BV keeps coming back. Your partner might be why
Bacterial vaginosis affects about 1 in 3 women, and more than half of those treated for it are back with the same thing within a year. The evidence increasingly points at the same explanation whoever your partner is: BV-associated bacteria are shared between partners, and treating one person leaves the other carrying them.
The short version: BV happens when the Lactobacillus that should dominate your vaginal microbiome get outnumbered by other bacteria, mainly Gardnerella and Atopobium. Standard treatment clears it, and then it very often comes back, and for years nobody could explain why. A randomised trial published in the New England Journal of Medicine in March 2025 tested whether treating a male partner at the same time made a difference. It did, by enough that the trial was stopped early. Among women with female partners the transmission evidence is arguably stronger still, though nobody has run the equivalent treatment trial. That doesn't mean the guidelines have changed, and it's worth understanding why not.
In short
- BV affects roughly 1 in 3 women of reproductive age, and up to 60% of those treated have it back within 12 months.
- The StepUp trial found recurrence dropped from 63% to 35% when a male partner was treated too.
- In female couples, BV concordance runs as high as 95%, and having a partner with BV is one of the strongest risk factors there is.
- The trial was stopped early because treating the woman alone was clearly the worse option.
- But a pooled analysis of all 6 trials on this shows no overall effect, and guidelines haven't changed. There's a good reason for the gap.
- Testing both of you is the sensible first step, and a partner can test at home without going anywhere.
No doctor's referral, no appointment. A self-collected swab, at a branch in Observatory, Parktown North or Hillcrest, or from a home kit posted anywhere in South Africa. Results in 5 to 7 working days.
What is BV?
A healthy vaginal microbiome is dominated by Lactobacillus species, which keep the environment acidic and make it hard for anything else to establish itself. BV is what happens when that balance tips and other bacteria take over, mainly Gardnerella vaginalis and Atopobium vaginae, along with Mobiluncus, Megasphaera and Prevotella.
People often call it a BV infection, though strictly it's an imbalance rather than an infection caught from outside. The symptoms are a thin greyish discharge, a fishy smell that's often worse after sex, and irritation. Plenty of women have no symptoms at all, which is part of why it goes unrecognised for so long.
It isn't classed as a sexually transmitted infection, and that framing has shaped how it's treated for decades. But sex has always been the clearest risk factor, a new partner raises your risk, and the bacteria involved turn up on the penile skin and in the urine of male partners of women who have it. That was the loose thread somebody eventually pulled.
Treatment works in the short term. What it doesn't do is stop it returning, and up to 60% of women have it back inside a year. That's the part that wears people down, and it isn't a failure of willpower or hygiene. Something keeps reintroducing the bacteria.
What are the symptoms of BV?
The classic three are a thin, greyish or off-white discharge, a fishy smell that gets noticeably worse after sex or during your period, and mild irritation or burning. Some women get all three. Plenty get none at all, which is one reason BV goes unrecognised for so long.
The smell is the symptom people search for most, and it's the one that distinguishes BV from most other things. It's caused by amines released by the overgrown bacteria, and it becomes stronger when it meets semen, which is alkaline. If the smell is what sent you looking, that's a genuinely useful clue.
BV or a yeast infection?
They're often confused and they're treated completely differently, so getting it wrong is a common reason nothing improves. The short version:
| Bacterial vaginosis | Yeast infection (thrush) | |
|---|---|---|
| Discharge | Thin, greyish or off-white | Thick, white, often described as like cottage cheese |
| Smell | Fishy, worse after sex | Usually little or no smell |
| Itching | Mild or absent | Usually the main complaint |
| Caused by | Overgrowth of bacteria, mainly Gardnerella | Overgrowth of a yeast, usually Candida |
| Treated with | Antibacterial treatment | Antifungal treatment |
Trichomonas causes a similar picture again and is a genuine sexually transmitted infection. That's three different causes of much the same symptom, which is why a test that names the organism beats guessing at a pharmacy counter.
What causes BV?
Nobody can point at a single cause, but the risk factors are consistent and well documented.
Sex, and particularly a new partner. This is the strongest and most consistent association, and it's the thread the 2025 trial pulled on.
Douching or washing inside the vagina. It strips out the Lactobacillus you need and doesn't remove what you don't. The vagina cleans itself; soap and water on the outside is all that's wanted.
Smoking, which is associated with lower Lactobacillus levels.
An intrauterine device, in some women.
What doesn't cause it: poor hygiene. That's worth saying directly, because a lot of women arrive convinced it's their fault, and washing more makes it worse rather than better.
On boric acid and probiotics. Both come up constantly and neither is a substitute for finding out what you actually have. Vaginal probiotics aim to restore the Lactobacillus that BV depletes, and the idea is sound, but the evidence on whether over-the-counter products achieve it is mixed. Boric acid suppositories are used by some clinicians for recurrent cases and are not something to start on your own; boric acid is toxic if swallowed and must never be taken by mouth. Talk to a doctor before either.
Why does BV keep coming back?
If you've had BV more than twice you'll recognise this without needing it explained. It's the loop on the left of the diagram below: symptoms, a course of treatment, a few good weeks, and then it's back, along with the cost and the frustration and the growing sense that you're doing something wrong.
The right-hand side is the interesting bit, and it came out of the interviews the researchers did alongside the trial. The men who took part didn't describe it as a burden. They described it as a week of inconvenience that was obviously worth it, and several said the thing that got them on board was simply understanding the science.
Is BV an STI? What the 2025 trial found
The StepUp trial ran at the Melbourne Sexual Health Centre and was published in the New England Journal of Medicine in March 2025. It enrolled monogamous heterosexual couples where the woman had symptomatic BV. Everyone's female partner got standard first-line treatment. In one group the male partner got a 7-day course of oral and topical antimicrobial treatment as well. In the other, he got nothing, which is standard care everywhere.
Woman treated alone
63%
had BV again within 12 weeks. Recurrence rate 4.2 per person-year.
Both partners treated
35%
had BV again within 12 weeks. Recurrence rate 1.6 per person-year.
Vodstrcil et al., New England Journal of Medicine, March 2025. The trial was stopped early by its data safety monitoring board because treating the woman alone was clearly inferior.
Time to recurrence stretched from an average of 54 days to 74. The hazard ratio was 0.37, which means the risk was cut by roughly two thirds. And recurrence was lowest of all where the male partner had taken every dose, which is exactly the pattern you'd expect if reinfection is the mechanism.
It wasn't effortless. Just under half the men reported some side effect, most commonly nausea, headache, a metallic taste or skin irritation, and where men didn't complete the course it was usually the topical part they gave up on rather than the tablets.
What if my partner is a woman?
Then the transmission evidence is, if anything, better than it is for male partners. It's just a different kind of evidence, and it's worth understanding the difference.
BV can be diagnosed in both people in a female couple, which male partners don't allow, so researchers have been able to look at it directly. What they find is striking. Across cross-sectional studies, BV prevalence among women who have sex with women runs between 25% and 52%, higher than in women who only have male partners. In one study of monogamous couples, vaginal smears were concordant in 55 of 58 pairs, which is 95%, and both partners had BV in 28% of couples.
A 24-month cohort study found that a new sexual partner nearly tripled the risk of developing BV, and having a partner with BV symptoms raised it around fourfold. A systematic review found that simply having a female partner doubles the risk. The authors of that review concluded the pattern supports BV being sexually transmitted between women.
And the finding that cuts the other way is the encouraging one. In that same cohort, women enrolled alongside a partner who did not have BV had a much lower risk of developing it themselves, and the pair tended to hold a normal, stable vaginal flora between them over two years. So this isn't only about passing something unwanted back and forth. A healthy microbiome appears to be shared too.
Two practical things follow. The risk factors reported in female couples aren't identical to the heterosexual ones: sharing sex toys without cleaning them between uses, receptive oral sex and a higher number of female partners all came up, while douching and hormonal contraception, both associated with BV in women with male partners, did not.
And the honest limitation: there is no partner-treatment trial in female couples. StepUp enrolled monogamous heterosexual couples only, so the 63% to 35% figure below is specific to male partners. What the evidence in female couples supports is testing both of you, and taking a concordant result to a doctor. It doesn't yet tell you what treating both of you achieves, because nobody has measured it.
So why haven't the guidelines changed?
Because one trial, however good, sits inside a literature. And the rest of that literature doesn't agree with it.
A systematic review published in 2025 pooled 6 randomised trials covering 953 couples and found no significant reduction in BV recurrence from treating male partners overall. The CDC's STI guidelines still don't recommend it.
Here's the part that makes sense of the contradiction, though. When the reviewers removed StepUp from the pool, the statistical inconsistency between the remaining trials disappeared, and StepUp was the only one of the 6 that gave men both an oral and a topical treatment. Every earlier trial used tablets alone.
So the most likely reading isn't that StepUp is wrong. It's that treating men with tablets alone doesn't work, treating the skin as well does, and the older trials were testing the wrong thing. That's a hypothesis rather than a settled fact, and it needs replicating in other populations, particularly where circumcision rates are high and topical treatment may behave differently.
What that means for you, practically. Partner treatment isn't standard care in South Africa and your doctor may not have come across the trial. That's a reasonable position for them to hold, not a failing. If your BV keeps coming back, the useful thing you can do is arrive with information rather than a request: what you've both been tested for, what keeps recurring, and the fact that there's now a New England Journal trial on it. The decision is theirs to make with you.
How do I even bring this up with my partner?
This is the part that stops most people. The trial interviews are useful here because the researchers asked participants what actually changed their minds, and while those interviews were with male partners, the reasoning travels.
Lead with the science, not the blame
The participants who agreed said understanding why mattered more than anything else. BV isn't something anyone did wrong and it isn't an accusation. These are bacteria that get shared between bodies, which is a very different conversation from the one people are dreading.
Be clear about what's actually involved
A week. That's the whole ask. Participants in the trial described it as a week of inconvenience, and several said it made them feel useful rather than blamed, because for the first time there was something they could do.
Make it easy
The thing that got in the way most often was logistics rather than willingness. A home test kit that arrives in unbranded packaging and gets couriered back removes most of the friction, because nobody has to book time off or sit in a waiting room.
Where can I get a BV test in South Africa?
Testing comes before any of this, because recurrent symptoms aren't always BV and treating the wrong thing is a common reason nothing improves.
You don't need a doctor's referral if you're paying cash. Epicentre is a walk-in laboratory with branches in Observatory in Cape Town, Parktown North in Johannesburg and Hillcrest in Durban, open Monday to Friday from 08:30 to 16:00, and you can book your own panel. If you'd rather not come in at all, home kits post anywhere in South Africa in unbranded packaging with a pre-paid courier return, so a partner in another city can test on the same day you do.
BV and Vaginal Microbiome Screen
R1,609A 17-target PCR panel of the vaginal microbiome, so you see the balance rather than a yes or no. It covers Gardnerella vaginalis, Atopobium vaginae, BVAB2, both Mobiluncus species, Megasphaera 1 and 2 and Prevotella bivia, alongside the 4 Lactobacillus species that should be dominant.
That last part matters. Knowing which Lactobacillus you're short of is more useful than knowing you have BV, because it tells you what the microbiome is missing rather than only what has taken over.
Sample: self-collected swab, no speculum.
Results: 5 to 7 working days.
For a partner with a vagina
R1,609The same BV and Vaginal Microbiome Screen. Testing both of you is the point: concordance between female partners runs as high as 95%, so a result from one person tells you very little about the pair until you have both.
Sample: self-collected swab, no speculum.
Results: 5 to 7 working days.
For a partner with a penis
R1,925A 17-target panel including Gardnerella vaginalis and Prevotella bivia, the BV-associated organisms found on penile skin, alongside the standard sexually transmitted infections. Self-collected swab and urine sample, at a branch or from a home kit in unbranded packaging.
Worth saying plainly: this is a test, not a treatment. It tells you both what's there. What happens next is a doctor's call.
Sample: self-collected swab and urine.
Results: 5 to 7 working days.
If you want the widest single panel for either of you, the Extra Large Sexual Health screen covers 34 targets at R3,305 and isn't sex-specific. A single Gardnerella test is R253 if you only want that one organism. Everything is on the sexual health page. Prices are 2026 cash rates including VAT and may change; in-store pricing applies.
What happens after the results
We're a laboratory. We test and we report, and we don't diagnose, prescribe or treat. Your PCR results come back as a plain-language report you can take to any doctor, and if you don't have one, we work with an independent doctor who consults online or in person and can take it from there. There's no obligation to use them.
Basically
If your BV keeps returning, you're not doing anything wrong and you're not unlucky. There's now good evidence that reinfection from an untreated partner is part of the picture, even though BV still isn't officially classed as an STI and the guidelines haven't caught up.
Test both of you first, so you know what you're actually dealing with. Then take the results to a doctor and have the conversation about partner treatment. A week of inconvenience shared between two people beats another course on your own in 4 months' time.
Stop guessing why it keeps coming back
A 17-target look at your vaginal microbiome, self-collected, no referral and no speculum. Home kits post nationwide in unbranded packaging.
Frequently Asked Questions
What is BV?
Bacterial vaginosis is an imbalance in the vaginal microbiome. The Lactobacillus species that normally dominate and keep the environment acidic get outnumbered by other bacteria, mainly Gardnerella vaginalis and Atopobium vaginae, along with Mobiluncus, Megasphaera and Prevotella. It affects about one in three women of reproductive age. It is not currently classed as a sexually transmitted infection, although sex is the strongest risk factor.
What are the symptoms of BV?
A thin greyish or off-white discharge, a fishy smell that is worse after sex or during a period, and mild irritation or burning. Many women have no symptoms at all. The smell is the most distinctive feature and is caused by amines released by the overgrown bacteria, which become stronger on contact with semen.
What does BV smell like?
A fishy odour, which typically becomes stronger after sex or around a period. It is caused by amines produced by the bacteria that overgrow in BV, and semen makes it more noticeable because it is alkaline. A yeast infection usually has little or no smell, which is one of the easiest ways to tell the two apart.
What is the difference between BV and a yeast infection?
BV produces a thin greyish discharge with a fishy smell and mild or no itching, and is caused by an overgrowth of bacteria. A yeast infection produces a thick white discharge, usually with little smell, and itching is normally the main complaint. It is caused by an overgrowth of a yeast, usually Candida. They need different treatments, so treating the wrong one is a common reason symptoms do not improve. Trichomonas causes a similar picture again and is a sexually transmitted infection.
What causes BV?
There is no single cause, but the risk factors are consistent: sex and particularly a new sexual partner, douching or washing inside the vagina, smoking, and in some women an intrauterine device. Poor hygiene does not cause BV. Washing more, or washing internally, makes it more likely rather than less, because it removes the Lactobacillus that keep the microbiome balanced.
Do probiotics or boric acid help with BV?
Neither is a substitute for finding out what you actually have. Vaginal probiotics aim to restore the Lactobacillus that BV depletes and the rationale is sound, but the evidence on whether over-the-counter products achieve it is mixed. Boric acid suppositories are used by some clinicians for recurrent cases and should not be started without medical advice; boric acid is toxic if swallowed and must never be taken by mouth.
Where can I get a BV test in South Africa?
Epicentre is a walk-in laboratory with branches in Observatory in Cape Town, Parktown North in Johannesburg and Hillcrest in Durban, open Monday to Friday from 08:30 to 16:00. No doctor's referral is needed if you are paying cash. The BV and Vaginal Microbiome Screen is R1,609 and covers 17 targets. Home kits post anywhere in South Africa in unbranded packaging with a pre-paid courier return, and results take 5 to 7 working days.
Is BV a sexually transmitted infection?
Not officially, and that's still the formal position. But sex is the clearest risk factor, a new partner raises your risk, and BV-associated bacteria are found on the penile skin and in the urine of male partners of women who have it. The 2025 StepUp trial, which found that treating male partners cut recurrence, has led a lot of clinicians to argue the classification needs revisiting. It hasn't been changed yet.
Why does my BV keep coming back?
Up to 60% of women treated for BV have it again within 12 months, and reinfection from an untreated partner appears to be part of the reason. Standard treatment clears the overgrowth but doesn't restore the Lactobacillus that keep it away, and if BV-associated bacteria are being reintroduced, the same thing happens again. Other things that raise the risk include a new partner, douching and smoking.
Should my partner be treated for BV?
That's a decision for a doctor, and it isn't standard care yet. The StepUp trial published in the New England Journal of Medicine in March 2025 found recurrence fell from 63% to 35% when male partners received a 7-day course of oral and topical treatment alongside the woman, and the trial was stopped early because treating the woman alone was clearly inferior. However, a pooled analysis of 6 trials found no overall effect, and CDC guidelines still don't recommend partner treatment. The likely explanation is that StepUp was the only trial to use both oral and topical treatment for men.
Can BV be passed between female partners?
The evidence suggests yes, and it is arguably stronger than the evidence for male partners because BV can be diagnosed in both people. Prevalence among women who have sex with women runs between 25% and 52%, higher than in women with only male partners. In one study of monogamous couples, vaginal smears were concordant in 55 of 58 pairs, or 95%. A cohort study found that having a partner with BV symptoms raised the risk of developing BV around fourfold, and a systematic review found that simply having a female partner doubles the risk. Encouragingly, the same cohort found that women whose partner did not have BV had a much lower risk themselves.
Should my female partner be tested for BV?
Testing both of you makes sense, because concordance between female partners is very high and a result from one person tells you little about the pair. Both partners can take the same BV and Vaginal Microbiome Screen at R1,609, which is a self-collected swab available as a home kit. What the evidence does not yet cover is treatment: the 2025 partner-treatment trial enrolled heterosexual couples only, so there is no equivalent trial showing what treating both partners in a female couple achieves.
Can my partner be tested for BV bacteria?
Yes. The BV-associated organisms, including Gardnerella vaginalis and Prevotella bivia, are on the 17-target Large Sexual Health panel for anyone with a penis, which costs R1,925 and comes with a home kit option. The sample is a self-collected swab plus urine, so nobody has to go anywhere, and results take 5 to 7 working days.
How much does a BV test cost in South Africa?
At Epicentre the BV and Vaginal Microbiome Screen is R1,609 and covers 17 targets, including the BV-associated bacteria and the 4 Lactobacillus species that should be dominant. A single Gardnerella test is R253 if that's all you want. The Cervical Large Sexual Health panel, which adds the sexually transmitted infections and HPV to the vaginal microbiome, is R1,925. No doctor's referral is needed and results take 5 to 7 working days.
Can I test for BV at home?
Yes. Home kits are available for the BV screen and for the partner panels, posted anywhere in South Africa in unbranded packaging with a pre-paid courier return. You collect the swab yourself, with no speculum and no examination, and results come back in 5 to 7 working days.
Is BV dangerous if I just leave it?
It's worth treating rather than ignoring. BV is associated with a higher risk of acquiring sexually transmitted infections, and in pregnancy it's linked to preterm birth and low birth weight. It's also linked to pelvic inflammatory disease and to complications after gynaecological procedures. None of that means a single episode is an emergency, but recurrent BV is a reason to see a doctor rather than to keep managing it yourself.
What these words mean
- Bacterial vaginosis (BV)
- An imbalance in the vaginal microbiome where Lactobacillus are outnumbered by other bacteria, mainly Gardnerella and Atopobium.
- Lactobacillus
- The bacteria that should dominate a healthy vaginal microbiome. They keep the environment acidic, which makes it hard for other organisms to establish.
- Gardnerella vaginalis
- The bacterium most consistently associated with BV. It's also found on the penile skin and in the urine of male partners of women who have BV.
- Recurrence
- BV returning after treatment has cleared it. Up to 60% of women experience it within 12 months.
- Partner treatment
- Treating a sexual partner at the same time as the person with symptoms, so that reinfection can't restart the cycle. Standard for several STIs; not yet standard for BV.
- PCR
- A laboratory method that copies an organism's genetic material until it can be identified, so many organisms can be detected and named from a single sample.
References
- Vodstrcil LA, Plummer EL, Fairley CK, et al., for the StepUp Team. Male-partner treatment to prevent recurrence of bacterial vaginosis. New England Journal of Medicine 2025;392(10):947-957. doi:10.1056/NEJMoa2405404
- The efficacy of male partner treatment to prevent recurrence of bacterial vaginosis: a systematic review with meta-analysis of randomised controlled trials. PMID 41780137
- Vodstrcil LA, Plummer EL, Doyle M, et al. Treating male partners of women with bacterial vaginosis (StepUp): a protocol for a randomised controlled trial. BMC Infectious Diseases 2020. Read it
- Marrazzo JM, Koutsky LA, Eschenbach DA, et al. Characterization of vaginal flora and bacterial vaginosis in women who have sex with women. PMID 12001048
- Vodstrcil LA, Walker SM, Hocking JS, et al. Incident bacterial vaginosis in women who have sex with women is associated with behaviors that suggest sexual transmission of BV. Clinical Infectious Diseases 2015;60(7):1042-1053. Read it
- Forcey DS, Vodstrcil LA, Hocking JS, et al. Factors associated with bacterial vaginosis among women who have sex with women: a systematic review. PLOS One 2015. Read it
- Plummer EL, et al. A prospective, open-label pilot study of concurrent male partner treatment for bacterial vaginosis. Read it
This article is general health information and not medical advice. Epicentre is a diagnostic laboratory: we test and we report, and we don't diagnose, prescribe or treat. Partner treatment for BV is not currently recommended in standard guidelines and any decision about treatment is one for your doctor. If you are pregnant and have symptoms of BV, please see a doctor promptly.
