It’s the cycle that drives people crazy. You get the familiar, fishy odor and thin discharge. You go to the doctor, take the metronidazole, and everything clears up. Then, like clockwork, it’s back two weeks later.
For years, doctors told us the same thing: "Men don’t need treatment. You can't catch it from him."
But honestly? That advice is getting a massive reality check. While a man can’t "have" bacterial vaginosis in the sense of an infection in his own body, the question of whether can men pass BV bacteria back and forth is finally being answered with a resounding "yes."
The medical world is currently undergoing a bit of a shift. Recent studies, including a landmark trial published in the New England Journal of Medicine in March 2025, suggest that we’ve been looking at this all wrong.
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The Old Myth: "It’s Just Your pH"
Most of us grew up hearing that BV is just a "balance" issue. Douching, soaps, or maybe a new partner’s semen messing with your acidity. While that's partially true, it treats the vagina like an isolated island.
Here’s the thing: Men carry the exact same bacteria—like Gardnerella vaginalis and Prevotella—in their urethras and under their foreskins. They don't get symptoms because they don't have a vaginal environment for those bacteria to overgrow in. They are essentially silent carriers.
Think of it like a game of bacterial ping-pong. You clear the infection with antibiotics, but if your partner is still "holding" those specific strains of bacteria on his skin or in his urethra, he can pass them right back during sex. Suddenly, your healthy flora is overwhelmed again.
What the 2025 NEJM Study Actually Proved
If you’ve been struggling with recurrent BV, this is the data you need to show your doctor. Researchers in Australia conducted a massive trial (the StepUp study) involving 164 couples.
They split them into two groups:
- One group where only the woman was treated (the current standard of care).
- One group where both the woman and her male partner were treated.
The results were kinda shocking. In the group where only the woman took meds, the BV came back in 63% of cases within 12 weeks. In the group where both partners were treated? That number dropped to 35%.
The researchers, led by Professor Catriona Bradshaw from the Melbourne Sexual Health Centre, actually had to stop the study early. Why? Because it was becoming "unethical" to keep denying men treatment when it was so clearly helping their partners stay healthy.
How Men Actually "Pass" the Bacteria
It’s not just about semen. It’s about the penile microbiome.
Basically, the skin of the penis and the area inside the tip (the urethra) host a whole community of microbes. Studies have shown that the makeup of a man's penile bacteria can actually predict whether his partner will develop BV with high accuracy.
- Circumcision status matters: Men who are uncircumcised tend to harbor more BV-associated bacteria because the foreskin provides a warm, moist environment where these microbes thrive.
- The Urethral Reservoir: Even if a man washes thoroughly, the bacteria live inside the urethra. During sex, these are transferred into the vaginal canal.
- Biofilms: This is the scary part. Bacteria like Gardnerella can form a "biofilm"—sort of a protective sugary shield—that makes them much harder to kill with standard antibiotics. If a man passes a biofilm-forming strain to you, your "balance" doesn't stand a chance.
Why Doesn't Every Doctor Treat the Male Partner?
You’d think this would be a "no-brainer," right? But medicine moves slowly.
The CDC guidelines (as of early 2026) still don't routinely recommend treating male partners. This is mostly because older studies from the 80s and 90s didn't show much benefit. However, experts now point out that those old studies used weak doses or only gave the men oral pills.
Modern research suggests that for a man to "clear" the bacteria, he needs a "double whammy": oral antibiotics (usually Metronidazole) and a topical antibiotic cream (like Clindamycin) applied directly to the penis for seven days.
The Frustrating Reality of the "Not an STI" Label
Technically, BV isn't classified as a classic Sexually Transmitted Infection like Chlamydia or Gonorrhea. You can get BV without having sex. You can get it from douching or even just hormonal shifts.
But for people in long-term relationships, it behaves exactly like an STI.
If you're seeing a new partner, your risk of BV skyrockets. If you have a regular partner and keep getting reinfected, the "it's not an STI" label feels like a slap in the face. It's more accurate to say it's a "sexually enhanced" condition.
Practical Steps to Break the Cycle
If you are tired of the constant trips to the pharmacy, it might be time to take a more aggressive approach with your partner.
1. Have the "Double Treatment" Talk
Bring the 2025 NEJM study results to your provider. Ask specifically about treating your partner with both oral metronidazole (400mg or 500mg twice daily for 7 days) and 2% clindamycin cream.
2. Synchronize Your Meds
Both of you need to start and finish your treatment at the exact same time. No "I'll start mine Monday and you start yours Wednesday." It has to be a coordinated strike.
3. The Seven-Day Rule
No sex. None. Not even with a condom. Most doctors recommend waiting at least seven days after both of you finish the medication. This gives your vaginal microbiome time to rebuild its "good" bacteria (Lactobacillus) without being disrupted.
4. Condom Usage (Temporarily)
Even after treatment, using condoms for a few months can help. It prevents the exchange of fluids while your body is still in the "recovery" phase. Semen is alkaline, and a vagina trying to heal from BV needs to stay acidic.
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5. Consider the "Biofilm" Factor
If standard treatment fails, some specialists recommend using a boric acid suppository for a few nights before starting antibiotics. This helps break down the bacterial biofilm so the meds can actually reach the "bad" bugs.
Actionable Insights for Recovery
Breaking the loop of reinfection requires looking at both sides of the equation.
- Verify the script: Ensure your partner is getting both the cream and the pills. Pills alone often fail to clear the bacteria from the skin of the penis.
- Check for non-sexual triggers: While you're treating the "transmission" side, don't forget the basics. Stop using scented soaps, quit douching entirely, and stick to breathable cotton underwear.
- Probiotics might help, but they aren't a cure: Taking Lactobacillus rhamnosus GR-1 or Lactobacillus reuteri RC-14 can help "reseed" the good stuff, but they usually can't fight off an active infection passed from a partner on their own.
Stop letting the "men can't pass BV" myth keep you in a cycle of discomfort. The science has caught up, and it's okay to demand a treatment plan that actually accounts for how bacteria move between partners.