What Is Bacterial Vaginosis? Symptoms, Causes, and Treatment
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer
Bacterial vaginosis (BV) is a vaginal infection caused by an overgrowth of bacteria that upsets the vaginal microbiome. [1] It is the most common vaginal problem for women ages 15 to 44. [1] Symptoms include fishy-smelling discharge and itching, though up to 84% have none. [1] It is not an STI. [1] A prescription antibiotic treats it, but recurrence is common. [1]
Key takeaways
BV is a bacterial imbalance — “bad” bacteria overgrow the “good” bacteria in your vagina. [1]
It's the most common vaginal problem for women ages 15 to 44; about 35% of people with a vagina get it. [1]
Up to 84% of people with BV have no symptoms; the hallmark sign is fishy-smelling, off-white or gray discharge. [1]
BV is not an STD or STI and doesn't spread through contact — hot tubs, pools, and toilet seats don't cause it. [1]
Only a healthcare provider can diagnose it; there are no over-the-counter treatments. [1]
Prescription antibiotics (metronidazole or clindamycin) usually clear it in up to seven days — finish the full course. [1]
Untreated BV can raise the risk of STIs, pelvic inflammatory disease, and pregnancy complications. [1]
What the research says
BV is one of the most common vaginal conditions worldwide. Estimates vary by study, but a meta-analysis of general-population studies found that BV prevalence among reproductive-aged women ranged from 23% to 29% across world regions (23% in Europe and Central Asia, 27% in North America, 29% in South Asia). In North America, prevalence was higher in Black (33%) and Hispanic (31%) women than in white women (23%). The authors estimated that treating symptomatic BV costs about US $4.8 billion a year worldwide. (Peebles et al., Sex Transm Dis, 2019) [2]
BV often comes back after treatment. In a 12-month study that enrolled 139 women with symptomatic BV treated with a 7-day course of oral metronidazole, 58% (95% CI 49%–66%) had a recurrence of BV, and 69% had a recurrence of abnormal vaginal flora, by 12 months. A past history of BV, a regular sex partner, and female sex partners were linked to recurrence, while hormonal contraception was linked to fewer recurrences. (Bradshaw et al., J Infect Dis, 2006) [3]
BV during pregnancy is linked to preterm delivery and miscarriage. A meta-analysis of 32 studies covering 30,518 patients found that BV more than doubled the risk of preterm delivery in women without symptoms (odds ratio 2.16, 95% CI 1.56–3.00). In those women it also raised the odds of late miscarriage (odds ratio 6.32) and maternal infection (odds ratio 2.53). (Leitich & Kiss, Best Pract Res Clin Obstet Gynaecol, 2007) [4]
What Is Bacterial Vaginosis?
Bacterial vaginosis (BV) is a vaginal infection caused by an overgrowth of bacteria. [1] Every healthy vagina contains bacteria — these are part of a natural ecosystem called a microbiome, and typically these bacteria balance each other out. Sometimes, the “bad” bacteria grow too much and overpower the “good” bacteria, throwing off the balance in your vagina and leading to bacterial vaginosis. [1]
BV may cause your vaginal discharge to have a “fishy” odor, and it can cause vaginal irritation in some people. Others may not have any symptoms at all. [1]
How Common Is Bacterial Vaginosis?
Bacterial vaginosis is the most common vaginal problem for women ages 15 to 44. [1] About 35% of people with a vagina will get BV, and the rate is higher for Black women. [1]
Who Can Get BV?
Anyone with a vagina can get bacterial vaginosis. It usually occurs in people who are sexually active, and it's rare for it to occur in people who've never had sex. [1] Some people may naturally produce too much of the bacteria that causes BV. [1]
What Are the Symptoms of Bacterial Vaginosis?
Up to 84% of people with bacterial vaginosis don't have symptoms. [1] If you do, you may notice:
Symptom | Description |
Off-white, gray, or greenish discharge | The discharge may take on an unusual color or consistency |
Fishy-smelling discharge | Often most noticeable after sex |
Vaginal itching or irritation | Some people experience discomfort or itching |
Burning when you pee | A stinging sensation during urination |
Because BV symptoms are similar to other vaginal infections, it's important to see a healthcare provider to determine whether what you have is BV or another infection. [1]
How Do You Get Bacterial Vaginosis?
Your vagina is home to multiple types of bacteria (called a microbiome), and a change in the balance of those bacteria causes BV. Specifically, bacterial vaginosis happens when “bad” bacteria (anaerobes) grow more quickly than “good” bacteria (lactobacilli). [1] Too much of one type of bacteria leads to an imbalance.
Researchers know that anything that changes the natural chemistry of your vagina can affect the bacteria there — which is why certain activities like douching or unprotected sex can lead to BV. [1] You can't get BV from hot tubs, swimming pools, or toilet seats, and you can't get it from touching a surface a person with BV has touched. [1]
Who is at higher risk?
Risk factor | Why it raises risk |
Pregnancy | About 25% of pregnant women get BV, due to the hormonal changes of pregnancy |
Not using condoms or dental dams | Research indicates sexual activity is associated with BV |
Having an intrauterine device (IUD) | IUDs are linked to a higher rate of BV |
Multiple sex partners | Research shows you're more likely to get BV with multiple partners |
A new sex partner | A change in sexual partners is a known risk factor |
Douching | Douching changes the natural balance of bacteria in your vagina |
Taking antibiotics | Antibiotics can disturb the healthy bacteria that fight off bad bacteria |
Is Bacterial Vaginosis Contagious?
No. Bacterial vaginosis doesn't spread from person to person, but sexual activity can increase your risk of getting the infection. [1]
Is BV a Sexually Transmitted Disease?
Bacterial vaginosis isn't sexually transmitted, but it's linked to sexual activity. [1] Researchers think that sex may change the bacterial environment in your vagina, making bacterial overgrowth more likely. Men don't need treatment for BV, but they can spread the bacteria that causes it — so it's possible to get BV from a female partner and pass it to another female partner. [1]
BV vs. Yeast Infection: What's the Difference?
Both bacterial vaginosis and yeast infections are vaginal infections that increase amounts of discharge. Here's how to tell them apart:
Factor | Bacterial vaginosis | Yeast infection |
Discharge | Hallmark sign is discharge with a “fishy” smell | Doesn't usually have a strong smell; may look like cottage cheese |
Vaginal irritation | Typically doesn't cause irritation or itchiness | Usually causes irritation and itchiness |
Treatment | Requires a healthcare provider for prescription antibiotics | Can be treated with over-the-counter (OTC) medications |
Since the two look similar, self-diagnosing can be misleading — an accurate diagnosis from a provider is the safest route.
How Is Bacterial Vaginosis Diagnosed?
Only a healthcare provider can diagnose bacterial vaginosis. [1] At your appointment, your provider will ask about your medical history, including any past vaginal infections or sexually transmitted infections. They may also:
Diagnostic step | What happens |
Medical history review | Questions about past vaginal infections and STIs |
Pelvic exam | Your provider places gloved fingers inside your vagina to look for signs of infection, like increased or foul-smelling white or gray discharge |
Discharge sample | A speculum is inserted and a swab collects fluid from your vagina, which is sent to a lab to identify the types of bacteria present |
The fluid sample can undergo several types of tests:
Test | How it works |
Wet mount | Your vaginal discharge is examined on a glass slide under a microscope |
Whiff test | Your provider smells your vaginal discharge for a fish-like smell |
Vaginal pH | Measures how acidic your discharge is; a higher pH may indicate BV |
How Is Bacterial Vaginosis Treated?
Your healthcare provider will prescribe antibiotics, typically metronidazole or clindamycin. [1] These medications come as a gel or cream you insert into your vagina, or as pills you take by mouth. It's important to finish the antibiotic exactly as prescribed — stopping early because your symptoms go away increases your risk of getting BV again. [1]
There are no over-the-counter products to treat BV. Avoid using douches or products meant for yeast infections, which could make BV worse. [1] See a healthcare provider for treatment.
How Long Does BV Last?
Most of the time, one round of antibiotics — taken for up to seven days — eliminates the infection. About 10% to 15% of people need another round of treatment. [1] Some cases resolve on their own without medication, but if you have symptoms, you should seek medical care: having BV makes you prone to sexually transmitted infections and can affect pregnancy. [1]
Can You Get Bacterial Vaginosis Multiple Times?
Yes. Up to 80% of people get bacterial vaginosis again in their lifetime. [1] If BV keeps coming back, it may help to talk openly with your partner. In some cases, working with a certified sex therapist can improve communication, address concerns about intimacy, and support healthy sexual habits that may reduce recurrence. [1]
Can Bacterial Vaginosis Lead to Complications?
BV doesn't typically cause serious complications on its own. But if left untreated, it could lead to:
Complication | What it means |
Pregnancy complications | BV during pregnancy may lead to premature birth or a baby weighing less than average (low birth weight) |
Sexually transmitted infections | BV increases your risk for STIs like chlamydia and gonorrhea; if you have HIV and develop BV, you're at higher risk for passing HIV to your partner |
BV can cause PID, an infection of your reproductive organs; untreated, PID can lead to difficulties getting pregnant |
What About BV During Pregnancy?
If you have BV and you're pregnant, your provider can prescribe medication that's safe to use during pregnancy. You should get treated for the infection whether or not you have symptoms, because BV can cause pregnancy complications such as premature birth or low birth weight. [1]
How Can I Lower My Risk of BV?
You can't completely prevent bacterial vaginosis. However, these precautions could reduce your risk:
Prevention step | How it helps |
Avoid douching | Douching changes the natural balance of bacteria; practice healthy vaginal and vulvar care instead |
Avoid vaginal contact with anything that has touched your anus | Toilet paper and sex toys could transfer bacteria from your anus to your vagina; clean sex toys after every use |
Limit your number of sex partners | Research shows you're more likely to get BV with multiple partners |
Use latex condoms or dental dams | Although it's unclear why, research indicates sexual activity is associated with BV |
Wear cotton or cotton-lined underwear | Bacteria thrive in moist environments; cotton helps wick away moisture |
If BV keeps recurring and involves a partner, between-women couples can protect themselves by covering sex toys with a condom (replacing it each time the toy is shared) and using a dental dam during oral sex. If one partner has BV, let the other know so they can get treatment too.
When Should I Call My Healthcare Provider?
Call your provider if you have discharge that changes color or consistency, discharge that smells different than usual, or vaginal itching, burning, swelling, or soreness. Although BV is a mild infection, it can make you vulnerable to more serious conditions [1] — so don't put off seeing a healthcare provider if you notice anything unusual about your vaginal discharge.
Conclusion
Bacterial vaginosis is the most common vaginal problem for women ages 15 to 44 — and about 35% of people with a vagina will experience it at some point. [1] The root cause isn't an infection you catch from someone else; it's an internal imbalance, where “bad” bacteria (anaerobes) outgrow the “good” bacteria (lactobacilli) that make up your vaginal microbiome. [1] Douching, hormonal changes, an IUD, new or multiple partners, and taking antibiotics can all tip that balance. [1]
The hallmark sign is an off-white, gray, or greenish discharge with a “fishy” odor, often strongest after sex — but since up to 84% of people with BV have no symptoms at all, and BV mimics other infections like yeast infections, a provider's diagnosis is the only reliable path. [1] Treatment is always a prescription antibiotic, typically metronidazole or clindamycin, as a gel, cream, or pill. [1] There are no over-the-counter treatments, and finishing the full course matters, because stopping early raises the odds of recurrence — and recurrence is common, affecting up to 80% of people over their lifetime. [1]
Left untreated, BV can raise the risk of STIs, pelvic inflammatory disease, and pregnancy complications like premature birth [1], so it's worth addressing promptly even though it usually feels mild.
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Frequently Asked Questions
What causes bacterial vaginosis?
BV happens when “bad” bacteria (anaerobes) grow more quickly than “good” bacteria (lactobacilli) in your vagina's microbiome. [1] Anything that changes the natural chemistry of your vagina — douching, unprotected sex, hormonal changes — can affect that balance. [1]
Who is most likely to get BV?
Anyone with a vagina can get it. It usually occurs in people who are sexually active and is rare in people who've never had sex. [1] About 25% of pregnant women get BV due to hormonal changes, and the rate is higher for Black women. [1]
What are the symptoms?
Up to 84% of people have no symptoms. [1] Common symptoms include off-white, gray, or greenish discharge, fishy-smelling discharge (especially after sex), vaginal itching or irritation, and burning when you pee. [1]
Is BV contagious?
No. BV doesn't spread from person to person, and you can't get it from hot tubs, swimming pools, toilet seats, or touched surfaces. However, sexual activity can increase your risk. [1]
Is BV a sexually transmitted disease?
No. BV isn't sexually transmitted, but it's linked to sexual activity. Researchers think sex may change the bacterial environment in your vagina, making overgrowth more likely. [1] Men can carry and spread the bacteria but don't need treatment. [1]
How do I know if it's BV or a yeast infection?
BV discharge typically has a fishy smell, while yeast infection discharge looks like cottage cheese and usually doesn't smell strong. [1] Yeast infections usually cause itching and can be treated with OTC products; BV typically doesn't cause irritation or itchiness and requires prescription antibiotics from a provider. [1]
How is BV diagnosed?
Only a healthcare provider can diagnose it. Diagnosis involves a medical history review, a pelvic exam, and a swab sample of vaginal discharge tested through a wet mount (microscope exam), a whiff test (smelling for a fish-like odor), and a vaginal pH test (higher pH may indicate BV). [1]
How is BV treated?
Providers prescribe antibiotics — typically metronidazole or clindamycin — as a vaginal gel or cream, or as oral pills. [1] There are no over-the-counter products that treat BV, and douching or yeast-infection products can make it worse. [1]
Can BV go away on its own?
Some cases resolve without medication, but if you have symptoms you should seek medical care. Having BV makes you prone to STIs and can affect pregnancy. [1]
How long does treatment take?
Most of the time, one round of antibiotics taken for up to seven days eliminates the infection. About 10% to 15% of people need another round. [1]
Can BV come back?
Yes. Up to 80% of people get BV again in their lifetime. [1] Recurrence can be helped by talking openly with your partner and, in some cases, working with a certified sex therapist. [1]
Should BV be treated during pregnancy?
Yes. Your provider can prescribe medication that's safe during pregnancy, and you should be treated whether or not you have symptoms — BV can cause premature birth or low birth weight. [1]
Can BV cause complications if left untreated?
Yes. Untreated BV can lead to pregnancy complications (premature birth, low birth weight), increased risk of STIs like chlamydia and gonorrhea (and passing HIV to a partner), and pelvic inflammatory disease, which can make it harder to get pregnant. [1]
How can I lower my risk?
Avoid douching, wear cotton or cotton-lined underwear, limit your number of sex partners, use latex condoms or dental dams, avoid vaginal contact with anything that has touched your anus (and clean sex toys after every use), and see a provider promptly for any unusual discharge. [1]
Related Reading
Pelvic Exam: What to Expect, How to Prepare and What It Checks explains what happens during a pelvic exam and what it can find.
Bacterial Vaginosis (BV) Test: How It's Done, Types and What Results Mean explains how BV is tested and what results mean.
References
Cleveland Clinic. Bacterial Vaginosis. Cleveland Clinic Health Library. Last updated February 6, 2023. Accessed October 15, 2026. https://my.clevelandclinic.org/health/diseases/3963-bacterial-vaginosis
Peebles K, Velloza J, Balkus JE, et al. High global burden and costs of bacterial vaginosis: a systematic review and meta-analysis. Sex Transm Dis. 2019;46(5):304-311. PMID: 30624309. https://doi.org/10.1097/OLQ.0000000000000972
Bradshaw CS, Morton AN, Hocking J, et al. High recurrence rates of bacterial vaginosis over the course of 12 months after oral metronidazole therapy and factors associated with recurrence. J Infect Dis. 2006;193(11):1478-1486. PMID: 16652274. https://doi.org/10.1086/503780
Leitich H, Kiss H. Asymptomatic bacterial vaginosis and intermediate flora as risk factors for adverse pregnancy outcome. Best Pract Res Clin Obstet Gynaecol. 2007;21(3):375-390. PMID: 17241817. https://doi.org/10.1016/j.bpobgyn.2006.12.005
Medical disclaimer
The information provided in this article is for educational purposes only and is not intended as medical advice. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. If you notice unusual vaginal discharge, a new odor, itching, burning, or swelling, especially during pregnancy, contact a healthcare provider promptly.
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