What Causes Bv And Why Does It Keep Coming Back?

Bacterial vaginosis is not caused by poor hygiene or anything you did wrong. It happens when the normal balance of bacteria in the vagina shifts, allowing certain bacteria to overgrow while protective bacteria like lactobacillus drop too low. The reason it keeps coming back for many women is that standard antibiotic treatment often clears the symptoms without fully restoring that protective bacterial balance, leaving the door open for recurrence within weeks or months.

What Exactly Is Bacterial Vaginosis?

Bacterial vaginosis, or BV, is the most common vaginal condition in women ages 15 to 44. It is not a sexually transmitted infection, though sexual activity can influence it. BV is a disruption of the vaginal microbiome. Think of it like a garden where the good plants keep the weeds in check. When the good plants die off, the weeds take over.

In a healthy vagina, lactobacillus bacteria dominate. They produce lactic acid and hydrogen peroxide, which keep the pH low and unfriendly to other bacteria. In BV, lactobacillus levels drop, and anaerobic bacteria like Gardnerella vaginalis, Atopobium, and Prevotella multiply rapidly. This shift causes the thin, grayish discharge and fishy odor that define BV.

Research shows that about 30 percent of women with BV have no symptoms at all. But for those who do, the symptoms can be frustrating and embarrassing. The real problem is not just having BV once. It is the fact that up to 50 percent of women will have a recurrence within 12 months of treatment.

What Causes BV To Develop In The First Place?

The short answer is that the protective lactobacillus bacteria get displaced. The longer answer involves several known triggers. Douching is one of the strongest. Studies have found that women who douche regularly are significantly more likely to develop BV. Douching washes away the good bacteria and alters the vaginal pH, creating an environment where harmful bacteria thrive.

Sexual activity also plays a role. Having a new sexual partner or multiple partners increases the risk. Semen has a higher pH than the vagina, and it can temporarily disrupt the balance. However, BV can occur in women who have never had sex. It is not an STI, and treating male partners with antibiotics does not reduce recurrence rates.

Other factors include hormonal changes, especially drops in estrogen. This is why BV is more common during perimenopause and menopause. Antibiotic use can also trigger BV by killing off lactobacillus along with the bacteria they target. Even using certain soaps, bubble baths, or scented menstrual products can irritate the vaginal lining and disturb the microbiome.

One non-obvious insight: current research suggests that genetics may influence who gets recurrent BV. Some women naturally have a less robust lactobacillus population. This is not something you can control, but it helps explain why some women struggle with recurrence while others never have BV at all.

Why Does BV Keep Coming Back After Treatment?

Standard treatment for BV is a course of antibiotics, usually metronidazole or clindamycin, either as pills or vaginal gel. These antibiotics are effective at killing the overgrown bacteria. Symptoms typically clear within a few days. But here is the problem: the antibiotics do not reliably restore the lactobacillus population. Once the antibiotics stop, the vagina is left in a vulnerable state.

Think of it like clearing a field of weeds but not planting new grass. The weeds grow back faster than the grass can establish. In the same way, the harmful bacteria can recolonize faster than lactobacillus can repopulate. One study found that within three months of treatment, about 30 percent of women had a recurrence. By 12 months, that number climbed to 50 percent or higher.

Another reason BV returns is biofilm. Some bacteria, especially Gardnerella, can form a sticky, protective layer on the vaginal walls. This biofilm shields them from antibiotics and allows them to survive treatment. Once the antibiotic is gone, the biofilm acts as a reservoir, and the bacteria spread out again. This is a major focus of current research as of 2026.

Sex without a condom can also reintroduce bacteria from a partner. While BV is not an STI, the bacteria involved can be passed between partners. Using condoms consistently has been shown to reduce recurrence rates in some studies.

What Does The Research Say About Preventing Recurrence?

Several strategies have been studied, and the evidence is mixed. The most promising approach involves using a vaginal probiotic that contains specific lactobacillus strains. Not all probiotics are the same. The strains that matter for vaginal health are Lactobacillus crispatus, Lactobacillus jensenii, and Lactobacillus rhamnosus. These are the ones that produce the most acid and hydrogen peroxide.

A 2020 randomized trial found that women who used a vaginal probiotic containing L. crispatus after antibiotic treatment had a significantly lower recurrence rate at 12 weeks compared to those who used a placebo. However, oral probiotics have shown less consistent results. The bacteria in oral supplements have to survive stomach acid and then travel to the vagina, which is not guaranteed.

Boric acid vaginal suppositories are another option that has gained attention. Some studies suggest that boric acid can disrupt biofilm and help clear stubborn BV. It is not a first-line treatment, and it should never be taken by mouth. But for women with recurrent BV, some clinicians recommend a course of boric acid after antibiotics to help prevent return.

Lifestyle changes have weaker evidence but are still worth considering. Avoiding douching is essential. Using unscented, gentle soaps and skipping bubble baths may help. Wearing cotton underwear and avoiding tight synthetic clothing can reduce moisture and irritation. Some women report that reducing sugar intake helps, though the evidence for this is anecdotal at best.

How Is BV Different From Yeast Infections Or Trichomoniasis?

Many women confuse BV with other vaginal infections because the symptoms can overlap. But the causes and treatments are very different. The table below breaks down the key differences.

If you are not sure what you have, do not guess. Over-the-counter yeast infection treatments will not help BV and can make things worse by disrupting the microbiome further. A simple test at your doctor’s office can tell you exactly what you are dealing with.

What Should You Avoid When Trying To Manage BV?

There is a lot of bad advice online about BV. Some of it is harmless but useless. Some of it can actually make things worse. Here is what to skip.

• Douching. This is the single worst thing you can do. It washes out protective bacteria and increases the risk of BV and other infections. The vagina is self-cleaning. It does not need help.
• Yogurt or garlic inserted vaginally. These are popular home remedies with no good evidence behind them. Yogurt may introduce bacteria, but not necessarily the right strains. Garlic can burn and irritate sensitive tissue.
• Apple cider vinegar baths or rinses. Vinegar is acidic, but the vagina has its own pH regulation system. Pouring vinegar on it can cause irritation and disrupt the balance further.
• Essential oils like tea tree oil. These are often too concentrated and can cause chemical burns or allergic reactions on vaginal tissue.
• Overusing antibiotics. Taking antibiotics for every recurrence is not a long-term solution. It can lead to resistance and further damage the microbiome. Work with a doctor on a plan that includes prevention strategies.

One more thing to avoid: self-diagnosing and self-treating for months on end. If you have had BV multiple times and it keeps coming back, see a gynecologist. There may be an underlying issue like a retained tampon, an IUD that is contributing to the imbalance, or a condition like diabetes that makes you more prone to infections.

Common Misconceptions About BV

One widespread myth is that BV is caused by being unclean. This is simply not true. In fact, women who wash too aggressively or use scented products are more likely to get BV. The vagina is a self-regulating ecosystem. The less you interfere with it, the better it works.

Another misconception is that BV is harmless and does not need treatment. While BV often clears on its own, leaving it untreated in some cases can increase the risk of pelvic inflammatory disease, which can affect fertility. In pregnant women, BV has been linked to preterm birth. If you have symptoms, it is worth treating.

Some people also believe that BV means you have an STI or that your partner gave it to you. As discussed, BV is not an STI. However, having a new partner or multiple partners does increase the risk. This is likely because introducing new bacteria can temporarily disrupt the existing balance.