What Causes BV? Bacterial Vaginosis Causes, Risk Factors and Myths
Written by Naurah Gaspard, DNP, FNP-C, FNP-BC · Medically reviewed by Cherlie Joseph, MSN, FNP-BC · Updated November 2026
BV is caused by an imbalance of vaginal bacteria: protective lactobacilli decrease and other bacteria, such as Gardnerella, overgrow. Douching, a new sex partner, multiple partners and sex without condoms raise the risk, while poor hygiene, toilet seats and swimming pools do not cause BV.
In this guide
What is happening in your body
A healthy vagina is usually dominated by Lactobacillus bacteria. They make lactic acid, which keeps the vaginal pH low (acidic, roughly 3.8 to 4.5) and keeps other bacteria in check. In bacterial vaginosis, lactobacilli drop and a mix of other bacteria, including Gardnerella, Prevotella and others, takes over. The pH rises above 4.5, and those bacteria release compounds called amines that cause the classic fishy odor.
BV is not caused by one germ you "catch" the way you catch the flu. It is a shift in the whole community of bacteria. That is why it can appear without an obvious trigger, and why it can come back after treatment.
Proven risk factors
The CDC lists these as linked with BV:
| Risk factor | Why it matters |
|---|---|
| Douching | Washes out lactobacilli and raises pH; also linked with BV coming back |
| A new sex partner or multiple partners | Introduces new bacteria; BV bacteria can live on a partner's genital skin |
| Sex without condoms | Semen is alkaline and temporarily raises vaginal pH |
| Female sex partners | BV can pass between women who have sex with women |
| Copper IUD | Associated with higher BV rates in studies |
| Menstrual period | Blood raises pH, so BV is more common around periods |
Hormonal birth control does not raise BV risk and may even be protective, according to the CDC. Smoking has also been linked with BV in research.
Think it might be BV?
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Start a BV visit →Myths about what causes BV
- "BV means you are not clean." False. Over-washing and scented products are more likely to cause BV than under-washing.
- "You can get it from toilet seats, pools or bedding." There is no evidence for this.
- "Only people who have sex get BV." BV is more common in sexually active people, but it can happen in people who have never had sex.
- "BV is just a yeast infection." They are different conditions with different treatments. Yeast usually causes itching and thick white discharge; BV usually causes thin gray-white discharge and odor with little itching.
- "Vitamin D supplements prevent BV." The CDC does not recommend high-dose vitamin D to prevent BV recurrence.
Why BV is worth treating
Many people with BV have no symptoms at all. When symptoms do appear, they include a thin gray or white discharge and a fishy odor that is often stronger after sex. Even mild BV matters because it is linked with a higher chance of getting STIs, including HIV, gonorrhea, chlamydia and herpes, and with pregnancy complications such as preterm birth. Treatment is usually a short course of metronidazole or clindamycin, either as pills or a vaginal gel or cream.
How to lower your risk
- Clean the vulva with water or a gentle unscented soap, and skip douches, sprays and vaginal "washes."
- Use condoms with new partners and limit the number of partners.
- Wash sex toys between uses, and use a new condom on shared toys.
- Wear breathable cotton underwear and change out of wet clothes soon.
- If BV keeps coming back, ask about longer suppressive treatment and whether partner treatment makes sense for you.
Get in-person care or call 911 if you have:
- Fever, chills, or pain in your pelvis or lower belly
- Unusual discharge or bleeding while pregnant
- Sores, blisters or severe swelling in the genital area
- Severe pain or vomiting that keeps you from drinking fluids
Frequently asked questions
Can stress cause BV?
Research suggests stress may affect vaginal bacteria, but it has not been proven to directly cause BV. The best-established triggers are douching, new or multiple partners and sex without condoms.
Can my partner give me BV?
BV is not an STI, but sex does play a role. BV-associated bacteria can live on a male partner's penis, and a 2025 study found that treating male partners lowered how often BV came back.
Can BV go away on its own?
Sometimes mild BV clears without treatment, but many cases persist. Because BV raises the risk of STIs and pregnancy complications, it is worth getting treated if you have symptoms.
Sources
- CDC: Bacterial Vaginosis, STI Treatment Guidelines
- MedlinePlus: Vaginitis
- Cleveland Clinic: Vaginal Discharge
Keep reading
- BV keeps coming back? How to break the cycle
- BV treatment with metronidazole
- Yeast infection vs BV
- Browse all conditions and treatments A to Z
Think it might be BV?
$79 visit, no appointment needed. Adults 18+ in FL, NM, OR and WA.
Start a BV visit →
Naurah Gaspard, DNP, FNP-C, FNP-BC
Board-certified family nurse practitioner licensed in Florida, New Mexico, Oregon and Washington, caring for adults online at OurTopClinic. Meet our providers.
This article is for general education and is not a substitute for medical advice. Treatment, including any prescription, is decided by a licensed provider after reviewing your health history. OurTopClinic is not for emergencies; if you have a medical emergency, call 911. OurTopClinic serves adults located in Florida, New Mexico, Oregon and Washington. Learn more at ourtopclinic.com.
