You might have heard the study that came out this year about treating both partners for BV, and if not you’ll definitely want to keep reading. For far too long, women have struggled with recurring Bacterial vaginosis, sometimes with no end in sight. Just take a look at this reddit post from a woman who suffered from chronic BV for years before solving the root of the problem. If you keep getting BV after having sex with your boyfriend or new partner, you’re not crazy. Let’s talk about it.

Bacterial vaginosis, or BV, happens when the balance of bacteria in the vagina shifts. A healthy vaginal microbiome is usually dominated by Lactobacillus bacteria. These bacteria help keep things slightly acidic, which protects against overgrowth of other organisms.

BV occurs when that protective balance changes and other bacteria multiply more than they should. Common symptoms include:

• A strong fishy odor
• Thin gray or white discharge
• A noticeable change in your usual scent
• Mild irritation

BV is extremely common. It is not technically classified as an STI, but it is closely linked to sexual activity. Which brings us to your boyfriend.

BV with a new partner

Every person has a unique microbiome. That includes the bacteria on their skin and genitals. When you start sleeping with someone new, you are introducing a completely new bacterial ecosystem to your body. Even if he is healthy and showers twice a day, his microbiome is still different from yours.

For some people, the vaginal microbiome adapts quickly and seamlessly. For others, that introduction can temporarily disrupt the balance of Lactobacillus, making it easier for BV-associated bacteria to grow. 

Semen can upset your vaginal microbiome

This is another factor that often gets overlooked. The vagina is naturally acidic. Semen is alkaline. When you have unprotected sex, semen can temporarily raise the vaginal pH. That shift makes the environment less ideal for Lactobacillus and more comfortable for other bacteria. For some people, especially those prone to BV, this can trigger symptoms within a day or two. If you are noticing a pattern specifically after unprotected sex, this pH shift could be part of the story. Using condoms can reduce that effect to prevent semen does from altering the vaginal environment in the same way.

Could your partner be reinfecting you with BV?

For a long time, the standard guidance was that male partners did not need treatment for BV because clinical trials did not show a clear benefit. So the default advice became, treat the person with symptoms and move on. But more recent research has started to shift that conversation.

A newer study found that when both partners were treated at the same time, recurrence rates of BV significantly dropped compared to treating only the woman. In other words, addressing the bacterial ecosystem of both people in the relationship reduced the back-and-forth cycle that so many women experience.

Researchers are increasingly looking at BV less like a random imbalance and more like a condition that can involve shared bacteria between partners. Even if a male partner has no symptoms, certain BV-associated bacteria can live on the penis and potentially reintroduce imbalance after treatment.

This does not mean anyone is doing something wrong. It means BV may, in some cases, function more like an STI than we previously understood.

If you are dealing with recurrent BV, it is worth bringing up partner treatment with your healthcare provider. The science is evolving, and treatment approaches are evolving with it.