Roughly 1 in 3 women in the United States between ages 14 and 49 has bacterial vaginosis at any given time, making it the most common vaginal infection in reproductive-age women. BV is often confused with a yeast infection because both produce discharge and discomfort, but the underlying cause is entirely different and the treatment is too. Recurrent BV affects more than half of women within a year of treatment, which is why understanding the condition matters as much as treating it.
What BV Is
Bacterial vaginosis is a shift in the vaginal microbiome away from protective lactobacilli (which produce hydrogen peroxide and lactic acid to keep the pH low) and toward a polymicrobial overgrowth of anaerobic bacteria, most notably Gardnerella vaginalis, Atopobium vaginae, and various Mobiluncus species. The result is a higher vaginal pH and the characteristic discharge and odor.
CDC fact sheets emphasize that BV is not strictly a sexually transmitted infection, but sexual activity is a major risk factor and the bacterial profile of new sexual partners can shift the vaginal flora. Untreated BV increases the risk of acquiring HIV, herpes, gonorrhea, and chlamydia, and during pregnancy raises the risk of preterm birth and other complications.
Causes and Risk Factors
BV develops when the lactobacillus-dominated vaginal flora is disrupted. Common triggers include new or multiple sexual partners, female sexual partners specifically, douching, intrauterine device use (with mixed evidence), antibiotic exposure, and hormonal changes. Smoking is associated with a higher risk and lower cure rates. Black women have a higher prevalence than white or Asian women, though the reasons are multifactorial and not fully understood.
Importantly, women who have never had vaginal sex can still develop BV, which is why “STI” is not the right framework. The condition reflects the ecology of the vaginal microbiome more than transmission of a specific pathogen. Coexistence with yeast infections is common, and women sometimes treat the wrong condition first.
Symptoms
The hallmark symptom is a thin, gray-white or yellow-white discharge with a strong fishy odor, particularly noticeable after sexual intercourse or during menses. The odor can be intense and is often the symptom that drives women to seek care. Vaginal pH rises above 4.5 (compared to a normal 3.8 to 4.5), and lactobacilli decline.
BV does not typically cause significant itching or burning. Those symptoms are more consistent with yeast infection or other causes. Up to 50 to 75 percent of women with BV have no symptoms at all, which complicates screening but also means BV often does not require treatment unless symptoms are present, the woman is pregnant, or she is undergoing certain gynecologic procedures.
Diagnosis
Diagnosis uses Amsel criteria (presence of 3 of 4: thin homogeneous discharge, vaginal pH greater than 4.5, positive whiff test with potassium hydroxide producing fishy odor, and presence of clue cells on microscopy) or Nugent score (a Gram stain-based score of 7 to 10 on a 0-to-10 scale). Both methods are accurate when performed correctly.
Newer DNA-based tests (such as BD Affirm and Aptima panels) detect BV-associated organisms simultaneously with yeast and trichomoniasis and are increasingly used in clinical practice. Self-diagnosis based on symptoms alone is unreliable, particularly because BV and yeast infection can coexist and produce overlapping symptoms.
Treatment
First-line treatment per CDC 2021 STI treatment guidelines is metronidazole 500 mg orally twice daily for 7 days, intravaginal metronidazole 0.75 percent gel once daily for 5 days, or intravaginal clindamycin 2 percent cream once daily for 7 days. All three regimens have similar cure rates of 70 to 80 percent at one month.
Alternative regimens include tinidazole, secnidazole (a single oral 2-gram dose), and oral clindamycin. Secnidazole’s single-dose convenience is appealing but cost is meaningfully higher. Avoiding alcohol during oral metronidazole or tinidazole is recommended due to a disulfiram-like reaction, though recent evidence suggests this risk has been overstated.
Recurrent BV is treated more aggressively. Common strategies include twice-weekly metronidazole gel suppression for 4 to 6 months, longer initial courses, and adjunctive boric acid (600 mg vaginal suppository for 14 to 21 days) followed by suppressive metronidazole gel. Newer approaches investigate vaginal microbiome transplant and lactobacillus-based products, with mixed but evolving evidence.
BV in Pregnancy
Symptomatic BV during pregnancy is treated to relieve symptoms and reduce the risk of preterm delivery, late miscarriage, and postpartum endometritis. Oral metronidazole and oral clindamycin are both safe in pregnancy. Routine screening of asymptomatic pregnant women without prior preterm birth is not recommended by the USPSTF, though some guidelines suggest screening high-risk patients.
Prevention and Recurrence
Recurrence is the central challenge. More than half of women treated for BV experience recurrence within 12 months. Prevention focuses on supporting healthy vaginal flora: avoiding douching, limiting unnecessary antibiotic exposure, using condoms (which reduce the bacterial transfer that can disrupt flora), and avoiding scented vaginal products.
Probiotics, particularly Lactobacillus crispatus and Lactobacillus rhamnosus strains, have modest evidence for reducing recurrence. Vaginal probiotic capsules show more promise than oral preparations, though commercial products vary widely in quality. Boric acid suppositories used adjunctively or as maintenance have a long history of off-label use with reasonable safety. The broader women’s health conditions overview ties together the multiple approaches to vaginal health.
For women in same-sex female relationships, treating both partners simultaneously may reduce recurrence, though evidence is still emerging. For women with male partners, partner treatment has historically not been recommended, but a 2024 randomized trial in pregnant and non-pregnant women suggested that male partner treatment significantly reduced recurrence, prompting some specialists to reconsider this practice.
When to See a Doctor
Schedule a visit if you have new or unusual vaginal discharge, a fishy odor (especially after intercourse), pelvic pain, fever, or symptoms that fail to improve with OTC remedies. New onset of symptoms during pregnancy warrants evaluation, since untreated BV during pregnancy is associated with worse outcomes. Recurrent or refractory BV needs a more targeted approach including microscopy and possibly molecular testing.
When to seek emergency care: Call 911 or go to the nearest emergency room if you experience high fever, severe pelvic pain, signs of pelvic inflammatory disease (severe pain with deep palpation, cervical motion tenderness, fever), or rapid progression of symptoms. BV alone is rarely an emergency, but BV can coexist with more serious infections like PID, which require urgent care.
Frequently Asked Questions
Can BV go away on its own?
Sometimes, yes, particularly in mild cases. However, untreated BV raises the risk of acquiring STIs and during pregnancy can lead to complications. Treatment is recommended for symptomatic women and for those with specific risk factors regardless of symptoms.
Is BV a sexually transmitted infection?
Not in the strict sense. BV is a disturbance of the vaginal microbiome, but sexual activity (especially with new or multiple partners, including female partners) is a strong risk factor. Condom use reduces BV recurrence in studies.
Why do I keep getting BV?
Common contributors to recurrence include douching, sexual practices that disrupt flora, hormonal changes, smoking, and underlying differences in vaginal microbiome composition. Suppressive treatment, probiotics, and addressing modifiable triggers reduce recurrence.
Can I treat BV with home remedies?
OTC products marketed for BV (yogurt, garlic, vinegar douches, hydrogen peroxide rinses) lack rigorous evidence and can disrupt flora further. Boric acid suppositories have some support as an adjunct under medical guidance. Antibiotic treatment remains the standard.
The Practical Takeaway
Bacterial vaginosis is common, often misidentified as a yeast infection, and frequently recurrent. Standard antibiotic regimens cure most initial cases, but recurrence within a year affects most women, making prevention and microbiome-supportive practices central to long-term management. Distinguishing BV from yeast infection or trichomoniasis is essential because the treatments do not overlap. If symptoms keep returning despite treatment, ask about cultures, suppressive regimens, and adjunctive therapies, since BV management has moved well beyond a single 7-day course of antibiotics.