top of page

What is bacterial vaginosis?

Updated: Jul 29, 2023

In this blog post, missINFORMED covers a condition called bacterial vaginosis and answers the following questions:

What is bacterial vaginosis?

The short: Bacterial vaginosis is a condition caused by an imbalance between the “friendly” and “unfriendly” bacteria in the vagina (1,2).

The vagina is home to an abundance of different bacteria that make up its microbiome (1). The vagina provides warmth and nutrients, which support the growth of bacterial communities (1). Just like the bacteria that live in the gut, not all the bacteria that grow in the vagina are created equal. Some bacteria, the “friendly” bacteria, will return the vagina’s hospitality by helping to protect the vaginal ecosystem from the invasion of harmful or “unfriendly” bacteria (1). While the “friendly” bacteria help to maintain the health of the vagina, an overgrowth of the “unfriendly” bacteria can disrupt it (1). When the “unfriendly” bacteria disrupt the vaginal ecosystem, an individual can develop an infection or other conditions (1). With all this in mind, BV is one of the most common vaginal conditions among individuals of reproductive age (age 14–49) (3). It is caused by a disruption in the natural balance of bacteria in the vagina (2,4). This can be referred to as dysbiosis (2,4). The imbalance means that there are fewer “friendly” bacteria and more “unfriendly” bacteria. While there are some specific species of bacteria that are commonly associated with BV, it is the imbalance between different bacterial populations that are suspected to cause BV (2,4).

What causes bacterial vaginosis?

The short: The exact cause of BV is not clear. However, certain things can make you more likely to develop BV. These include recent antibiotic use, cigarette smoking, use of an intrauterine device (IUD), vaginal douching, and having multiple sexual partners (6).

Unfortunately, the cause of these changes in the vagina’s bacterial population is not completely understood. The vaginal microbiome is dynamic, meaning it can change throughout a person’s lifetime based on hormonal fluctuations and lifestyle habits (1,2,5). For example, the decline in estrogen experienced after menopause can increase an individual’s risk of developing BV (2). Other risk factors that may increase your chance of developing BV include recent antibiotic use, cigarette smoking, use of an intrauterine device (IUD), and vaginal douching (6). Sexual activity (regardless of if your partner does or does not have BV) can increase your chances of developing BV (6).

Vaginal bacterial populations can also naturally differ between individuals (2,5,7,8). Some studies have attributed these differences to race (7). These studies found that certain races, specifically Black folks, were more likely to have vaginas with BV-related bacterial species and higher rates of BV (3,7). However, concluding that these differences are the result of race fails to account for the flexibility and ever-changing nature of bacterial populations, and incorrectly classifies race as a biological category rather than a social one. Bacterial populations are influenced by our age, the environment we grow up/live in, and our day-to-day habits (2,5,8). The current racial disparities that exist in our society and healthcare system are the most likely cause of any differences that exist in vaginal microbiomes and rates of BV between races (8).

What are the symptoms of bacterial vaginosis?

The short: The most common BV symptom is changes to the colour and smell of vaginal discharge (6). It is also very common for some people to show no signs or symptoms of BV (3).

The tricky part about BV is that many people (up to 84%) will show no signs or symptoms (3). The most common symptoms are changes in the colour or smell of vaginal discharge (fluid) (6). Specifically, vaginal discharge may appear off-white, gray, or greenish and it may have an unpleasant “fishy” odour (6). Less common symptoms include itching, a burning feeling after urinating, and pain during sex (6).

If you are showing symptoms of BV, it is really important to see a doctor. Many of the symptoms of BV are similar to other more serious vaginal infections and sexually transmitted infections (STIs). It is important to identify the cause of your symptoms to make sure you treat the right infection. Untreated BV may also cause other health problems. Untreated BV can make it easier for you to catch sexually transmitted infections like genital herpes, gonorrhea, or chlamydia (6,9). It can also make it easier for you to become infected by or spread HIV (9). If undergoing surgery involving the vagina or uterus, untreated BV can make you more likely to develop an infection after surgery (9). If pregnant, untreated BV can increase your likelihood of preterm birth (before 37 weeks or pregnancy) or delivering a baby at a low birth weight (<5.5lbs) (6,9,10).

What should I do if I show symptoms of bacterial vaginosis?

The short: The best thing you can do is go see your healthcare provider. Together you can assess your symptoms, risk of complications, and treatment options. For people showing symptoms, antibiotics are currently the only proven way to treat BV (6,9,10).

First, it is important to understand that BV is very common and should not cause shame. A common misconception is that having BV means you are dirty, but this is not the case (11). In fact, certain cleaning practices like douching or using soap inside the vagina can actually lead to BV (9). Many people struggling with BV may feel embarrassed or distressed by this diagnosis, but there is no need to blame yourself (11). While there are things you can do to help protect yourself, there is no guaranteed way to prevent it. Here is what you can do if you suspect you have BV.

Step 1 is going to see your healthcare provider. It is important for both your health and the health of your sexual partner(s) to find out if you have BV. Your doctor may ask you questions about your medical history and habits to assess your risk of developing BV (6). Your doctor will likely perform a pelvic exam to diagnose BV (6,10). This exam allows them to check for visual signs of BV and collect a small sample of vaginal fluid (6,10). After performing a few tests on the sample, your doctor can let you know if you have BV (6,10). It is helpful to try to schedule this appointment for a day when you are not menstruating (10). It is also helpful not to douche, have sex, or insert anything into the vagina for 24 hours before your appointment (10). These things can introduce new bacteria and irritate the vagina, which could interfere with your exam (10).

The only proven way to treat BV is with the antibiotics Metronidazole or Clindamycin (6,9,10). Both of these antibiotics are available as an oral pill or vaginal cream/gel (6,9). If your symptoms go away while in the middle of taking your antibiotics, be sure to continue with your treatment as prescribed. Completing the full course of antibiotic treatment will help to prevent BV from coming back (9,10). Antibiotic treatment is usually recommended for people who show symptoms of BV and for those who have an additional risk of serious complications (9).

Antibiotic treatment is not always needed. If you do not show symptoms, your doctor may just ask you to monitor yourself for any symptoms without prescribing additional treatment (9). There is no need to worry if this is you! About 30% of BV cases will resolve on their own (6). The best approach is to be open with your doctor about your symptoms and concerns. Together you can assess your options to find a treatment plan that works best for you!

What about probiotics? You may have heard people discuss using probiotic (helpful live microorganisms) supplements to treat BV. This method of treatment has not been well studied. There is not enough evidence that probiotics are an effective treatment for BV (9). The regulation and contents of probiotic supplements vary around the world, so many of these products can be of poor quality (9). More research on and regulation of these products is needed before they can be considered as a useful treatment for BV.

Is there a way to prevent bacterial vaginosis?

The short: There is no guaranteed way to prevent BV (12). However, you can lower your risk by avoiding douching, preventing contact between the vagina and anus, and practicing safe sex (9,12,13).

There is no way to guarantee that you will not get BV (12). Luckily, there are ways to lower your risk.

Avoid douching (9,12). Douching can change the natural balance of bacteria. Lucky for us, the vagina takes care of cleaning itself (see our previous article on vaginal hygiene for more information).

Avoid touching the vagina with anything that has touched the anus (12). Much like the vagina, our digestive system is home to many different kinds of bacteria. While many of these types of bacteria are harmless or even beneficial to our colon, they can be harmful to the vagina. To prevent this bacteria from entering the vagina, always be sure to wipe front to back after going to the bathroom, clean sex toys after every use, and avoid having vaginal sex after anal sex (12).

Use barrier protection when having sex (9,12). Each sexual partner can introduce new bacterial species that may impact the balance of your own vagina (13). Having multiple sex partners can increase your risk of developing BV (9,13). Using barrier protection can help to reduce your risk of developing BV (9,12). Barrier protection includes using condoms when having penetrative sex or using sex toys, and using a dental dam when having oral sex (12). Both of these protection methods can help to prevent new bacteria from being introduced to the vagina (9). Barrier protection also helps to protect you from sexually transmitted infections, which is even more important if you have BV (9,12).

Is bacterial vaginosis contagious?

The short: It is unclear whether BV can spread between sexual partners (6,13). Having sex with someone who has BV or recently had sex with someone who has BV does not guarantee that you will develop it as well (12). Unprotected sexual activity, regardless of if your partner has a vagina or penis, will increase your risk of developing BV (12). This risk increases further if your partner has BV (16).

There is some debate as to whether BV is contagious (12,13). There are no single bacteria responsible for BV that can be passed between people (2,4). However, the introduction of too much “unfriendly” bacteria via a sexual partner can disrupt the natural balance of bacteria in the vagina (2,4). BV is not considered a sexually transmitted infection because it is not exclusively spread through sexual activity (people who have never had sex can still get BV) (12). Also, having sex with someone who has BV or recently had a sexual partner with BV does not guarantee that you will develop it too (12). That being said, unprotected sexual activity (especially among partners where one person has BV) can greatly increase your risk of developing the condition (9,12,16).

The penis does not have the same delicate balance of bacteria as the vagina (9). People with penises cannot develop BV; however, it is not clear whether these folks can spread BV between their sexual partners (9,17). The penis harbours different species of bacteria and this bacterial population varies depending on the person’s current sexual partners (17). Unprotected penetrative sex delivers bacteria (“friendly” and “unfriendly” alike) to the vagina (17). This introduction of bacteria may throw off the balance of bacteria in the vagina, increasing the risk of developing BV (17).

BV occurs more commonly among sexual partners who both have vaginas (3,9,12,16). This is because it is easier for bacteria to be transferred through the direct exchange of vaginal fluids (16). If your partner develops BV, it is important to monitor yourself for symptoms as well. The best way to protect yourself is to use barrier protection when having sex of any kind and to reduce the exchange of vaginal fluids (e.g. cleaning sex toys between uses) (3,9,12). These preventative measures will help reduce your risk of developing BV regardless of if your partner has BV or recently had sex with someone with BV (9,12).

All sources do not specify gender identity. Based on historical representation in scientific literature it is likely these studies only include cisgender people. There is evidence that bacterial vaginosis may occur in neovaginas (surgically constructed vagina), but there is limited research on its management and treatment. The limited research that does exist suggests different methods of treatment may be more effective at managing BV for individuals with neovaginas. This is an important topic for future research to ensure all people with vaginas are receiving the best care possible.

If you have any feedback on this post or any of the content created by missINFORMED, please reach out to us at We appreciate and welcome all feedback as we are committed to the continuous growth and improvement of our organization.

Thank you so much for taking the time to read our article! We hope you appreciated the effort that went into bringing it to you today. As a small not-for-profit, we are heavily reliant on generous donations to helps us stay afloat. Please consider donating to help ensure we can regularly provide health information for young people across Canada. Every donation makes an impact!



  1. Ma B, Forney LJ, Ravel J. Vaginal microbiome: rethinking health and disease. Annual review of microbiology. 2012; 66:371-389. Available from:

  2. Cribby S, Taylor M, Reid G. Vaginal microbiota and the use of probiotics. Interdiscip Perspect Infect Dis. 2008;2008:256490. Available from:

  3. Koumans EH, Sternberg M, Bruce C, McQuillan G, Kendrick J, Sutton M, Markowitz LE. The prevalence of bacterial vaginosis in the United States, 2001–2004; associations with symptoms, sexual behaviors, and reproductive health. Sexually transmitted diseases. 2007 Nov 1;34(11):864-9. Available from:

  4. Han Y, Liu Z, Chen T. Role of Vaginal Microbiota Dysbiosis in Gynecological Diseases and the Potential Interventions. Frontiers in Microbiology. 2021 Jun 18;12:1538. Available from:

  5. Chen X, Lu Y, Chen T, Li R. The female vaginal microbiome in health and bacterial vaginosis. Frontiers in Cellular and Infection Microbiology. 2021 Apr 7;11:631972. doi: 10.3389/fcimb.2021.631972. Available from:

  6. Kairys N, Garg M. Bacterial vaginosis. 2021 Jul 18. Available from: [Accessed 2021 Sep 25].

  7. Ravel J, Gajer P, Abdo Z, Schneider GM, Koenig SS, McCulle SL, Karlebach S, Gorle R, Russell J, Tacket CO, Brotman RM. Vaginal microbiome of reproductive-age women. Proceedings of the National Academy of Sciences. 2011 Mar 15;108(Supplement 1):4680-7. Available from:

  8. Benezra A. Race in the microbiome. Science, Technology, & Human Values. 2020 Sep;45(5):877-902. Available from:

  9. UpToDate. Bacterial vaginosis: Treatment. 2021 Jul 9. Available from: [Accessed 2021 Sep 25]

  10. NIH. Bacterial vaginosis. 2021 May 5. Available from: [Accessed 2021 Sep 25]

  11. Bilardi JE, Walker S, Temple-Smith M, McNair R, Mooney-Somers J, Bellhouse C, Fairley CK, Chen MY, Bradshaw C. The burden of bacterial vaginosis: women's experience of the physical, emotional, sexual and social impact of living with recurrent bacterial vaginosis. PLoS One. 2013; 8(9):e74378. Available from:

  12. Cleveland Clinic. Bacterial vaginosis. 2020 May 5. Available from: [Accessed 2021 Sep 25]

  13. Fethers KA, Fairley CK, Hocking JS, Gurrin LC, Bradshaw CS. Sexual risk factors and bacterial vaginosis: a systematic review and meta-analysis. Clinical Infectious Diseases. 2008 Dec 1;47(11):1426-35. Available from:

  14. Birse KD, Kratzer K, Zuend CF, Mutch S, Noël-Romas L, Lamont A, Abou M, Jalil E, Veloso V, Grinsztejn B, Friedman RK. The neovaginal microbiome of transgender women post-gender reassignment surgery. Microbiome. 2020 Dec;8:1-3. Available from:

  15. Jain A, Bradbeer C. A case of successful management of recurrent bacterial vaginosis of neovagina after male to female gender reassignment surgery. International journal of STD & AIDS. 2007 Feb 1;18(2):140-1. Available from:

  16. Forcey DS, Vodstrcil LA, Hocking JS, Fairley CK, Law M, McNair RP, Bradshaw CS. Factors associated with bacterial vaginosis among women who have sex with women: a systematic review. PloS one. 2015 Dec 16;10(12):e0141905. Available from:

  17. Liu CM, Hungate BA, Tobian AA, Ravel J, Prodger JL, Serwadda D, Kigozi G, Galiwango RM, Nalugoda F, Keim P, Wawer MJ. Penile microbiota and female partner bacterial vaginosis in Rakai, Uganda. MBio. 2015 Jun 16;6(3):e00589-15. Available from:

343 views0 comments


Commenting has been turned off.
bottom of page