What Is Bacterial Vaginosis?

Bacterial vaginosis itself does not have distinct subtypes, but it is important to tell it apart from other vaginal infections that can look similar. Yeast infections are caused by a fungus called Candida. They typically produce a thick, white discharge that looks like cottage cheese, with intense itching but no odor. Trichomoniasis is a sexually transmitted infection caused by a parasite. It often causes a greenish, frothy discharge with a strong odor. BV can also be classified by how often it occurs:

• Acute BV refers to new or occasional episodes that respond well to a standard course of antibiotics.
• Recurrent BV means you get it four or more times in a year. About half of people treated for BV will experience recurrence, and it can be more challenging to manage.

About half of all people with bacterial vaginosis have no symptoms at all. When symptoms do appear, they can range from mild to more noticeable. The most common symptoms include:

• A thin, watery discharge that may be white, gray, or greenish
• A strong fishy odor, especially after unprotected sex
• Burning or discomfort when you urinate
• Vaginal itching, irritation, or general discomfort
• Pain during sex in some cases
• Mild lower abdominal pain (less common)

The fishy odor is a hallmark of BV. It often becomes stronger after sex or during your period because semen and blood can temporarily raise the pH of your vagina. The discharge is typically thinner and more watery than what is normal for you. Because BV symptoms can overlap with yeast infections and other conditions, it is a good idea to see a healthcare provider for simple tests that can confirm the cause and get you the right treatment.

Bacterial vaginosis happens when the normal balance of bacteria in your vagina is thrown off. A healthy vagina is home to many different microorganisms, but the most important ones are called Lactobacillus. These friendly bacteria produce lactic acid and hydrogen peroxide, keeping the vagina slightly acidic with a pH between 3.8 and 4.5. This acidity keeps harmful bacteria from growing out of control. In BV, the protective Lactobacillus bacteria decrease, and other bacteria — especially Gardnerella, Prevotella, and Mobiluncus — multiply rapidly. These harmful bacteria can reach levels 100 to 1,000 times higher than normal, overwhelming the vagina’s natural defenses and causing the discharge and odor that characterize BV. Doctors do not know exactly why this imbalance happens, but certain things can increase your risk:

• Smoking
• Douching (washing inside the vagina)
• Having a new sex partner or multiple partners
• Not using condoms
• Using an intrauterine device (IUD) for birth control
• Naturally low levels of Lactobacillus
• Taking antibiotics (which can kill good bacteria along with bad)
• Hormonal changes from pregnancy or menopause

BV is not a sexually transmitted infection, and it can happen in people who have never had sex. However, sexual activity can temporarily change the pH of the vagina and introduce new bacteria. People with vaginas who have female partners are at higher risk. BV can be passed between female partners through vaginal fluids and shared sex toys. You cannot get BV from swimming pools, toilet seats, bedding, or towels.

Diagnosing BV is usually straightforward. A healthcare provider can often tell if you have it with a brief examination and a few simple tests. Because BV can look like other infections, getting an accurate diagnosis is important so you receive the right treatment. The process typically includes: Your doctor will ask about your symptoms, medical history, and any recent sexual activity. They will perform a pelvic exam to check the appearance of your vagina and cervix and note the characteristics of any discharge. Several specific tests can confirm BV:

• Vaginal pH test: A sample of fluid is tested for acidity. A pH above 4.5 is a sign of BV.
• Wet mount microscopy: A sample of discharge is looked at under a microscope. The presence of clue cells — vaginal cells covered with bacteria — confirms BV.
• Whiff test (amine test): A drop of potassium hydroxide solution is added to a sample. If a strong fishy odor is released, the test is positive.
• PCR testing: This looks for DNA from BV-causing bacteria. It is very sensitive but not used as often because it costs more.

Home test kits are available at drugstores, but they are not always accurate. It is best to see a healthcare provider for a reliable diagnosis and to rule out other infections that may need different treatment.

While BV cannot always be prevented, there are several things you can do to lower your risk:

• Avoid douching. The vagina cleans itself and does not need to be washed internally. Douching is one of the strongest risk factors for BV.
• Use condoms or dental dams during sex. Barrier methods help protect the natural pH of your vagina.
• Limit your number of sex partners. Fewer partners means less exposure to different bacteria that can disrupt your vaginal balance.
• Wear cotton or cotton-lined underwear. Breathable fabrics reduce moisture that bacteria thrive in. Avoid tight, synthetic clothing for long periods.
• Clean your genital area gently with warm water and mild, unscented soap. Skip scented washes, bubble baths, vaginal deodorants, and sprays.
• Wipe from front to back after using the bathroom. This prevents bacteria from your anal area from reaching your vagina.
• Avoid scented tampons, pads, and liners. They can irritate the vagina and disturb its natural balance.
• Clean sex toys after each use with warm water and mild soap.
• Consider probiotics. Yogurt, kefir, and Lactobacillus supplements may help maintain healthy vaginal bacteria. The evidence is still growing, but they are generally safe to try.
• If you smoke, quitting may lower your risk. Smoking is linked to higher rates of BV.

For people who get BV often, a healthcare provider may recommend suppressive therapy — using a metronidazole vaginal gel two to three times a week for several months to keep BV from coming back.

The outlook for BV is very good with treatment. Most people notice their symptoms start to improve within two to three days of starting antibiotics, and the infection usually clears completely by the end of the medication course. However, recurrence is a real challenge. About half of all people treated for BV will have another episode within 12 months. It can sometimes come back within just a few weeks. Doctors are not sure why recurrence is so common, but possible reasons include:

• The original infection did not fully clear
• Reinfection from a sexual partner
• A persistent disruption in the vaginal microbiome that makes it hard to restore a healthy balance

Several strategies can help improve your long-term outlook:

• Always finish your entire course of antibiotics, even if you feel better before they are gone
• If you get BV often, talk to your doctor about a longer course of treatment or suppressive therapy
• A 2025 study found that treating male partners with antibiotics significantly reduced recurrence in heterosexual couples

Untreated BV can lead to complications:

• Increased risk of sexually transmitted infections, including HIV, chlamydia, and gonorrhea
• Pelvic inflammatory disease (PID), which can affect fertility
• In pregnancy: higher risk of preterm birth, low birth weight, and miscarriage

This is why treating BV is important even if you do not have symptoms — especially if you are pregnant or planning to become pregnant. With the right treatment and prevention habits, most people recover fully and have no lasting health issues.

BV is treated with prescription antibiotics. Over-the-counter yeast infection creams will not help and can delay getting the right treatment. Commonly prescribed antibiotics:

• Metronidazole: Comes as a pill you swallow or a gel you insert into your vagina. This is the most common treatment and works well.
• Clindamycin: A vaginal cream used for about a week. It is a good option if you cannot take metronidazole.
• Secnidazole (Solosec): A single-dose oral granule. You take it once and you are done.
• Tinidazole (Tindamax): An oral tablet taken for a few days.

Important things to know:

• Finish all the medicine even if your symptoms go away. Stopping early can bring the infection back.
• Avoid sex until you finish treatment and your symptoms are gone.
• Do not drink alcohol while taking metronidazole or tinidazole and for at least 24 to 72 hours after your last dose. It can cause severe nausea, vomiting, and cramping.
• If your partner has a vagina, they may also need treatment. Partners with a penis do not usually need treatment, though recent studies suggest it may help prevent recurrence.

Things you can try alongside your doctor’s advice:

• Probiotics from yogurt, kefir, or supplements may help restore healthy bacteria
• Boric acid vaginal suppositories (available over the counter) can help rebalance pH, but only use them under your doctor’s guidance
• Some studies suggest garlic supplements may help, but more research is needed

Always check with your healthcare provider before using home remedies. Some can cause irritation or make things worse.

What you eat cannot cure BV on its own, but it can support your body’s ability to maintain a healthy vaginal microbiome. Foods that may help:

• Yogurt and kefir with live active cultures are the most studied probiotic foods for vaginal health. Eating them regularly may help prevent BV from coming back.
• Fermented vegetables like sauerkraut, kimchi, and other traditionally fermented foods provide beneficial bacteria. They support your gut health, which in turn supports your immune system.
• Kombucha and other fermented drinks may offer similar benefits.

What to limit:

• Too much sugar and refined carbohydrates (white bread, sugary drinks, sweets) can feed harmful bacteria and yeast. Cutting back on sugar supports a healthy microbiome throughout your body.
• Staying hydrated helps all of your mucous membranes, including your vaginal tissues.

A balanced diet with plenty of fruits, vegetables, whole grains, and lean protein supports your immune system and overall health. This helps your body maintain the right bacterial balance naturally. Remember: diet should support your medical treatment, not replace it. If you think you have BV, see a healthcare provider first for an accurate diagnosis and the right antibiotics.

Bacterial vaginosis is a very common condition that happens when the natural balance of bacteria in the vagina is disrupted. When protective bacteria decrease and harmful ones multiply, it can cause a thin, grayish-white discharge with a fishy odor, especially after sex. However, about half of people with BV have no symptoms at all. BV is not an STI, but sexual activity can increase the risk. Diagnosis is simple and involves a pelvic exam, pH test, and sometimes a microscope check. Treatment with prescription antibiotics works well, and most people feel better within a few days. Recurrence is common, affecting about half of those treated within a year, but preventive habits like avoiding douching, using condoms, and good hygiene can reduce the risk. Untreated BV can lead to other health issues, so proper treatment is important. With the right care, most people recover fully with no lasting problems.