What Is BV? Bacterial Vaginosis Meaning, Symptoms, and Causes

Bacterial vaginosis (BV) is a common condition that affects many women, yet it often remains misunderstood or misdiagnosed. If you've ever experienced unusual discharge or a fishy smell and wondered what might be causing it, you're not alone.

In this ultimate guide to BV, we'll break down everything you need to know — from its causes and symptoms to treatment options and prevention tips.

Key takeaways

• BV is a vaginal infection caused by an overgrowth of harmful bacteria, which throws off the natural balance of your vaginal microbiome.
• The main symptoms are thin, watery gray or white discharge and a fishy odor, often more noticeable after sex. Many people have no symptoms at all.
• Top causes include unprotected sex (especially with new or multiple sex partners), hormonal shifts (periods, pregnancy, birth control, menopause), smoking, stress, and douching.
• BV is caused by bacteria, while yeast infections are caused by Candida fungus. Yeast infections typically bring thick, cottage cheese-like discharge and itching, while BV usually doesn't.
• Test at home with the Evvy Vaginal Microbiome Test to identify exactly which bacteria are present.

What is BV?

Bacterial vaginosis is a vaginal infection caused by the overgrowth of bad bacteria in your vaginal microbiome. 

A healthy vaginal microbiome is composed mostly of Lactobacilli, lactic acid-producing bacteria that fight pathogens and help prevent infections. 

When Lactobacilli dominance is disrupted, your vaginal pH can rise, allowing other types of bacteria to grow and cause an imbalance (known in medicine as dysbiosis). This causes symptoms like discomfort, itching, and unusual vaginal discharge. ‍

If you’re dealing with bacterial vaginosis, you’re far from alone. According to the Centers for Disease Control (CDC), bacterial vaginosis is the most common vaginal condition in women ages 15-44, and almost 30% of people with vaginas get bacterial vaginosis each year.

BV subtypes

For decades, BV has been treated as a single condition. But BV can look very different from person to person, which is part of why it often comes back after treatment.

New research from Evvy shows that BV isn’t a single biological condition but a spectrum of microbial states, even when symptoms look the same. This means people with the same diagnosis can have very different bacteria driving their symptoms, which is why the same treatment works for some but not others. 

Here are the main subtypes of BV identified in Evvy’s research:

• Typical BV: The classic presentation of BV, driven by overgrowth of BV-associated bacteria like Gardnerella and Prevotella, alongside low levels of protective Lactobacillus.
• Transitional BV: A microbiome in flux — either moving into BV or on its way back to a healthier state. This type is dominated by Lactobacillus iners, which offers weaker protection and allows BV bacteria to linger.
• Lacto-Dominant BV: A protective Lactobacillus foundation is still there, but BV-associated bacteria appear at lower levels.
• Biofilm BV: Driven by certain BV-associated bacteria that form biofilms (protective structures that shield bacteria and make them harder to reach).
• Mixed BV: Categorized by more than one disruptive pattern, with both BV- and AV-associated bacteria present.‍
• Atypical BV: Some individuals show more complex patterns, including certain less common gram-positive anaerobes often missed by standard testing.

BV symptoms 

BV doesn't always cause symptoms, and up to 84% of people with BV don't know they have it. When symptoms do appear, though, the main ones are:

• Increased discharge that's thin, gray, or white, and watery
• A strong fishy smell, especially noticeable after having sex
• Mild itching or burning when peeing (less common). 

Symptoms alone aren't enough for a diagnosis. Many vaginal infections look similar, and self-diagnosis is only accurate about 56% of the time.

What causes BV?

‍Bacterial vaginosis happens when the natural balance of your vaginal microbiome is thrown out of whack, and anaerobic bacteria take over.

Research shows that certain activities or events may increase or decrease your risk of BV. Some of these risk factors include:

• Sex (specifically, with multiple sex partners or a new sex partner)
• Hormonal fluctuations (e.g., birth control, pregnancy, and menopause)
• Your period
• Smoking cigarettes
• Stress‍
• Douching and using vaginal hygiene products.

However, researchers still aren't sure what the exact cause of BV is, or how some women get it.

If you’re shocked that this is the best available answer for a condition that affects one in three women, you’re not alone. This is why Evvy exists! The vaginal microbiome and bacterial vaginosis are massively understudied, and it’s time women and people with vaginas got the research and care they deserve. ‍‍

The connection between BV and sex

BV has long been considered not a sexually transmitted infection (STI), and you can indeed develop BV without being sexually active. Because it’s defined as an imbalance in the vaginal microbiome, the traditional view has been that you can’t “catch” BV from a partner. However, this understanding is starting to shift.

New research, including a notable study published in The New England Journal of Medicine (NEJM), suggests that BV may be sexually transmitted. Scientists have found BV-associated bacteria in the male urethra and on penile skin, and women with regular sexual partners are twice as likely to experience BV recurrence. Even more compelling, the composition of a male partner’s microbiome may help predict a woman’s risk of BV — highlighting that BV might not just be a vaginal issue, but part of a shared bacterial environment between partners.

There’s still no official consensus, but the tides are changing as evidence mounts that BV could be sexually transmissible after all.

Hormones and BV 

Hormones play a role in shaping the vaginal microbiome. Estrogen, in particular, is an important variable in the health of your Lactobacilli, the bacteria that create a lactic acid-dominant environment in the vagina. Anything that changes estrogen levels can affect the vaginal microbiome. 

This means that it’s important to pay extra attention to your vaginal microbiome anytime your hormones fluctuate, starting with:

• Your menstrual cycle
• Becoming pregnant
• Going through menopause
• Going on or changing birth control methods.

What happens if BV is left untreated?

The bacteria present in your vaginal microbiome influence the risk of a variety of other health issues, and untreated BV increases your risk of serious complications, including: 

• STIs like chlamydia, gonorrhea, trichomoniasis, herpes, HPV, and HIV 
• Pelvic inflammatory disease (PID)
• Fertility issues and failed in-vitro fertilization (IVF)
• Pregnancy complications like miscarriage, preterm birth, low birth weight, and preeclampsia 
• Gynecological cancers such as ovarian, cervical, or endometrial cancer
• Cervicitis
• Toxic shock syndrome (TSS). 

What is the difference between BV and a yeast infection? ‍

Bacterial vaginosis is not the same thing as having a yeast infection, which is caused by Candida (yeast). The main underlying difference is that yeast infections are caused by an overgrowth of Candida (a type of fungus), whereas bacterial vaginosis is caused by an overgrowth of various bacteria, such as Gardnerella. 

Though the symptoms of these two vaginal infections may overlap, yeast infections are typically characterized by a specific type of vaginal discharge (often described as cottage cheese-like) and itchiness, while bacterial vaginosis is mostly associated with a fishy odor and thin, white or gray vaginal discharge.‍

How is BV diagnosed? ‍

The world of vaginal diagnostics is complicated, but there are two traditional ways to diagnose bacterial vaginosis. The first is symptom-based, based on the Amsel criteria. An Amsel criteria diagnosis is when you have three of the four following symptoms:

• White discharge
• Clue cells
• A vaginal pH over 4.5
• A strong fish-like odor. 

A slightly more specific way to diagnose BV is with a Nugent score. Using the Nugent score, a vaginal smear is examined under a microscope for three bacterial morphotypes: Lactobacillus, Gardnerella, and curved gram rods.  

A score is then created based on how many of each type have been counted, essentially looking for low, intermediate, or high diversity of bacteria in the sample. A score under 4 is considered healthy, 4-7 is considered intermediate, and 7-10 is considered high diversity (aka BV).  

You may have noticed that “high diversity” isn’t a very specific diagnosis — and you’re right. Unfortunately, current diagnostic measures don’t tell you much about what other bacteria are present or any other relevant information about how they’re interacting in your vaginal microbiome. 

This is why we’ve created an at-home vaginal microbiome test, so you can understand all the bacteria present in your microbiome. Though it’s not a diagnostic test and shouldn’t replace your doctor's advice, it can help you uncover what strains are present and in what capacity to understand how they may contribute to any symptoms.

Where to get a BV test

You can order BV tests online, but Evvy’s Vaginal Microbiome Test stands out by using the most comprehensive metagenomic sequencing technology available. It delivers physician-reviewed results and is processed in a CLIA, CLEP, and CAP-certified lab. The test can be taken from the comfort of your own home, with results delivered in just a few days. If BV-causing bacteria are detected, eligible users can access a personalized, prescription treatment program developed by a licensed provider. Our precision care platform uses your test results and health history to create a treatment plan tailored specifically to you.

How to treat BV 

You can treat bacterial vaginosis with antibiotics prescribed by a doctor. Commonly used antibiotics include clindamycin and metronidazole, as well as alternatives such as tinidazole or secnidazole.

Unfortunately, these are not effective long-term solutions for treating bacterial vaginosis. While antibiotics clear up to 85% of bacterial vaginosis cases within a month, over half of these patients will experience a recurrence within 6 months. Some studies show recurrence rates as high as 80%, three months after “effective treatment.” Doesn’t sound so effective to us! 

It’s important to note that each antibiotic works better against some strains of bacteria than others, and some spare protective bacteria while others do not. When battling recurrent bacterial vaginosis, knowing which specific bacteria are present in your microbiome may be useful in selecting an antibiotic. 

Aside from medication, there are some everyday behaviors you can do to prevent bacterial vaginosis from coming back: 

• Avoid douching and feminine hygiene products (like scented soaps or vaginal deodorants). Douching upsets the normal balance of bacteria in your vagina.
• Practice safe sex and use condoms or dental dams (yes, even during oral sex).
• Cover sex toys with a condom during partnered sex, and wash them with unscented soap/water after each use. 
• Wipe front to back after using the bathroom.
• Change your period products within the appropriate timeframe.
• Quit smoking.

How to test for BV

BV testing typically involves a healthcare provider performing a physical exam and collecting a sample of vaginal discharge. The sample is analyzed under a microscope to check for harmful bacteria linked to BV.

You can test for BV-causing bacteria using Evvy's Vaginal Microbiome Test. It works just like a test you'd do in a doctor's office, but from the comfort of your own home. All you have to do is: 

• Order your test kit online
• Collect a vaginal swab sample (it only takes a few minutes)
• Send it back in the prepaid mailer provided
• Get physician-reviewed results in just a few days. 

Evvy uses metagenomic sequencing (not PCR), the most comprehensive technology available, to detect and quantify specific bacteria such as Gardnerella vaginalis, Prevotella spp., and Atopobium vaginae. Rather than a simple yes/no result, you get a full breakdown of your vaginal microbiome to help pinpoint what's actually driving your symptoms. The test is processed in a CLIA, CLEP, and CAP-certified lab, and if BV-causing bacteria are detected, eligible users can access a personalized prescription treatment plan from a licensed provider.

‍Why does my BV keep coming back?

Recurrent bacterial vaginosis is pretty common because it tends to resist treatment or return after successful treatment. 

One reason is biofilm formation: bacteria-made structures that shield themselves from antibiotics, making some standard treatments less effective against certain BV-causing bacteria. Re-infection through unprotected sex with a partner can also play a role, since BV-associated bacteria can be passed back and forth.

This could be why BV has a high recurrence rate, but we're still learning about the exact role that biofilm plays in BV. 

FAQs about bacterial vaginosis 

What causes you to have BV?

BV occurs when the balance of bacteria in the vagina is disrupted, allowing harmful bacteria to outnumber helpful ones. This can be caused by a few things, like having new or multiple sexual partners, douching, hormonal changes (during your period, pregnancy, or menopause), using intrauterine devices (IUDs), taking antibiotics, using scented vaginal products, and smoking. These factors mess with the natural bacteria in the vagina and increase the chance of getting BV. Knowing about and avoiding these triggers can help you maintain a healthy balance and avoid BV.

Is BV a form of STD?

BV isn’t officially classified as a sexually transmitted disease (STD), but emerging research suggests it can be sexually transmitted. While BV has traditionally been seen as a vaginal imbalance caused by factors like douching, hormonal changes, or certain products, studies now show that sexual activity — especially with new or multiple partners — can play a direct role in its transmission. So, although it’s not labeled a typical STD, there’s growing evidence that BV can be passed between partners, making sexual behavior an important factor in its development and recurrence.

Can you get BV without having sex?

Yes, you can develop bacterial vaginosis even if you're not sexually active. Although it can be transmitted sexually, it’s not the only way to develop BV. Your period, smoking cigarettes, and using douches can all increase your risk of developing bacterial vaginosis. 

Where do I go to get tested for BV?

You can get tested for BV by visiting your healthcare provider, who can perform a pelvic exam and send a sample to a lab for testing. If you prefer a more convenient option, you can order Evvy’s Vaginal Microbiome Test online. It’s an at-home test that detects BV-causing bacteria using advanced metagenomic sequencing. You collect your sample in the comfort of your own home and receive results within a few days. If BV bacteria are detected, eligible users can also access a personalized prescription treatment program through Evvy’s precision care platform. 

Will BV go away on its own? 

Sometimes, bacterial vaginosis can go away on its own. It often doesn’t cause symptoms, so your immune system might get rid of it before you even notice. However, it’s best to see your healthcare provider if you’re experiencing symptoms of bacterial vaginosis. Untreated BV is linked to a higher risk of contracting sexually transmitted infections, developing pelvic inflammatory disease, and even infertility. 

Does BV ever fully go away?

Yes, BV can fully clear up, especially with the right treatment. Antibiotics clear up to 85% of cases within a month. That said, BV has a high recurrence rate, with over half of people experiencing it again within 6 months. Identifying the specific bacteria causing your BV can help you and your provider choose a more targeted treatment.

Is BV a yeast infection?

No, bacterial vaginosis and yeast infections aren't the same. BV occurs when there's an imbalance in vaginal bacteria, causing a fishy odor and thin, gray discharge, while yeast infections are due to an overgrowth of Candida fungus, resulting in thick, white discharge, itching, and burning. BV is commonly treated with antibiotics, whereas antifungal medications are usually used to treat yeast infections. Knowing the differences between these conditions is important for the right diagnosis and treatment.

Can men get BV?‍

Only people with vaginas can develop BV because, by definition, it is an imbalance in the vaginal microbiome. However, male genitalia can harbor pathogens that disrupt the vaginal microbiome.

What does BV look like on a woman?

BV usually shows up as increased vaginal discharge that's thin and watery, often white or gray in color. The biggest giveaway is a strong fishy smell, which tends to get more noticeable after sex.

What are the most common symptoms of BV?

The most common symptoms are a watery, gray discharge with a strong fishy odor and mild vaginal itching. Many people have no symptoms at all, though.

Can you have BV and not know it?

Yes, very much so. Up to 84% of people with BV don't realize they have it, since symptoms can be mild or completely absent. This is also why self-diagnosis isn't reliable. Studies show it's only about 56% accurate, so testing is the best way to know for sure.