Bacterial Vaginosis

Bacterial Vaginosis

Condition Basics

What is bacterial vaginosis?

Bacterial vaginosis is an infection of the vagina that may cause a fishy-smelling discharge. It's usually a mild problem that may go away on its own in a few days. But it can lead to more serious problems. So it's a good idea to see your doctor and get treatment.

What causes it?

In women who have bacterial vaginosis, there aren't enough "good" bacteria and are too many "bad" bacteria in the vagina. Experts aren't sure what causes the bacteria to get out of balance. But certain things make it more likely to happen, such as douching or having a new sex partner.

What are the symptoms?

The most common symptom of bacterial vaginosis is a smelly vaginal discharge. It may look greyish white or yellow. It may have a bothersome "fishy" smell, which may be worse after sex. Many women with the infection don't notice any symptoms.

How is it diagnosed?

Doctors diagnose bacterial vaginosis by asking about the symptoms, doing a pelvic examination, and taking a sample of the vaginal discharge. The sample can be tested to find out if you have bacterial vaginosis.

How is bacterial vaginosis treated?

Treatment for bacterial vaginosis includes antibiotic medicine. Depending on the medicine prescribed, these may be taken either by mouth or in the vagina. Antibiotics kill the "bad" bacteria that cause symptoms. But symptoms often come back after antibiotic treatment.


Normally, there are a lot of "good" bacteria and some "bad" bacteria in the vagina. The good types help control the growth of the bad types. In women who have bacterial vaginosis, the balance is upset. There aren't enough good bacteria, and there are too many bad bacteria.

Experts aren't sure what causes the bacteria in the vagina to get out of balance. But certain things make it more likely to happen. Your risk of getting bacterial vaginosis is higher if you:

  • Have more than one sex partner or have a new sex partner.
  • Douche.

Bacterial vaginosis is more common in women who are sexually active. But women who aren't having sex can also get it.


Here are some tips to help prevent bacterial vaginosis.

  • Limit the number of sex partners you have.
  • Avoid douching.
  • Use condoms consistently.
  • Practice good hygiene.

    Bacterial vaginosis may be passed between women during sexual contact. If you have a female sex partner, you may benefit from using protection and carefully washing shared sex toys.

  • Practice safer sex.

    It is always important to practice safer sex to prevent sexually transmitted infections, whether or not you have bacterial vaginosis. Preventing an STI is easier than treating an infection after it occurs.

Bacterial vaginosis is generally not considered a sexually transmitted infection (STI). But if you are exposed to an STI while you have bacterial vaginosis, you are more likely to get that infection.

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Many women who have bacterial vaginosis don't notice any symptoms. It doesn't typically cause itching. But it does cause:

  • Lots of vaginal discharge that's not like normal discharge. It may look greyish white or yellow. This is the most common symptom.
  • A bothersome "fishy" odour. The smell is usually worse after sex (intercourse).

The symptoms are similar to some sexually transmitted infections (such as trichomoniasis, chlamydia, and gonorrhea) and to a vaginal yeast infection.

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What Happens

Bacterial vaginosis often clears up on its own. But in some women it doesn't go away on its own. And for many women it comes back after it has cleared up. Antibiotic treatment works for some women but not others.

Bacterial vaginosis usually doesn't cause other health problems. But in some cases it can lead to serious problems.

  • If you have it when you are pregnant, it increases the risk of miscarriage, early (preterm) delivery, and uterine infection after pregnancy.
  • If you have it when you have a pelvic procedure such as a caesarean section, an abortion, or a hysterectomy, you are more likely to get a pelvic infection.
  • If you have it and you are exposed to a sexually transmitted infection (including HIV), you are more likely to catch the infection.

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When to Call

Bacterial vaginosis can be hard to distinguish from other types of vaginal infection. Consider the following if you have any signs of vaginal infection.

Call your doctor now if you:

  • Have pain in your lower belly and a fever higher than 38.3°C (101°F) along with a vaginal discharge.
  • Are pregnant and have symptoms of a vaginal infection.

Call your doctor for an appointment if you:

  • Have vaginal discharge with an unusual or foul odour.
  • Have vaginal itching.
  • Have pain during sex or during urination.
  • Develop any other discomfort or discharge that may mean you have a vaginal infection.

Watchful waiting

It's a good idea to contact or see your doctor about unusual vaginal symptoms.

If your symptoms are due to a sexually transmitted infection (STI) and not bacterial vaginosis, you may infect a sex partner if you delay treatment. You may also develop more serious complications of STIs such as pelvic inflammatory disease (PID).

  • To prevent the spread of a possible infection, avoid sex. Wait until after you have seen your doctor.
  • Avoid douching.

Check your symptoms

Exams and Tests

Doctors diagnose bacterial vaginosis by asking about symptoms, doing a pelvic examination, and taking a sample of the vaginal discharge. The sample can be tested for bacterial vaginosis.

These lab tests may include:

Wet mount.

A sample of discharge is checked for bacteria, white blood cells, and unusual cells called clue cells. These clue cells are one sign of bacterial vaginosis.

Whiff test.

A special solution is added to a sample of discharge to see if it gives off a strong fishy odour. This odour usually means you have bacterial vaginosis.

Vaginal pH.

The pH of a sample of vaginal discharge is measured. Bacterial vaginosis often causes a pH that is higher than normal.

Oligonucleotide probes.

This test looks for the genetic material (DNA) of bacterial vaginosis bacteria.

The presence of clue cells, an increased vaginal pH, and a positive whiff test are enough evidence to treat for bacterial vaginosis.

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Treatment Overview

For some women, bacterial vaginosis goes away without treatment. But doctors usually prescribe an antibiotic medicine. Antibiotics kill the "bad" bacteria that cause symptoms. The medicine may be pills you swallow. Or it might be a cream or capsules that you put in your vagina. In many cases, symptoms come back after antibiotic treatment. This can be frustrating.

Bacterial vaginosis makes the reproductive tract vulnerable to infection or inflammation. So your doctor will test and treat you with antibiotics if you are:

  • Having symptoms that won't go away.
  • Pregnant and having symptoms.
  • Planning to have a hysterectomy or surgical abortion. Taking antibiotics in advance may lower your risk of getting a serious infection afterward.

Talk to your doctor about whether testing is right for you.


  • Take your antibiotics as directed. Do not stop taking them just because you feel better. You need to take the full course of antibiotics.
  • Do not eat or drink anything that contains alcohol if you are taking metronidazole.
  • Keep using your medicine if you start your period. Use pads instead of tampons while using a vaginal cream or suppository. Tampons can absorb the medicine.
  • Wear loose cotton clothing. Do not wear nylon and other materials that hold body heat and moisture close to the skin.
  • Do not scratch. Relieve itching with a cold pack or a cool bath.
  • Do not wash your vaginal area more than once a day. Use plain water or a mild, unscented soap. Do not douche.

Can yogurt help?

Some women have tried treating bacterial vaginosis with the probiotic Lactobacillus. This is found in foods like yogurt and in dietary supplements. But more research is needed to find out if it works to treat or prevent bacterial vaginosis. It's also not clear which type of Lactobacillus would work best.


The antibiotics metronidazole (such as Flagyl and MetroGel) and clindamycin (such as Dalacin) are used to treat bacterial vaginosis.

When thinking about treatment, ask your doctor if you should:

  • Use medicine that you take by mouth or insert into your vagina. Let your doctor know which you prefer. If you are pregnant, your doctor likely will prescribe oral medicine.
  • Avoid having sex during the time that you are being treated.
  • Continue treatment during your menstrual period.
  • Avoid drinking alcohol during treatment with metronidazole. This medicine can cause nausea and vomiting if you drink alcohol.
  • Use condoms during your treatment. The oil in clindamycin cream and ovules can weaken latex. This means condoms and diaphragms may break and not protect you against STIs or pregnancy.

Learn more


Current as of: November 22, 2021

Author: Healthwise Staff
Medical Review:
Sarah Marshall MD - Family Medicine
Kathleen Romito MD - Family Medicine
Martin J. Gabica MD - Family Medicine
Devika Singh MD, MPH - Infectious Disease