If you get bacterial vaginosis (BV) again and again, this one's for you.
New research suggests that for a lot of people, BV keeps coming back because it's being passed back and forth between partners. The way BV has usually been treated, with only the person who has symptoms getting medication, may be missing half the picture.
This doesn't mean you've done anything wrong. It means the advice may need to catch up.
A quick note on language: BV can affect anyone with a vagina, whatever their gender or who they have sex with. Where studies only included women, we say so. Everywhere else we use "people with vaginas" and "partners".
What is bacterial vaginosis (BV)?
BV is one of the most common vaginal conditions out there. It happens when the balance of bacteria in the vagina shifts. A healthy vagina is mostly home to friendly bacteria called lactobacilli, which keep things slightly acidic. In BV, those friendly bacteria drop and other bacteria, such as Gardnerella, multiply.
It isn't a sign of being unclean, and washing more won't fix it. In fact, over-washing can make it worse.
BV symptoms
Many people with BV have no symptoms at all. When symptoms do show up, they can include:
- Thin white or grey discharge
- A strong fishy smell, often more noticeable after sex or during your period
- Itching, soreness or burning around the vulva or vagina
- Burning when you wee
These symptoms overlap with thrush and some STIs, so it's worth getting tested rather than guessing. You can find a clinic near you in our sexual health services directory.
Why does BV keep coming back?
Recurring BV is incredibly common and incredibly frustrating. Reasons can include a vaginal balance that's slow to recover after antibiotics, things like douching or scented products, and, according to this new research, being re-exposed to BV-linked bacteria by a regular partner.
That last one is what makes this research such a big deal.
The announcement: treating both partners worked far better
A 2025 trial in Australia followed 164 monogamous couples where the woman had BV. Couples were split into two groups:
- Group one: only the woman was treated
- Group two: the woman was treated, and her male partner took an oral antibiotic and used an antibiotic cream on his penis
The results were so clear that the trial was stopped early. Within 12 weeks, 63% of women treated alone got BV again. When both partners were treated, that fell to 35%.
The researchers said reinfection from a regular sexual partner is a significant driver of BV coming back, and that treating BV can be a shared responsibility.
Wait, so is BV an STI now?
Not officially, and experts are split.
Some say these results are strong evidence that BV-linked bacteria are sexually transmitted, and note that we already treat partners for infections like chlamydia and gonorrhoea to stop them ping-ponging back and forth.
Others say it's too soon to reclassify BV. It can happen in people who've never had sex, so sex can't be the whole story. A good way to think about it is that BV is sexually associated: sex can spread the bacteria and trigger it, but it isn't the only cause.
UK and international guidance hasn't changed yet, so partner treatment isn't standard care. This is something to raise with your clinician, not something to start on your own.
What about same-sex couples and partners with vulvas?
This is a big gap, so let's be clear about it. The trial only included heterosexual couples, so it can't tell us whether partner treatment works for same-sex partners or for anyone with a vulva partner. The treatment tested (an oral antibiotic plus a cream for the penis) was designed for partners with penises.
What we do know is that BV is very common in people with vulvas who have sex with other people with vulvas, and the research that exists points towards sexual transmission being part of the picture:
- A small study of 36 women who have sex with women found that around 4 in 10 developed BV within 90 days, and new BV was linked to recent sex, including sex with a woman and sharing fingers or toys between partners
- The authors argued this is consistent with BV-linked bacteria being passed between partners, but the study was small and couldn't prove it
So the honest answer is: it plausibly spreads between partners with vulvas, but we don't yet know the best way to treat both of you to stop it coming back. The Melbourne team behind the trial is now looking for LGBTQIA+ couples for partner treatment research, which is a good sign that answers are coming.
In the meantime, it's worth knowing that BV can pass between people with vulvas, and chatting to your partner and clinician if yours keeps returning. Our LGBTQ+ sex, relationships and health guides cover more on looking after your sexual health.
BV, trans and non-binary people
There's very little research on BV in trans and non-binary people, so we can't say much with confidence. What we can say is that the advice above applies to anyone with a vagina, and anyone who has sex with someone with a vagina can carry BV-linked bacteria. If you're trans or non-binary and your BV keeps coming back, it's worth finding a clinic that's inclusive and affirming. Our sexual health services directory is a good place to start, and our trans+ sexual health and relationships guides have more.
What else the study didn't cover
- It didn't cover people with multiple partners
- It didn't include same-sex couples or people with partners who aren't male
- Most participants were from the Western Pacific and Europe, and BV rates vary between communities
What this means for you
If your BV keeps coming back, you're not doing anything wrong. Here's what can help:
- Get it properly diagnosed. Your GP or local sexual health clinic can test you, and it's free on the NHS.
- Ask about your partner. Guidance hasn't fully caught up yet, but it's a fair thing to raise, especially if you have a regular partner and BV keeps returning.
- Talk to your partner. This isn't about blame. It's bacteria being shared, and looking after each other's sexual health is part of having sex.
- Clean your toys and wash hands between partners or between body parts. If you share toys or fingers, this is a sensible habit.
- Go easy on your vagina. Skip douching and perfumed products. Your vagina cleans itself.
How is BV treated?
BV is usually treated with a short course of antibiotics, either as tablets or as a gel or cream used in the vagina. A GP or sexual health clinic can prescribe these. You'll usually feel better within a few days, but finish the full course even if your symptoms disappear.
At the moment, standard care treats only the person with BV. Treating partners isn't routine yet, but this research is the reason clinicians are starting to talk about it.
The bottom line
BV isn't officially an STI, but the idea that sex has nothing to do with it is looking out of date. If you're stuck in a BV loop, you deserve answers, not shame. Have the chat with your clinician and with your partner.
BV and partners: frequently asked questions
Is BV an STI?
Not officially. BV isn't classed as an STI because it can happen in people who've never had sex. But sex clearly plays a part, and new research suggests BV-linked bacteria can be passed between partners.
Can you get BV from a partner?
It looks that way. In a trial of 164 couples, treating both partners cut BV coming back from 63% to 35%, which suggests reinfection from a partner is a big driver of recurrence.
Can people with penises get BV?
Partners with penises can carry BV-linked bacteria, including on the skin of the penis and in the urethra, but they usually have no symptoms. That's why partner treatment is being studied.
Can BV pass between two people with vulvas?
Probably. BV is common in people with vulvas who have sex with each other, and small studies link new BV to recent sex with a partner. We don't yet know the best way to treat both partners, as the main trial only included heterosexual couples.
Can I get BV if I've never had sex?
Yes, though it's rare. That's one of the reasons BV isn't classed as an STI.
Should my partner be treated for BV?
It isn't standard care yet. If your BV keeps coming back, ask your GP or sexual health clinic whether partner treatment makes sense for you. Don't take or use antibiotics that haven't been prescribed.
Does BV go away on its own?
Sometimes, but not always. If you have symptoms, get checked. If you're pregnant, see a clinician promptly, as BV in pregnancy can be linked to complications.
Is BV the same as thrush?
No. Thrush is a yeast infection and usually causes thick, white discharge and itching. BV is a bacterial imbalance and tends to cause thin discharge and a fishy smell. They need different treatments, so get a proper diagnosis.
Do condoms help prevent BV?
Some evidence suggests condoms can lower the chance of BV coming back. Cleaning toys and washing hands between partners or body parts is also sensible. Condoms aren't foolproof for every infection, so read can you still pass on STIs if you wear a condom?
How can I stop BV coming back?
Get it properly diagnosed and treated, avoid douching and perfumed products, talk to your partner and clinician about whether partner treatment is an option, and see a clinician if it keeps returning.
When should I see a doctor about BV?
See a GP or sexual health clinic if you have unusual discharge or smell, if symptoms don't clear after treatment, if BV keeps coming back, or if you're pregnant.
Looking for support? Find a service near you in our sexual health services directory.
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