BV stands for bacterial vaginosis, the most common vaginal infection in women of reproductive age. It affects roughly 23% to 29% of women globally, making it more prevalent than yeast infections, though it’s often confused with them. BV isn’t a sexually transmitted infection, but rather an imbalance in the natural bacteria that live in the vagina.
What Bacterial Vaginosis Actually Is
A healthy vagina contains a community of bacteria dominated by beneficial species that produce lactic acid, keeping the environment acidic (a pH below 4.5). This acidity acts as a natural defense, preventing harmful organisms from gaining a foothold. BV develops when that balance shifts: the beneficial bacteria decline and are replaced by an overgrowth of other species that thrive in less acidic conditions.
When these replacement bacteria take over, they break down the protective mucus layer lining the vaginal walls. This raises the pH above 4.5 and reduces lactic acid levels. The result is an environment where harmful bacteria can flourish, producing waste products that cause the hallmark symptoms of BV. It’s not a single “bug” causing the infection. It’s an entire ecosystem tipping out of balance.
Common Symptoms
The most recognizable symptom of BV is a thin, grayish-white vaginal discharge with a distinct fishy odor, which often becomes stronger after sex. Some women also notice mild itching or burning during urination. But here’s what surprises many people: up to half of women with BV have no noticeable symptoms at all, which means it can go undetected for a long time.
BV discharge looks and smells different from a yeast infection. Yeast infections typically produce a thick, white, cottage cheese-like discharge with itching but little odor. If you’re unsure which you’re dealing with, the distinction matters because the treatments are completely different.
What Raises Your Risk
Several factors can disrupt the vaginal bacterial balance and increase the likelihood of developing BV:
- Douching washes away the beneficial bacteria that maintain vaginal acidity. Even occasional douching can trigger an imbalance.
- New or multiple sexual partners introduce different bacteria into the vaginal environment, which can shift the microbial balance.
- Not using condoms allows more direct bacterial exchange during sex.
BV can occur in women who have never had sex, though it’s less common. Hormonal changes, antibiotics for other conditions, and even certain soaps or body washes can also play a role in disrupting the bacterial community.
How BV Is Diagnosed
Diagnosis typically involves a combination of a physical exam and lab testing. A healthcare provider may check the vaginal pH, since a reading above 4.5 suggests BV rather than normal flora. They may also look at a sample of vaginal discharge under a microscope for “clue cells,” which are vaginal cells coated with bacteria, a signature sign of BV.
The most precise diagnostic tool is a lab scoring system that evaluates a stained sample of vaginal fluid on a scale of 0 to 10. A score of 0 to 3 indicates a healthy bacterial balance, 4 to 6 is intermediate, and 7 to 10 confirms BV. This method is considered the gold standard in clinical research, though many providers diagnose BV based on symptoms and a simpler in-office evaluation.
Treatment Options
BV is treated with prescription antibiotics, available as either oral pills or vaginal creams and gels. A typical course lasts five to seven days. Most women notice improvement within a few days of starting treatment, and the infection usually clears by the end of the course.
The frustrating part is what happens afterward. Between 50% and 80% of women experience a recurrence within 6 to 12 months of finishing antibiotics. This high recurrence rate is one of the most challenging aspects of BV. The antibiotics clear the overgrown bacteria, but they don’t always restore the beneficial species to levels strong enough to maintain balance long-term.
Why Recurrence Is So Common
Because BV is a community-level disruption rather than a single infection, killing off the harmful bacteria doesn’t guarantee the beneficial ones will bounce back. Think of it like weeding a garden: removing the weeds doesn’t automatically regrow the flowers. If the conditions that caused the imbalance in the first place haven’t changed (ongoing douching, a new sexual partner, or other disrupting factors), the same shift can happen again.
For women with frequent recurrences, providers sometimes recommend extended or suppressive antibiotic courses. Reducing known risk factors, particularly douching and unprotected sex with new partners, also helps lower the odds of another episode.
BV During Pregnancy
BV takes on extra significance during pregnancy. It has been linked to preterm delivery, early miscarriage, low birth weight, and postpartum uterine infections. Preterm birth in particular carries serious risks for the infant, including respiratory illness and other complications. Pregnant women with symptoms of BV are typically screened and treated, though routine screening of all pregnant women regardless of symptoms remains a topic of ongoing clinical discussion.
BV vs. Other Vaginal Infections
BV is frequently mistaken for yeast infections or even sexually transmitted infections like trichomoniasis. The key differences come down to discharge characteristics and underlying cause. BV produces a thin, fishy-smelling discharge caused by bacterial imbalance. Yeast infections cause thick, odorless discharge driven by fungal overgrowth. Trichomoniasis, which is caused by a parasite, often produces a frothy, yellowish-green discharge with irritation.
Getting the right diagnosis matters because over-the-counter yeast infection treatments won’t resolve BV, and untreated BV can increase susceptibility to sexually transmitted infections by weakening the vagina’s natural protective barriers.