Bacterial vaginosis keeps coming back — and treating the male partner cut recurrence
Most women have a recurrence within a year of standard treatment. A 2025 trial stopped early once treating a woman alone proved inferior to treating her and her male partner together.
| Group | Value (%) |
|---|---|
| Woman + male partner treated | 35 |
| Woman treated alone (standard care) | 63 |
Bacterial vaginosis is the most common vaginal condition in reproductive-aged women, affecting about one in three, and its defining frustration is that it comes back: most women have a recurrence within a year of standard antibiotic treatment [s1] [s2]. A 2025 trial offers the strongest evidence yet for why — and found that treating a woman's male partner alongside her substantially reduced the return of the condition [s1].
Why it recurs
The recurrence problem is not new or marginal. In a cohort study that followed 130 women after the recommended treatment of oral metronidazole, 58% had a recurrence of bacterial vaginosis by 12 months (95% confidence interval 49% to 66%), and 69% had a recurrence of abnormal vaginal flora over the same period [s2]. The authors' conclusion was that current recommended treatment "is not preventing the recurrence" in the majority of women [s2].
That study also found a pattern that pointed toward a cause. Recurrence was significantly associated with having a regular sexual partner throughout the study and with having female sexual partners, while hormonal contraception was associated with lower recurrence [s2]. Those associations led the researchers to argue for "a possible role for sexual transmission" in recurrent bacterial vaginosis — a hypothesis that, for years, standard care did not act on, because partners were not treated [s2].
The trial that tested it
The 2025 study, published in the New England Journal of Medicine, put that hypothesis to a randomised test [s1]. It enrolled couples in which a woman had bacterial vaginosis and was in a monogamous relationship with a male partner. In the intervention group, the woman received first-line recommended treatment and her male partner received a combined course of oral and topical antimicrobials — metronidazole tablets plus a clindamycin cream applied to penile skin, both twice daily for seven days [s1]. In the control group, the woman received the same first-line treatment and her partner received nothing, which is standard care [s1].
The trial did not run to its planned end. Its data and safety monitoring board stopped it after 150 couples had completed the 12-week follow-up, because treating the woman alone had proven inferior to treating both [s1]. In the analysis, bacterial vaginosis recurred in 24 of 69 women (35%) in the partner-treatment group and in 43 of 68 women (63%) in the control group [s1]. Expressed as rates, that was 1.6 recurrences per person-year (95% CI 1.1 to 2.4) with partner treatment versus 4.2 (95% CI 3.2 to 5.7) without — an absolute difference of 2.6 fewer recurrences per person-year (95% CI 1.2 to 4.0 fewer; P<0.001) [s1]. Adverse events reported by the treated men were nausea, headache and a metallic taste [s1].
How much this changes
For a condition long framed as something a woman simply keeps getting, the finding reframes recurrent bacterial vaginosis as, at least in part, a shared one between partners — which is why treating only one of them left recurrence so high. That is a meaningful shift in the evidence.
The limits are worth stating precisely. The trial was open-label, so participants knew which group they were in, and it enrolled monogamous heterosexual couples — it does not speak to women without a regular male partner, or to same-sex partnerships, where the transmission dynamics the earlier cohort hinted at may differ [s1] [s2]. Its outcome window was 12 weeks, not years [s1]. And the specific drugs, doses and combinations used are treatment decisions for clinicians, not something to be assembled from a news summary.
The liftable answer: bacterial vaginosis recurs in most women after standard treatment, the reason appears to be partly sexual transmission, and a 2025 trial showed that adding treatment for the male partner cut recurrence enough that the trial was halted early.
This article is informational and is not medical advice. Diagnosis and treatment of bacterial vaginosis, for a woman or a partner, should be handled by a qualified clinician.
Sources
- Male-Partner Treatment to Prevent Recurrence of Bacterial Vaginosis — New England Journal of Medicine , March 1, 2025
- High recurrence rates of bacterial vaginosis over the course of 12 months after oral metronidazole therapy and factors associated with recurrence — The Journal of Infectious Diseases , April 26, 2006
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