it at some point. What trips people up isn’t the condition itself but the noise around it: half-right advice from forums, home remedies that don’t work, and confusion over whether it’s even worth treating. This guide sorts through all of that  what BV actually is, the signs worth paying attention to, why it happens, how it’s diagnosed, and which treatments genuinely clear it up.

What is bacterial vaginosis?

Bacterial vaginosis (BV) is caused by an imbalance in the bacteria that naturally live in the vagina. In a healthy vaginal environment, Lactobacillus bacteria dominate, keeping things mildly acidic and well-protected against overgrowth from other organisms. When that balance shifts, other bacteria  most commonly Gardnerella vaginalis  multiply and take over, producing the thin discharge and characteristic odour associated with BV.

It’s not a sexually transmitted infection, though sexual activity is one of several factors that can influence your risk. Women who’ve never been sexually active can develop BV, and it occurs more frequently in women who have sex with women — both facts that point to the bacterial imbalance itself as the underlying cause, not what most people assume.

Who gets bacterial vaginosis, and how common is it?

BV is genuinely common  estimates suggest it affects around a third of women of reproductive age at some point, making it more common than thrush. It’s most frequently seen in women aged 15–44, though it can occur at any age once periods have started. Because roughly half of all cases produce no noticeable symptoms, a huge number of episodes go entirely undiagnosed, which is part of why BV has such a reputation for “coming out of nowhere.”

Symptoms of bacterial vaginosis you shouldn’t ignore

BV symptoms are often subtle enough to dismiss  which is exactly why so many cases go untreated for months. Here’s what to actually pay attention to:

• A thin, watery discharge that’s white, grey, or slightly green  noticeably different from your usual
• A strong, fishy odour, often more obvious after sex or during your period
• Mild itching or irritation, though this is less pronounced than with thrush
• A change in discharge volume or consistency that doesn’t match your normal cycle pattern

What tends to get missed: roughly half of BV cases cause no symptoms at all. That means a “normal-feeling” cycle doesn’t rule it out, particularly if you’re due a private cervical smear test, an IUD fitting, or another gynaecological procedure — untreated BV can complicate these.

A separate set of signs deserves faster action rather than a wait-and-see approach:

• Symptoms alongside pelvic pain or fever this points away from BV and towards something needing urgent review
• New symptoms during pregnancy treat promptly rather than waiting for your next scheduled appointment
• Symptoms that return repeatedly within weeks of finishing treatment
• Discharge that’s thick and clumpy rather than thin and watery  this is more consistent with thrush and needs different treatment entirely

Guessing which category you’re in from a symptom list is exactly where things go wrong. A swab test settles it in days.

BV vs thrush vs an STI

If your symptoms don’t cleanly match one column, that’s normal plenty of women experience BV and thrush at different points in the same cycle, or confuse early signs of a genuine STI for BV. A chlamydia test or gonorrhoea test alongside a BV swab rules out the STI possibility properly rather than leaving you guessing.

What causes bacterial vaginosis?

BV develops when something disrupts the vagina’s protective bacterial balance. Recognised risk factors include:

• Douching or washing inside the vagina with soap, shower gel, or scented products
• New or multiple sexual partners
• Not using condoms
• Smoking
• Having an IUD (coil) fitted
• Hormonal changes, including around your period, or during perimenopause and menopause

None of these guarantees BV, and plenty of women with none of these risk factors get it anyway. The vaginal microbiome is genuinely sensitive, and sometimes it shifts for reasons medicine doesn’t fully explain yet. If you’re noticing a pattern of BV alongside other hormonal changes, it’s worth discussing with a GP through our menopause clinic if that timing lines up for you.

Is bacterial vaginosis an STI?

No — BV is not classified as a sexually transmitted infection. It’s caused by a natural bacterial imbalance rather than an organism passed between partners, which is why it can occur in women who aren’t sexually active. That said, sexual activity is one of several factors that can influence your risk, and having BV can slightly increase your vulnerability to picking up an actual STI if you’re exposed to one — which is one reason it’s worth treating rather than ignoring, and why a full sexual health screen is often the more thorough option if you’re due a check-up anyway.

How is bacterial vaginosis diagnosed?

BV is usually diagnosed with a simple vaginal swab, checked against a set of criteria that look at:

• Vaginal pH — BV typically raises it above the normal acidic range
• The presence of “clue cells” vaginal cells coated in bacteria, visible under a microscope
• A characteristic odour when the sample is tested with a mild alkaline solution (the “whiff test”)

It’s a quick, low-discomfort test, and results are usually available within a few days. This matters because BV, thrush, and early STI symptoms can look similar enough that self-diagnosing from a symptom checklist isn’t reliable — a proper test tells you what you’re actually treating, rather than guessing and buying the wrong product from a pharmacy shelf.

Treatment options that actually work

The reliable route is a short course of prescribed antibiotics:

• Metronidazole — oral tablets or a vaginal gel, typically for 5–7 days. If you’re prescribed the oral tablets, avoid alcohol during treatment and for 48 hours afterwards, as the combination can cause an unpleasant reaction.
• Clindamycin cream — an alternative for those who can’t take metronidazole, applied internally for around a week

Most people see improvement within a few days, but finishing the full course matters — stopping early because symptoms have faded is one of the most common reasons BV comes straight back.

What doesn’t work (despite what forums suggest)

Worth knowing before you try them: yoghurt applied vaginally, tea tree oil, apple cider vinegar douches, and probiotic supplements alone are not proven to clear an active BV infection. Some may play a supporting role in maintaining balance afterwards, but none reliably treats BV on their own  and douching in particular can make things worse by disrupting the bacterial balance even further.

What helps alongside treatment

• Wash the genital area with water only no soap, no scented products, no “feminine hygiene” washes
• Avoid douching altogether, both during and after treatment
• Avoid smoking, which is linked to higher recurrence rates
• Change out of damp gym or swimwear promptly, since prolonged moisture can disturb the natural bacterial balance

Does bacterial vaginosis go away on its own?

Sometimes, if symptoms are mild. But it can also persist for months untreated, and going untreated during pregnancy or before a gynaecological procedure carries added risk. If you have symptoms, testing and treating is the more reliable path than waiting it out and hoping.

Why does bacterial vaginosis keep coming back?

Recurrence within 12 months affects roughly half of women treated for BV it’s not a sign you did anything wrong. The vaginal microbiome simply takes time to re-establish its protective bacteria after an episode, and each course of antibiotics resets the environment rather than permanently “fixing” it. If BV keeps returning, it’s worth discussing longer-term management with a GP  sometimes this means a longer or repeated course of treatment, sometimes it means looking at contributing factors like an IUD or a new medication, rather than simply repeating the same short course indefinitely.

Bacterial vaginosis and pregnancy

BV is common in pregnancy and is treated with the same antibiotics, which are considered safe under medical supervision. Treatment tends to be more proactive here because untreated BV has been linked to a higher risk of preterm birth and low birth weight. If you’re pregnant and notice symptoms, get it checked promptly rather than waiting for your next scheduled appointment  this is one condition where “wait and see” genuinely isn’t the safer option.

Possible complications of untreated BV

Most cases of BV resolve without lasting issues once treated, but leaving it unaddressed particularly if it’s recurrent can carry some added risk:

• A higher chance of acquiring other infections, including STIs, if exposed
• Complications around procedures such as IUD fitting, smear tests, or minor gynaecological surgery
• Increased risk of preterm birth if untreated during pregnancy

None of this is a reason to panic if you have BV it’s a very treatable condition  but it is a reason to treat it properly rather than repeatedly self-managing with unproven remedies.

When to see a doctor

Book a test if you notice discharge, odour, or comfort changes that aren’t your normal especially if:

• Symptoms haven’t improved after a course of treatment
• BV keeps recurring
• You’re pregnant
• You’re due an IUD fitting, smear test, or other gynaecological procedure
• Symptoms come with pelvic pain or fever

Why choose private testing and treatment

At Private Medical Clinic, we offer same-day private testing and treatment for bacterial vaginosis, with results turned around quickly and no NHS waiting list to sit through. Every consultation is with a GMC-registered GP, carried out discreetly, and if you’d rather not discuss symptoms in person first, our online GP consultations let you start the conversation from home. Clinics are available across Birmingham, London, Newcastle, Leicester, Oxford, Derby, Sutton Coldfield, and Bournemouth & Dorset , Manchester and Cambridge. You can check current pricing on our fees page, and if you have any questions before booking, our FAQs cover most of what people ask.

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