Can BV mean STD?

Officially, no. The NHS does not classify bacterial vaginosis as a sexually transmitted infection: it is caused by an imbalance of bacteria already living in the vagina, not by an organism caught from someone else, although sexual activity can trigger it or pass it on.¹ But this is one of the more unsettled questions in women's health right now, and research published in the last few years has made the picture more complicated, not less. Here's where things actually stand.

Is BV classed as an STI?

The standard position, from the NHS, is clear: BV is not classed as an STI. It's caused by an imbalance of bacteria that are already living in the vagina, rather than an organism passed from one person to another the way chlamydia or gonorrhoea are. That's the official line, and it's still what you'll be told at a GP or sexual health clinic.¹

That said, it isn't the whole story. Sex is measurably involved: across 43 studies, a new or additional male partner raised the risk of BV 1.6-fold, any female partner 2.0-fold, and condom use lowered it (relative risk 0.8).² In 2025 a trial in the New England Journal of Medicine gave the male partners of women with BV a week of oral antibiotics plus an antibiotic cream, and recurrence fell from 63% to 35%, which is the kind of result expected if BV-associated bacteria pass between partners.³ Some specialists argue that BV has the epidemiological profile of a sexually transmissible infection and should be reclassified. So the practical answer is that the science is actively shifting, even though the NHS still describes BV as not classed as an STI.¹

So can a partner give you BV?

In practice, yes, bacteria can be exchanged during sex in a way that disrupts your vaginal balance, even though BV isn't "caught" in the same way as a classic STI. The NHS is direct about this: sexual activity can pass BV on, and if your partner is a woman or has a vagina they may need treatment too.¹ In a study of 326 women who have sex with women, a quarter had BV, in 58 monogamous couples 95% shared the same BV status, and BV was more common in women who did not always clean an insertive sex toy before use.⁴

Male partners are a different story, since men don't develop BV themselves. Historically this meant male partners weren't treated at all, but the 2025 trial has started to change that advice for couples dealing with recurrent BV. We've gone into that specific research, along with the fuller picture on risk factors and recurrence, in Who Is Most Likely To Get BV? and Why do I keep getting BV?

Is BV a sign my partner has been unfaithful?

Not necessarily, and it's worth being careful with this assumption. BV can develop for reasons that have nothing to do with a new sexual contact, including a period, douching, perfumed products, a copper coil, smoking or simply a naturally lower level of protective bacteria.¹ It's true that BV can follow exposure to a new partner's bacteria, but it also follows sex with the same long-term partner, and a diagnosis on its own isn't evidence of anything beyond what it says on the test: a bacterial imbalance. We've covered the full list of everyday triggers in What Is The Main Cause Of BV?

What gets mistaken for BV?

Because BV's symptoms overlap with several other conditions, misdiagnosis (in both directions) is common enough that it's always worth getting a proper swab test (how BV is tested) rather than self-diagnosing. Is it thrush, BV or something else? has the full decision table; the short version:

• Thrush (yeast infection): thrush usually leaves the vaginal pH normal while BV raises it, but both cause discharge and irritation, and it's easy to confuse the two. Thrush discharge is typically thicker and white, without the fishy odour, and an anti-thrush cream does nothing for BV (or vice versa).
• Trichomoniasis: an actual STI caused by a parasite, trichomoniasis can cause a similar thin, unusual discharge and odour to BV, which makes clinical testing essential to tell them apart.
• Chlamydia: chlamydia is often symptomless, like BV, and the two can occur together often enough that a chlamydia test is usually recommended alongside a BV diagnosis. We've covered the specific link between the two in Can BV Cause A Positive Chlamydia Test?

Pelvic pain, fever, or bleeding between periods or after sex are not BV symptoms: see a GP or sexual health clinic, or call NHS 111, rather than wait.

Why the classification actually matters

This isn't just an academic debate. Whether BV is treated as an STI affects whether partners get tested and treated, whether protection is recommended during treatment, and how seriously recurrent cases get investigated. Whatever happens to the classification, the practical approach is the same either way: get a proper diagnosis rather than guessing, and if BV keeps coming back, raise the partner question directly with a GP or sexual health clinic rather than assuming there's nothing more to look into. A urinary tract infection is not an STI either, though sex is one of its triggers; why UTIs keep coming back has its recurrence plan.

If you're dealing with BV that won't stay away, we've covered what that can mean long-term in What does untreated BV lead to?

Frequently asked questions

Is BV considered an STD now?

Not officially. The NHS still classes BV as an imbalance rather than an STI.¹ The 2025 partner-treatment trial has strengthened the case of specialists who want it reclassified, but the NHS still describes BV as not classed as an STI.^{1, 3}

Is my boyfriend cheating if I get BV?

A BV diagnosis is not evidence of that. BV follows periods, douching, a copper coil and sex with the same long-term partner (1.9-fold higher recurrence in a 450-woman trial) as readily as a new partner; nothing in a swab result can tell you who your partner has slept with.^{1, 5}

Should my partner be tested or treated?

A partner who is a woman or has a vagina may need treatment, the NHS says. For a male partner, ask at a sexual health clinic: the 2025 trial's week of oral antibiotics plus cream cut recurrence from 63% to 35%, though the NHS page on BV mentions treatment only for a partner who is a woman or has a vagina.^{1, 3} With any new partner, an STI test for both of you is sensible regardless.

Sources

1. NHS. Bacterial vaginosis. nhs.uk/conditions/bacterial-vaginosis.
2. Fethers KA, et al. Sexual risk factors and bacterial vaginosis: a systematic review and meta-analysis. Clinical Infectious Diseases, 2008. PubMed 18947329.
3. Vodstrcil LA, et al. Male-partner treatment and recurrence of bacterial vaginosis. New England Journal of Medicine, 2025. PubMed 40043236.
4. Marrazzo JM, et al. Characterization of vaginal flora and bacterial vaginosis in women who have sex with women. Journal of Infectious Diseases, 2002. PubMed 12001048.
5. Bradshaw CS, et al. Recurrence of bacterial vaginosis is significantly associated with posttreatment sexual activities and hormonal contraceptive use. Clinical Infectious Diseases, 2013. PubMed 23243173.