Can Men Get Bacterial Vaginosis?
A person without a vagina cannot develop bacterial vaginosis (BV) itself. BV is a change in the vaginal microbiota in which Lactobacillus bacteria decrease and a mixture of other bacteria becomes more abundant. A male partner can, however, carry BV-associated bacteria on the penis without having symptoms.
These bacteria can be shared between ongoing sexual partners. That does not make BV a conventional infection caused by one identifiable pathogen, and a BV diagnosis does not establish that either partner has had sex outside the relationship.
Why Treating a Male Partner May Reduce BV Recurrence
Treating an ongoing male partner aims to reduce the exchange of BV-associated bacteria while the partner with symptomatic BV is also being treated. The goal is to lower the chance of recurrence, not to cure a male disease called BV. It also does not mean that every recurrence comes from a partner.
The type of treatment matters to the evidence. Earlier studies of treating male partners, including a trial using oral metronidazole alone, did not show an overall reduction in BV recurrence. A newer trial found a benefit when male partners used oral medication and a topical antibiotic on the penis while their partners received BV treatment. That finding supports considering concurrent treatment in the partnerships studied, but it does not promise that BV will not return.
Who May Be Considered for Partner Treatment
Current New York State guidance supports offering treatment to an ongoing male partner of a person diagnosed with symptomatic BV. The strongest direct evidence comes from a trial involving monogamous couples consisting of premenopausal cisgender women with symptomatic BV and cisgender male partners. Partner treatment is a recurrence-prevention option to discuss with a clinician, rather than something every partner automatically needs.
There is no clinical test available to identify BV-associated bacteria on male genitalia. An asymptomatic man therefore does not need a positive penile BV test to discuss treatment, but he does need clinical assessment and prescriptions. In New York State, BV is not eligible for expedited partner treatment, which would provide medication without a clinical visit for the partner.
The trial does not establish whether treating multiple or former partners would help. Direct efficacy evidence is also lacking for partner-treatment strategies involving partners with vaginas or transgender and gender-diverse partners. Those situations call for individualized discussion rather than assuming that results from the studied couples apply.
Partner Treatment and BV Basics
What Male Partner Treatment Involves
The regimen described in current New York State guidance combines metronidazole 500 mg by mouth twice daily for seven days with clindamycin 2% cream applied to the penile head, beneath the foreskin if present, and along the shaft twice daily for seven days. It is prescription partner therapy that requires a clinician's assessment; it is not a reason to use a partner's medication or leftover antibiotics.
In the United States, using clindamycin 2% vaginal cream on the penis for this purpose is off-label. The guidance does not recommend substituting clindamycin 2% vaginal gel for penile use, and effectiveness data are unavailable for clindamycin 1% topical preparations in this setting. A prescriber can specify the intended product and explain how to use it.
Safety, Adherence, and Sex During Treatment
The studied approach treated both partners at the same time. Each partner should complete the course prescribed for them rather than stopping when symptoms improve or changing the regimen independently.
New York State guidance advises avoiding sex until both partners have completed treatment. If sex occurs before then, it advises using condoms. Recently applied clindamycin cream on the penis may weaken condoms, although direct data on penile use are lacking. Ask the prescriber about product-specific instructions rather than relying on an improvised interval between application and sex.
In the trial, some men reported nausea, headache, or a metallic taste, and a few reported penile redness or irritation. No significant adverse events were reported. Those findings cannot predict how an individual will respond; contact the prescriber about concerning effects or questions about whether the medicines are suitable. For alcohol and metronidazole, follow the prescribed product's labeling and the prescriber's advice, which may differ from the CDC's general guidance.
Evidence, Benefits, and Important Limitations
In the Australian StepUp trial, women with symptomatic BV received standard BV treatment, while male partners in the intervention group received both oral metronidazole and topical penile clindamycin. Within 12 weeks, BV recurred in 24 of 69 women (35%) in the partner-treatment group, compared with 43 of 68 (63%) in the group without male-partner treatment. The trial was stopped early because of the observed benefit.
This result helps explain why advice may seem conflicting. The CDC's 2021 guideline did not recommend routine treatment of sex partners because earlier trials had not shown reduced recurrence. A separate 2021 trial of oral metronidazole alone for men also found no overall benefit. StepUp, reported later, tested a different approach: oral and topical treatment together, given while the partner with BV was treated. Current New York State guidance incorporates that newer evidence by supporting an offer of treatment to an ongoing male partner.
The result does not show that treating a man alone prevents BV recurrence, or that the approach works for every couple. The efficacy trial studied monogamous couples with premenopausal cisgender women and cisgender male partners; effectiveness has not been established for nonmonogamous settings or other partner populations.
Testing, Symptoms, and Other Possible Infections
There is no clinical test available to confirm penile carriage of BV-associated bacteria. The male partners in the StepUp trial did not have symptoms, so partner treatment should not be understood as a diagnosis of 'male BV.'
Penile discharge, sores, painful urination, irritation, or other genital symptoms need clinical evaluation rather than being attributed to a partner's BV. A clinician can assess other possible causes and offer HIV or other STI screening and prevention services when indicated by sexual history. This evaluation is distinct from discussing treatment for an asymptomatic ongoing partner to help reduce BV recurrence.
When to Consult a Healthcare Professional
An ongoing male partner who wants to discuss treatment can see a primary care or sexual-health clinician. The visit provides an opportunity to review whether partner treatment fits the situation, obtain the correct prescriptions, and discuss safe use, possible medication concerns, and questions about sexual activity during treatment. Do not use shared or leftover antibiotics.
The partner with BV should seek reevaluation if symptoms persist or return. Either partner should seek clinical assessment for new genital symptoms, and anyone experiencing concerning effects during treatment should contact their prescriber. Concurrent male-partner treatment is a newer option supported by an important trial and current New York State guidance, but it is not a universal cure for recurrent BV.
Bacterial vaginosis (BV) is a change in the vaginal microbiota involving a decrease in Lactobacillus bacteria; a person without a vagina cannot develop BV itself, though a male partner can carry BV-associated bacteria on the penis without symptoms. The bacteria can be shared between ongoing sexual partners, but BV is not caused by a single identifiable pathogen, and a diagnosis does not indicate sex outside the relationship. Treating an ongoing male partner aims to reduce bacterial exchange and lower the chance of BV recurrence, not to cure a male disease; the type of treatment matters, as earlier trials of oral metronidazole alone showed no overall benefit, while a newer trial (StepUp) found a reduction in recurrence when male partners used both oral metronidazole and topical penile clindamycin while their partners received BV treatment.
Current New York State guidance supports offering this concurrent treatment to ongoing male partners of persons with symptomatic BV, though the strongest evidence comes from monogamous couples of premenopausal cisgender women and cisgender male partners, and effectiveness has not been established for nonmonogamous or other partner populations. The recommended regimen combines metronidazole 500 mg orally twice daily for seven days with clindamycin 2% cream applied to the penile head, beneath the foreskin if present, and along the shaft twice daily for seven days, requiring a clinician's assessment and prescription. Both partners should complete their full prescribed courses, and New York State guidance advises avoiding sex until both have finished treatment, suggesting condom use if sex occurs before then, as recently applied clindamycin cream may weaken condoms. Reported side effects in men included nausea, headache, a metallic taste, and occasional penile redness or irritation, with no significant adverse events noted; no clinical test exists to confirm penile carriage of BV-associated bacteria, so partner treatment should not be understood as a diagnosis of 'male BV.' Individuals with penile discharge, sores, painful urination, or other genital symptoms should seek clinical evaluation for other causes, including STI screening. Anyone experiencing concerning effects during treatment or symptoms that persist or return should contact their prescriber or seek reevaluation.
Published by: Centers for Disease Control and Prevention
Published by: New England Journal of Medicine
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