Bacterial vaginosis (BV) is the most common vaginal infection in women of reproductive age, and the first thing to do about it is get a proper diagnosis and a course of antibiotics. BV clears up with treatment in most cases, but it has a frustrating tendency to come back: 69 to 80% of women experience a recurrence within 12 months. That high return rate means managing BV often involves more than just one round of medication.
What BV Actually Is
Your vagina naturally hosts a community of bacteria, dominated by lactobacilli that produce hydrogen peroxide and keep the environment slightly acidic. BV happens when those protective bacteria get crowded out by other organisms, shifting the balance toward a mix that includes species like Gardnerella vaginalis, Mobiluncus, and Mycoplasma hominis. It’s not a classic infection caused by a single invading germ. It’s more of an ecosystem collapse.
The hallmark symptoms are a thin, grayish-white discharge and a noticeable fishy odor, especially after sex. Some women also experience mild itching or burning during urination. But roughly half of women with BV have no symptoms at all, which is why it sometimes gets picked up incidentally during a routine exam.
How It’s Diagnosed
If you suspect BV, you need a clinical diagnosis rather than self-treating based on symptoms alone. The symptoms overlap with yeast infections and other conditions, and guessing wrong means using the wrong treatment. A healthcare provider can diagnose BV using a few quick in-office tests: checking vaginal pH (which rises above 4.5 in BV), examining a sample of discharge under a microscope for characteristic “clue cells,” and sometimes performing a whiff test where a chemical solution is added to the sample to detect that fishy odor. There are also lab-based scoring systems and newer molecular tests that can confirm the diagnosis from a swab.
First-Line Antibiotic Treatment
The standard treatment is a course of metronidazole or clindamycin, available as oral pills or vaginal gels and creams. Treatment typically lasts five to seven days. Most women notice symptoms improving within a couple of days, but finishing the full course matters for reducing the chance of quick recurrence.
A few practical things to know about treatment: oral metronidazole can cause nausea, and you should avoid alcohol during the course and for at least 24 hours after finishing, because the combination can trigger severe nausea and vomiting. The vaginal gel version tends to cause fewer of those side effects but can sometimes trigger a yeast infection as a secondary issue. Clindamycin cream is another option, though it can weaken latex condoms for several days after use.
Why It Keeps Coming Back
The recurrence rate for BV is genuinely high. Studies tracking women after successful metronidazole treatment found that 69 to 80% had BV return within a year. That number surprises most people, but it reflects how difficult it is to fully restore the vaginal bacterial balance once it’s been disrupted.
Several factors increase recurrence risk. Having a new sexual partner or multiple partners is consistently linked to higher rates, though BV is not classified as a sexually transmitted infection. Douching disrupts vaginal flora and is one of the clearest modifiable risk factors. Smoking is also associated with recurrence, though the exact mechanism isn’t fully understood. Some research suggests that bacteria involved in BV can persist in biofilms on the vaginal lining, essentially hiding from antibiotics and re-emerging after treatment ends.
There’s growing interest in whether treating male sexual partners could reduce recurrence in women. The bacteria associated with BV have been found in the genital tract of male partners, and small trials have explored concurrent partner treatment. This area is still being studied, and partner treatment is not yet part of standard guidelines.
Managing Recurrent BV
If BV keeps returning, your provider may recommend a longer, multi-phase approach. One protocol supported by clinical data involves a seven-day course of oral antibiotics, followed by vaginal boric acid suppositories (600 mg daily) for 21 days, and then a suppressive phase using metronidazole vaginal gel twice a week for four to six months. This layered strategy aims to clear the overgrowth, reset the vaginal pH, and then maintain the environment long enough for healthy bacteria to re-establish.
Boric acid suppositories deserve a specific mention because they’ve become widely available over the counter and are frequently discussed online. They work by lowering vaginal pH, which creates a less hospitable environment for BV-associated bacteria. They are used vaginally only and should never be taken by mouth, as boric acid is toxic if swallowed. They’re also not safe during pregnancy.
Probiotics and Lifestyle Changes
Probiotic supplements marketed for vaginal health have become enormously popular. The two most studied strains are Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14, typically taken orally at doses of at least one billion colony-forming units per day. The theory makes intuitive sense: replenish the good bacteria to crowd out the bad. However, clinical trial results have been mixed. A controlled study testing these specific strains as an add-on to metronidazole found they did not increase the cure rate compared to antibiotics alone. Probiotics are generally safe, but the evidence doesn’t yet support them as a reliable standalone treatment.
Lifestyle changes that can help reduce recurrence are straightforward. Stop douching if you currently do. Use unscented soaps and avoid washing inside the vaginal canal. Wear breathable cotton underwear. Use condoms consistently, which multiple studies have linked to lower BV recurrence rates. These steps won’t cure an active infection, but they support the conditions your vaginal flora needs to stay balanced after treatment.
BV During Pregnancy
BV carries real risks during pregnancy. It affects an estimated 6 to 16% of pregnant women and has been linked to preterm birth, premature rupture of membranes, infection of the amniotic fluid, and postpartum uterine infections. In one 2023 study, women with BV had a preterm birth rate of 22.7% (before 34 weeks) compared to 9% in women without BV. Newborns of affected mothers also faced higher rates of respiratory distress and intensive care admissions.
If you’re pregnant and notice symptoms of BV, or if it’s detected at a prenatal visit, treatment is important. The antibiotic options during pregnancy are similar, though your provider will choose the formulation considered safest for your stage of pregnancy. Boric acid suppositories are not an option during pregnancy.
What to Expect After Treatment
After starting antibiotics, most women feel noticeably better within two to three days, with the discharge and odor resolving first. If symptoms don’t improve after completing the full course, it’s worth going back for re-evaluation, because what seemed like BV might be something else, or you may need a different antibiotic.
Even after successful treatment, it helps to stay aware of your body’s patterns. Many women who deal with recurrent BV learn to recognize the earliest signs, a subtle change in discharge or a faint odor, and can seek treatment before symptoms fully develop. Catching it early each time doesn’t prevent recurrence, but it does make each episode easier to manage.