Bacterial Vaginosis

Bacterial vaginosis is the most common vaginal condition affecting women of reproductive age worldwide, yet many people with this infection don’t even realize they have it. Understanding what causes this imbalance and how to treat it can help prevent uncomfortable symptoms and reduce the risk of more serious health complications.

Table of contents

• What is Bacterial Vaginosis?
• Signs and Symptoms
• What Causes BV?
• Risk Factors
• How is BV Diagnosed?
• Treatment Options
• Risks and Complications
• Prevention Strategies
• When BV Comes Back

What is Bacterial Vaginosis?

Bacterial vaginosis (BV) is a vaginal infection caused by an overgrowth of certain bacteria that naturally live in the vagina.^[1] Every healthy vagina contains bacteria, and typically these bacteria balance each other out. Sometimes, the “bad” bacteria grow too much and overpower the “good” bacteria, throwing off the balance and leading to bacterial vaginosis.^[1]

More specifically, BV results from a decline in Lactobacillus (healthy vaginal bacteria) and a simultaneous overgrowth of harmful bacteria such as Gardnerella vaginalis, Prevotella species, Mobiluncus species, and other anaerobic bacteria.^[5] These beneficial lactobacilli help maintain a healthy vaginal environment by producing substances that keep the vagina acidic.^[5]

• Vagina

BV is very common. It affects the most common vaginal problem for women ages 15 to 44, with about 35% of people with a vagina experiencing BV at some point.^[1] Global prevalence among women of reproductive age ranges from 23 to 29%.^[5] The rate is higher among Black women, though more research is needed to understand why.^[1]

It’s important to understand that BV is not a sexually transmitted infection (STI), even though it is linked to sexual activity.^[3] While it usually occurs in people who are sexually active, it’s rare for it to occur in people who’ve never had sex.^[1]

Signs and Symptoms

Many people with bacterial vaginosis don’t have any symptoms at all. In fact, up to 84% of people with BV don’t experience noticeable signs.^[1] Half of women with the condition have no symptoms whatsoever.^[3]

When symptoms do occur, they may include:^[1][2][3]

• Thin vaginal discharge that may be off-white, gray, greenish, or yellow in color
• A strong “fishy” smell from the vaginal discharge, especially noticeable after sex
• Vaginal itching or irritation (though this is less common with BV than with yeast infections)
• A burning feeling when urinating

The fishy odor is often described as the hallmark sign of BV and helps distinguish it from other vaginal infections.^[1] The discharge itself is typically thin and either gray or white, rather than thick like cottage cheese (which would suggest a yeast infection).^[4]

Because BV symptoms are similar to other vaginal infections, it’s important to visit a healthcare provider for an accurate diagnosis rather than trying to self-diagnose.^[1]

What Causes BV?

The exact cause of bacterial vaginosis, stemming from the proliferation of harmful bacteria, remains unclear.^[4] While many “good” bacteria are normally found in a healthy vagina, BV results from an imbalance between “good” and “harmful” microorganisms.^[5]

Your vagina is home to multiple types of bacteria, called a microbiome. A change in the balance of these bacteria causes BV.^[1] Specifically, bacterial vaginosis happens when “bad” bacteria (anaerobes) grow more quickly than “good” bacteria (lactobacilli). Too much of one type of bacteria leads to an imbalance.^[1]

Researchers know that anything that changes the natural chemistry of your vagina can affect the bacteria balance.^[1] However, bacterial vaginosis doesn’t spread from person to person in the traditional sense, though sexual activity can increase your risk of getting the infection.^[1]

You cannot get BV from hot tubs, swimming pools, or toilet seats. You also can’t get BV from touching a surface that a person with BV has touched.^[1]

Risk Factors

Anyone with a vagina can get bacterial vaginosis, but certain factors may increase your risk:^[1][3][5]

• Being sexually active
• Having a new sex partner or multiple sex partners
• Having a female sex partner
• Not using condoms or dental dams consistently
• Using an intrauterine device (IUD) for contraception
• Douching (washing the inside of the vagina)
• Using perfumed products, vaginal deodorants, or scented soaps in or around the vagina
• Being pregnant
• Taking antibiotics
• Smoking
• Intravaginal practices, such as inserting herbs or other products into the vagina

Some people may naturally produce too much of the bacteria that causes BV.^[1] Researchers think that sex may change the bacterial environment in your vagina, which makes bacterial overgrowth more likely.^[1]

How is BV Diagnosed?

Healthcare providers will discuss your medical and sexual history and conduct a genital examination to check for the presence of vaginal discharge.^[5] If you have no symptoms, your healthcare provider might find BV during a routine examination or Pap smear.^[8]

To diagnose BV, your provider may:^[2][9]

• Perform a pelvic exam to look at your vagina for signs of infection
• Take a sample of vaginal discharge using a cotton swab
• Test the vaginal fluid sample for “clue cells” (vaginal cells covered in bacteria, which are a sign of BV)
• Test your vaginal pH level (a vaginal pH of 4.5 or higher is a sign of bacterial vaginosis)
• Perform a “whiff test” to check for a fishy odor when a solution is added to the discharge sample

The most commonly used diagnostic test for BV is wet mount microscopy or Gram stain of vaginal fluid, possibly combined with vaginal pH measurement and a sniff test.^[5] A Gram stain that shows a Nugent score of 7-10 is consistent with BV.^[10]

There are also several point-of-care tests available that can provide quick results for BV diagnosis.^[10]

Treatment Options

BV is usually easily treated with antibiotics prescribed by a healthcare provider.^[1] If you have no symptoms, treatment for BV is usually not required, as BV can go away on its own.^[8] However, treatment is important to avoid potential complications, especially if you are pregnant or about to have a medical procedure.^[3]

The most common antibiotic treatments for BV include:^[9]

Metronidazole (Flagyl, Metrogel-Vaginal): This medicine comes as a pill or topical gel. You swallow the pill, but the gel is inserted into the vagina. It’s important to avoid alcohol while using this medicine and for a full day afterward, as it might cause nausea or stomach pain.^[9] The typical dosage is 500 milligrams taken orally twice per day for 7 days, or 5 grams of gel inserted into the vagina once per day for 5 days.^[10]

Clindamycin (Cleocin, Clindesse): This medicine comes as a cream that you insert into the vagina, or as a pill or suppository. The cream and suppositories may weaken latex condoms, so it’s best to avoid sex during treatment and for at least three days after you stop using the medicine.^[9]

Treatment typically lasts 5 to 7 days.^[18] It’s crucial to take all the medicine your provider prescribes, even if your symptoms go away sooner, and don’t have sex until you finish your treatment and your infection clears up.^[6]

Treatment can help reduce the risk of getting other STIs and complications during pregnancy.^[17] Male sex partners of women with BV do not need treatment. However, BV can spread between female sex partners.^[17]

Risks and Complications

BV is a very common condition and does not usually cause serious complications.^[8] Many people with BV do not experience problems. However, if left untreated, BV can lead to more serious health issues:^[5][17]

Increased risk of sexually transmitted infections: After being diagnosed with bacterial vaginosis, patients have an increased risk of acquiring sexually transmitted infections, including HIV, chlamydia, gonorrhea, and herpes (HSV-2).^[4] BV also increases HIV transmission to male sex partners.^[10]

Pregnancy complications: If you have BV while pregnant, your baby is more likely to be born early (premature) or at a low birth weight (less than 5.5 pounds at birth).^[17] BV has been linked with early pregnancy loss (miscarriage), premature labor, and complications such as spontaneous abortion and preterm delivery.^[5][8]

Pelvic inflammatory disease: BV can cause pelvic inflammatory disease (PID), which occurs when bacteria spread from the vagina to the uterus, ovaries, or fallopian tubes.^[5] This can lead to infertility and low fertility.^[19]

Treatment is especially important if you are pregnant or about to have a medical procedure that could allow bacteria into the uterus, such as insertion of an IUD or termination of pregnancy.^[8]

Prevention Strategies

Healthcare providers and scientists do not completely understand how BV spreads or know how best to prevent it.^[17] However, there are several steps you can take to help lower your risk of getting BV or prevent it from returning:^[3][17]

Do:

• Use water and plain, unscented soap to wash your genital area
• Take showers instead of baths
• Use condoms or dental dams correctly every time you have sex
• Limit your number of sex partners
• Practice smoking cessation if you smoke

Don’t:

• Use perfumed soaps, bubble bath, shampoo, or shower gel in the bath
• Use vaginal deodorants, washes, or douches
• Put antiseptic liquids in the bath
• Use strong detergents to wash your underwear
• Douche (wash the inside of the vagina)
• Insert herbs or other products into the vagina

Douching and using perfumed products can increase the risk of developing BV by changing the natural chemistry and pH balance of your vagina.^[6] Hormonal contraception does not increase risk for BV and might actually protect against BV development.^[10]

The best way to prevent BV is to have regular checkups with your gynecologist, since many people don’t have symptoms.^[19]

When BV Comes Back

It’s common for bacterial vaginosis to come back, usually within a few months of treatment.^[3] In fact, 50 to 80% of women experience a BV recurrence within a year of completing antibiotic treatment.^[12] This may be because after antibiotic treatment, beneficial strains of Lactobacillus, such as L. crispatus, do not recolonize the vagina.^[12]

If BV keeps coming back (more than 4 times in a year), you may be given an antibiotic gel that you put in your vagina.^[3] You may need to use this for a few months to help stop bacterial vaginosis from recurring. Your healthcare provider can also help identify if something is triggering your bacterial vaginosis, such as sex or your period.^[3]

For recurring BV, doctors may prescribe longer courses of antibiotics. For example, metronidazole may be prescribed for 10-14 days, or vaginal gel may be used for 10 days, then twice weekly for 3-6 months.^[10]

If you have symptoms that return after you finish the course of your medicine, contact your healthcare provider.^[18]