BV stands for bacterial vaginosis, a common vaginal condition caused by an imbalance of bacteria. It’s the most common vaginal condition in women ages 15 to 44, and while it often clears up with a short course of antibiotics, it has a frustrating tendency to come back.
What Happens Inside the Vagina
A healthy vagina is home to a community of bacteria, and one group in particular keeps things in balance. These beneficial bacteria produce hydrogen peroxide, which creates a mildly acidic environment that prevents other organisms from growing out of control.
BV develops when those protective bacteria decline and other types of bacteria multiply to fill the gap. One species in particular tends to kick off the process by forming a sticky layer, called a biofilm, along the vaginal walls. That biofilm then becomes a welcoming surface for additional bacteria to latch onto and multiply. The result is a shift from a healthy, slightly acidic environment to one dominated by bacteria that thrive in less acidic conditions.
Common Symptoms
The hallmark symptom is a thin, grayish-white or yellowish discharge that’s often heavier than normal. Many people also notice a distinct fishy smell, which can become stronger after sex. The odor happens because semen raises the vaginal pH, which activates the compounds produced by the overgrown bacteria.
BV doesn’t typically cause significant pain or itching. Some mild irritation is possible, but intense burning or soreness points more toward a different condition. It’s also worth noting that many people with BV have no symptoms at all and only discover it during a routine exam.
BV vs. Yeast Infections
These two conditions are easy to confuse since both involve unusual discharge, but they look and feel quite different. BV produces a thin, grayish discharge with a fishy odor. A yeast infection produces a thick, white, cottage cheese-like discharge that usually doesn’t smell much at all.
The other major difference is discomfort. BV rarely causes pain, while yeast infections commonly cause itching, burning, and soreness, especially during or after sex. Because the treatments are completely different, getting the right diagnosis matters. Over-the-counter yeast treatments won’t help BV, and antibiotics for BV won’t clear a yeast infection.
How BV Is Diagnosed
Doctors typically diagnose BV using a combination of bedside tests. They’ll look at the discharge (thin, uniform, grayish), check whether vaginal pH is above 4.5 (higher than the normal acidic range), and examine a sample under a microscope. A fishy smell released during the sample preparation is another key indicator. Meeting at least three of these four criteria confirms the diagnosis.
In some cases, a lab-based scoring method is used instead. A vaginal swab is stained and examined under a microscope to count the relative numbers of protective bacteria versus the types associated with BV. A score of 7 or higher (on a 0 to 10 scale) confirms the condition.
What Causes It
BV isn’t a sexually transmitted infection in the traditional sense, but sexual activity is one of its strongest risk factors. New partners, multiple partners, and unprotected sex all increase the likelihood. Semen and menstrual blood both have a higher pH than the vagina, and when that balance gets disrupted repeatedly, BV can take hold.
Douching is another well-established risk factor. It washes away protective bacteria and directly raises vaginal pH. Scented soaps, bubble baths, and other products used internally can have a similar effect. The vagina is largely self-cleaning, so the simplest prevention strategy is to let it do its job and avoid introducing products that disrupt its natural environment.
Treatment
BV is treated with prescription antibiotics, either taken by mouth for about seven days or applied as a vaginal cream or gel for five to seven days. Both approaches are effective, and the choice often comes down to personal preference and convenience. Symptoms typically improve within a few days of starting treatment.
The bigger challenge is recurrence. More than 50% of people experience BV again within three to six months of treatment, and up to 66% have a recurrence within a year. That high relapse rate has led researchers and clinicians to rethink the approach.
New Guidance on Partner Treatment
In 2025, the American College of Obstetricians and Gynecologists issued updated recommendations for the first time advising that male sexual partners of people with recurrent BV be treated with antibiotics at the same time. The logic is straightforward: if the bacteria responsible for BV can be harbored by a partner and reintroduced during sex, treating only one person creates a cycle of reinfection.
For people with same-sex partners or those experiencing BV for the first time, the guidelines recommend a shared decision-making conversation with a healthcare provider about whether concurrent partner treatment makes sense. This shift reflects growing evidence that BV behaves more like a sexually shared condition than previously recognized, especially in cases that keep coming back.
Reducing Your Risk of Recurrence
Beyond partner treatment, a few practical habits can help keep vaginal bacteria in balance. Avoid douching entirely. Use only water or a mild, unscented cleanser on the external genital area. Wearing breathable cotton underwear and changing out of wet swimwear or workout clothes promptly can also help maintain a healthy environment.
Condom use reduces the frequency of BV recurrence by limiting exposure to semen, which temporarily raises vaginal pH. If you notice that BV tends to flare around your period (menstrual blood also raises pH), that pattern is common and worth mentioning to your provider, as it can help guide a prevention strategy tailored to your cycle.