What Is Bacterial Vaginosis?

Bacterial vaginosis (BV) is a common vaginal infection related to an overgrowth of bacteria that’s naturally found in your vagina. Bacterial vaginosis can make your vagina itch or burn, which can also be symptoms or other conditions. But if you think you have BV—or experience any unusual vaginal itching, discharge, or odor—always see a healthcare provider. 

Most people with BV won't show any symptoms, which can make it harder to diagnose. Here’s all you need to know about BV, plus how to treat it. 

What Is Bacterial Vaginosis?

BV happens when there's an overgrowth of bacteria that’s normally present in the vagina. When this happens, your entire vaginal ecosystem is thrown out of whack. Your vagina becomes more susceptible to bacterial and yeast infections, and sexually transmitted infections (STIs).  

BV is the most common vaginal condition in people ages 15-44. Nearly one in three people with vaginas will experience BV in their lifetime, and one in two of these people will also have recurrent infections within six months of treatment. 

What Causes Bacterial Vaginosis?

Researchers don’t know what causes BV, but it has to do with disrupting the balance of “good” and “harmful” bacteria in your vagina. Under normal circumstances, a healthy vagina contains a balance of both good (namely, lactobacilli) and bad bacteria. 

The "good" lactic acid-producing bacteria keep the vagina's environment mostly acidic, which isn't an ideal atmosphere for "bad" bacteria to multiply and lead to infections. But when more bad bacteria is introduced to the vagina—or good bacteria gets wiped out—harmful bacteria can take over and cause infections like BV. 

Risk Factors

BV is not considered an STI, however, the condition is more common in people who are sexually active. Certain behaviors can also throw off your vaginal flora and increase your risk of getting BV:

• Having multiple or new sex partners
• Not using condoms or other barrier methods
• Douching

According to the CDC, people of color are also disproportionately affected by BV. BV can also spread between sexual partners if both partners have a vagina.

Symptoms of Bacterial Vaginosis

Only 16% of people with BV have symptoms. Here are some signs and symptoms of BV:

• Itching or burning inside the vagina: A BV infection can lead to uncomfortable inflammation. Your vagina may itch as the infection activates your itch receptors. You may also experience painful burning as the infection irritates your vaginal tissue.
• Itching around the outside of the vagina: Although less common, you might also experience itching outside of your vaginal opening.
• Thin, off-white or gray discharge: Unusual vaginal discharge is one of the most common characteristics of BV. The off-white or gray color is likely from the “bad” bacteria overgrowth (Gardnerella vaginalis) that grows in small gray patches.
• Fishy odor, especially after sex: People with BV tend to have high levels of trimethylamine in their vaginal discharge, which is a chemical compound that makes body fluids smell like dead fish.
• Burning while peeing: The bacteria that cause BV can also infect your urinary tract, giving you that on-fire feeling while you pee. A decrease in good bacteria can increase your risk of having a urinary tract infection (UTI) and BV simultaneously.

How Bacterial Vaginosis Is Diagnosed

BV is typically diagnosed with a physical exam and a swab test. During your exam, your healthcare provider will examine your vagina for abnormal vaginal discharge and odor. They will also ask questions about your symptoms and sexual history to determine the probability of having a BV infection. 

During the swab test, a swab is inserted into your vagina to collect vaginal specimens, which are viewed under a microscope for clue cells, which are cells covered with rod-shaped bacteria that indicate a BV infection. 

If you show signs of BV discharge and odor during your exam, your healthcare provider might instead use a pH strip to test the acidity of your vaginal fluid. A level of 4.5 or higher indicates a less acidic environment and the likelihood of BV. 

Other healthcare providers may also lab-test your vaginal fluid to detect the specific bacteria species causing your BV infection. 

Treatment for Bacterial Vaginosis

After a confirmed BV diagnosis, your healthcare provider will prescribe antibiotics to treat the infection. Using an over-the-counter (OTC) triple antibiotic ointment or some home treatments in your vagina isn’t a good idea, or an approved method to effectively treat BV. 

It’s also important to finish your treatment, even if your symptoms subside, to ensure the infection is gone. You’ll need to avoid having sex until your treatment is over. Not treating BV puts you at higher risk of getting HIV, giving birth too early if you’re pregnant, or getting other STDs like chlamydia and gonorrhea.  

Here are some ways your healthcare provider may treat BV.

Oral Antibiotics

Metronidazole (Flagyl) or clindamycin (Cleocin) pills are taken twice a day for one week. For shorter regimens (in higher dosages), your provider may prescribe tinidazole (Tindamax) once a day for five days or once a day for two days. Some providers also recommend secnidazole (Solosec), a single dose that comes in the form of granules or small tabs that you take orally. 

These medications may all cause side effects like digestive issues and nausea, and clindamycin can cause vaginal yeast infections. Tinidazole and secnidazole are also not recommended if you’re pregnant.

Intravaginal Gel or Cream Antibiotics

Metronidazole and clindamycin are also available in gel or cream forms you insert into your vagina. You typically use these daily for seven days. Some formulations are also single-dose. These gels or creams have fewer side effects than oral antibiotics but can cause vaginal irritation. 

Antibiotics and Boric Acid Suppositories

While not as common, some healthcare providers may recommend a combination of antibiotics and boric acid suppositories to treat or prevent recurrent BV infections. 

However, there’s no solid evidence that taking boric acid alone will treat BV. Boric acid suppositories may also cause mild vaginal irritation and are not safe to use if you’re pregnant.

How to Prevent Bacterial Vaginosis

Despite not knowing the exact cause of BV, there are preventative measures you can take to decrease your odds of contracting the infection. Although BV may not be considered an STI, sexual activity is one of the most common risk factors.

To help prevent future BV infections, the CDC suggests keeping your number of sexual partners to a minimum, avoiding douching products, and using condoms (and other preventative barriers) to avoid swapping bacteria.