What is bacterial vaginosis (BV)?

Elizabeth Morrill
Elizabeth Morrill
Published Mar 27, 2023
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Key Points:

  • Bacterial vaginosis (BV) is caused by an imbalance of “good” bacteria (Lactobacilli) and “bad” bacteria (anaerobes like Gardnerella vaginalis) in the vagina.
  • Bacterial vaginosis can occur whenever something disrupts the chemistry in the vagina, including douching or using irritating vaginal products. There’s also an increased risk of bacterial vaginosis if you are a woman who has sex with women, if you have a new sex partner or if you have multiple sex partners.
  • Bacterial vaginosis is treated with antibiotics. It’s important to talk to a medical provider about your symptoms because BV can cause more serious issues if left untreated, especially if you’re pregnant.


Bacterial vaginosis (BV) is the most common vaginal condition in people with female anatomy who are between the ages of 15 and 44. It happens when there’s an imbalance of “good” and “bad” bacteria in the vagina.

Symptoms of bacterial vaginosis are usually pretty mild, and some people don’t have any symptoms at all. However, BV can increase the risk of catching sexually transmitted infections (STIs) because of the way the condition impacts vaginal chemistry. Bacterial vaginosis can also cause more serious problems, especially if you’re pregnant.

Bacterial vaginosis is treated with antibiotics. If you think you might have BV, it’s important to talk to a medical provider to make sure you get the right treatment.

What is bacterial vaginosis?

Bacterial vaginosis is an imbalance of “good” and “bad” bacteria in the vagina. When there aren’t enough “good” bacteria, other types can grow out of control and cause symptoms like vaginal discharge and a fishy odor.

A healthy vagina contains many different types of bacteria. The most common type is called Lactobacillus. It’s important to have mostly lactobacilli in the vagina because this type of bacteria helps protect the vagina from other, more problematic kinds of infection.

If there aren’t enough lactobacilli, other types of bacteria can grow unchecked. The most common bacteria associated with bacterial vaginosis is Gardnerella vaginalis.

Lactobacilli prevents infection in many different ways:

  • By producing lactic acid and other protective antimicrobial byproducts. Lactic acid lowers the pH of the vagina, making it more difficult for other infectious organisms to grow.
  • By competing for nutrients, so other “bad” bacteria can’t get the fuel they need to reproduce.
  • By taking up physical space, preventing problematic bacteria from growing and spreading, especially bacteria that cause sexually transmitted infections.

Is bacterial vaginosis an STI?

Bacterial vaginosis isn’t an STI. Sometimes people mistake BV symptoms for other problems like chlamydia or a yeast infection because it can cause vaginal discharge and an unpleasant odor.

The best way to know if you have bacterial vaginosis is to talk to a medical provider who can perform tests. However, your symptoms can also provide clues.

Bacterial vaginosis typically causes a thin, milky discharge along with a fishy odor. BV can also cause burning with urination and vaginal itching.

  • Chlamydia may also cause discharge, but it tends to be light and transparent
  • Urinary tract infections (UTIs) can cause burning with urination, but it rarely causes discharge
  • Yeast infections can cause vaginal itching, but it is also typically associated with a thick, cottage-cheese type of discharge

Even though BV is not an STI, bacterial vaginosis can increase the risk of developing an STI, especially HIV. One of the reasons this can happen is because when there aren’t enough Lactobacillus to protect the vagina, other bacteria can take hold more easily.

It’s also important to know that sex can increase the risk of developing BV. While researchers aren’t exactly sure how this works, certain activities can make it more likely to develop BV, including:

  • Having a new sexual partner
  • Having more than one sexual partner 
  • People assigned female at birth (AFAB) who have sex with other AFAB people

What causes bacterial vaginosis?

BV can be caused by anything that disrupts the natural balance of bacteria in the vagina. This might include douching, using vaginal deodorants or applying other irritating products like scented tampons.

Sex can also lead to BV if your partner’s natural chemistry impacts the flora in your vagina.

Is bacterial vaginosis contagious?

Bacterial vaginosis isn’t contagious and BV doesn’t spread from one person to another. Sexual activity increases the risk of developing BV because of the way it can impact your vaginal microbiome.

There’s no definite way to prevent BV, but you can help reduce the chances by maintaining a healthy vaginal flora:

  • Do not douche or use other irritating products in the vagina
  • Practice good hygiene by always wiping front to back after using the bathroom and washing any sex toys properly after use
  • Limit your number of sex partners since more sex partners are linked to an increased risk of bacterial vaginosis
  • Use latex condoms or dental dams during sex
  • Wear cotton underwear to help wick away moisture that can impact bacterial growth

Online treatment for bacterial vaginosis

Bacterial vaginosis is treated with a short course of antibiotics. It’s important to talk to a medical provider about any symptoms of bacterial vaginosis, including new or unusual discharge or odor, because BV can cause more serious problems.

Long-term complications of bacterial vaginosis can include:

  • Increased risk of sexually transmitted infection, including HIV
  • Pre-term delivery and other birth-related complications
  • Pelvic inflammatory disease
  • Infertility and miscarriage
  • Increased risk of infection after pelvic surgery

There are no over-the-counter medications available for bacterial vaginosis. In fact, some over-the-counter products used for yeast infection can actually make BV worse.

Still have questions about BV? Dr. B can help.


Abou Chacra, L., Fenollar, F., & Diop, K. (2022). Bacterial Vaginosis: What Do We Currently Know?. Frontiers in cellular and infection microbiology, 11, 672429. https://doi.org/10.3389/fcimb.2021.672429

Centers for Disease Control and Prevention. (2022, January 5). Bacterial Vaginosis - CDC Basic Fact Sheet. Centers for Disease Control and Prevention. Retrieved February 6, 2023.

Goje, O. (2021, April 31). Bacterial vaginosis (BV) - gynecology and obstetrics. Merck Manuals Professional Edition. Retrieved February 6, 2023.

Parenthood, P. (n.d.). What is bacterial vaginosis?: Symptoms, signs and causes. Planned Parenthood. Retrieved February 6, 2023.

Ravel, J., Moreno, I., & Simón, C. (2021). Bacterial vaginosis and its association with infertility, endometritis, and pelvic inflammatory disease31193-5/fulltext). American Journal of Obstetrics and Gynecology, 224(3), 251–257. https://doi.org/10.1016/j.ajog.2020.10.019

Valenti, P., Rosa, L., Capobianco, D., Lepanto, M. S., Schiavi, E., Cutone, A., Paesano, R., & Mastromarino, P. (2018). Role of Lactobacilli and Lactoferrin in the Mucosal Cervicovaginal Defense. Frontiers in immunology, 9, 376. https://doi.org/10.3389/fimmu.2018.00376

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