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 It is still one of the more unsettled questions in women's health. Across 43 studies, a new or additional male partner raised the risk of BV 1.6-fold and a female partner 2.0-fold, and in 2025 a trial that gave the male partners of women with BV a week of antibiotics cut recurrence from 63% to 35%.^{2, 3} This page sets out what the NHS says, what those studies measured, why a diagnosis is not evidence that anyone cheated, and what gets mistaken for BV.

Evidence at a glance

• Classification: the NHS says BV "is not classed as an STI, but it can be triggered by sex", on a page reviewed on 19 June 2026.¹
• Sexual risk: a pooled analysis of 43 observational studies; relative risk 1.6 for a new or additional male partner, 2.0 for any female partner, 0.8 for condom use.²
• Largest trial: 164 Australian couples, 2025, publicly funded; a week of antibiotics for the male partner; recurrence within 12 weeks 35% against 63%.³
• Not known: how long a man carries BV-associated bacteria, and whether a first episode can ever be traced to a partner.

Sources checked on 29 October 2026.

Is BV classed as an STI?

The standard position, from the NHS, is clear: BV is not classed as an STI. It is 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 is the official line, and it is still what you will be told at a GP surgery or sexual health clinic.¹

It is not 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); the authors concluded that BV has "an epidemiological profile similar to that of established sexually transmitted infections".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 Specialists now describe those results as new evidence on sexual transmission, so the science is shifting even though the NHS still describes BV as not classed as an STI.^{1, 4}

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 is not "caught" in the same way as a classic STI. The NHS is direct about this: "You can pass it to a woman, or to anyone with a vagina, during sex", 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.⁵

Male partners are a different story, since men do not develop BV themselves, and until the 2025 trial they were not treated at all. The fuller picture on risk factors and recurrence is in Who Is Most Likely To Get BV? and Why do I keep getting BV?

Why did I get BV if I'm not sexually active?

Because sex is a trigger, not the cause. The NHS lists being sexually active among the things that make BV more likely, then adds that "women who have not had sex can also get bacterial vaginosis".¹ The other triggers it names are a change of partner, an IUD, perfumed products in or around the vagina, douches, vaginal deodorants, antiseptic in the bath and smoking, and a clinic can "help identify if something is triggering your bacterial vaginosis, such as sex or your period".¹ In the study of 326 women above, BV was common among women who did not douche and had no new partner.⁵ A first episode in a woman who is not having sex is the ordinary form of the condition, not a mystery.

Is BV a sign my partner has been unfaithful?

Not necessarily, and it is 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, an IUD, smoking or a naturally lower level of protective bacteria.¹ It is true that BV can follow exposure to a new partner's bacteria, but it also follows sex with the same long-term partner: in a 450-woman Australian trial, having the same partner before and after treatment nearly doubled recurrence (adjusted hazard ratio 1.9), and so did inconsistent condom use (1.9).⁶ A diagnosis on its own is not evidence of anything beyond what it says on the test: a bacterial imbalance. We have covered the everyday triggers in What Is The Main Cause Of BV?

Can men get BV, and how long can a man carry the bacteria?

Men do not get BV: it is a condition of the vagina, and the NHS describes passing it only to a woman or to anyone with a vagina.¹ What men can do is carry the bacteria associated with it. The 2025 trial was built on that idea: the male partner took antibiotic tablets and applied an antibiotic cream to the skin of the penis for seven days, and the women whose partners were treated had fewer recurrences.³ How long a man carries those bacteria has not been measured. A man with symptoms of his own, such as discharge or pain when peeing, has something else and needs a sexual health clinic.

What gets mistaken for BV?

BV's symptoms overlap with several other conditions, so a swab test (how BV is tested) beats self-diagnosis. Is it thrush, BV or something else? has the full decision table; the short version:

• Thrush (yeast infection): thrush leaves the vaginal pH normal while BV raises it; thrush discharge is thicker and white, without the fishy odour, and an anti-thrush cream does nothing for BV.
• Trichomoniasis: an STI caused by a parasite. The NHS describes "a yellow-green discharge from your vagina that may smell like fish", starting 5 to 28 days after infection, which is close enough to BV that only a test tells them apart.⁷
• Chlamydia: often symptomless, like BV, and a chlamydia test is usually offered alongside a BV diagnosis; see 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

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 are investigated. Recurrence after standard treatment exceeds 50% over three to six months, so the partner question is live for a lot of women.⁴ Whatever happens to the classification, get a proper diagnosis rather than guessing, use condoms through treatment (inconsistent use went with 1.9-fold higher recurrence), and if BV keeps coming back raise the partner question at a GP surgery or sexual health clinic.⁶ What does untreated BV lead to? covers the long-term picture; a urinary tract infection is not an STI either, and why UTIs keep coming back has its recurrence plan.

What we don't know

• Which organism, if any, is the cause. The 2025 primer says "the exact aetiologic agent of BV is unknown", which is why BV cannot be classed as an STI the way chlamydia is.⁴
• How long a man carries BV-associated bacteria, and whether treating a partner helps beyond the 12 weeks the 2025 trial measured.³
• Whether UK guidance will follow the trial; the NHS page mentions treatment only for a partner who is a woman or has a vagina.¹

Frequently asked questions

Is BV considered an STD now?

Not officially. The 2025 partner-treatment trial has strengthened the case of specialists who want it reclassified, but the NHS page, reviewed in June 2026, 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, an IUD 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, 6}

Can BV turn into an STD?

No. BV does not become chlamydia, gonorrhoea or anything else. The NHS does say BV "increases your risk of getting an STI", probably because it makes the vagina less acidic, which is one more reason to test for both with a new partner.¹

Should my partner be tested or treated?

A partner who is a woman or has a vagina may need treatment, the NHS says, so tell them. For a male partner with recurrent BV, ask at a sexual health clinic whether treating him is an option: the 2025 trial's week of antibiotics cut recurrence from 63% to 35%, though the NHS page does not yet mention it.^{1, 3} With any new partner, an STI test for both of you is sensible regardless.

Sources

1. NHS. Bacterial vaginosis. Page last reviewed 19 June 2026. 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. Pooled analysis of 43 observational studies; non-commercial research support. PubMed 18947329.
3. Vodstrcil LA, et al. Male-partner treatment and recurrence of bacterial vaginosis. New England Journal of Medicine, 2025. Open-label randomised trial, 164 couples, 12 weeks; recurrence 35% against 63%; funded by the National Health and Medical Research Council of Australia. PubMed 40043236.
4. Bradshaw CS, et al. Bacterial vaginosis. Nature Reviews Disease Primers, 2025. Expert review; lead author declares research grants from Australian public funders and advisory work for a diagnostics company. PubMed 40537474.
5. Marrazzo JM, et al. Characterization of vaginal flora and bacterial vaginosis in women who have sex with women. Journal of Infectious Diseases, 2002. Observational study, 326 women, 58 monogamous couples; US public funding. PubMed 12001048.
6. Bradshaw CS, et al. Recurrence of bacterial vaginosis is significantly associated with posttreatment sexual activities and hormonal contraceptive use. Clinical Infectious Diseases, 2013. Analysis within a randomised trial, 450 women, 6 months; non-commercial research support. PubMed 23243173.
7. NHS. Trichomoniasis. Page last reviewed 16 July 2025. nhs.uk/conditions/trichomoniasis.

General information, not medical advice. BV is diagnosed and treated by a GP or sexual health clinic; see one about any unusual discharge, pelvic pain or bleeding between periods or after sex.

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