Mayo Clinic Health Library

Bacterial vaginosis

Updated: 04-20-2013

Definition

Bacterial vaginosis is a type of vaginal inflammation that results from the overgrowth of one of several types of bacteria normally present in the vagina, upsetting the natural balance of vaginal bacteria.

Women in their reproductive years are most commonly affected by bacterial vaginosis, but any woman can experience the condition. Doctors don't know exactly why bacterial vaginosis develops, but certain activities, such as unprotected sexual intercourse or frequent douching, put you at higher risk of the condition.

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Symptoms

Bacterial vaginosis signs and symptoms may include:

  • Vaginal discharge that's thin and grayish white
  • Foul-smelling "fishy" vaginal odor, especially after sexual intercourse
  • Vaginal itching
  • Burning during urination

However, many women with bacterial vaginosis have no signs or symptoms at all.

When to see a doctor
You probably need to see your doctor if you have new vaginal symptoms and:

  • You've never had a vaginal infection. Seeing your doctor will establish the cause and help you learn to identify signs and symptoms.
  • You've had vaginal infections before, but these symptoms seem different.
  • You've had multiple sex partners or a recent new partner. You could have a sexually transmitted infection. Signs and symptoms of some sexually transmitted infections are similar to those of bacterial vaginosis.
  • You've tried self-treatment for a yeast infection with an over-the-counter anti-yeast medication and your symptoms persist, you have a fever, or you have a particularly unpleasant vaginal odor.
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Causes

Bacterial vaginosis results from an overgrowth of one of several organisms normally present in your vagina. Usually, "good" bacteria (lactobacilli) outnumber "bad" bacteria (anaerobes) in your vagina. But if anaerobic bacteria become too numerous, they upset the natural balance of microorganisms in your vagina, resulting in bacterial vaginosis.

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Risk factors

Risk factors for bacterial vaginosis include:

  • Multiple sex partners or a new sex partner. The link between sexual activity and bacterial vaginosis isn't entirely clear, but bacterial vaginosis occurs more often in women who have multiple sex partners or a new sex partner. Bacterial vaginosis also seems to occur more frequently in women who have sex with women.
  • Douching. The practice of rinsing out your vagina with water or a cleansing agent (douching) upsets the natural balance of your vaginal environment. This can lead to an overgrowth of anaerobic bacteria, which in turn can result in bacterial vaginosis. Since the vagina is self-cleaning, douching isn't necessary.
  • Natural lack of lactobacilli bacteria. If your natural vaginal environment doesn't produce enough of the good lactobacilli bacteria, you're more likely to develop bacterial vaginosis.
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Complications

Generally, bacterial vaginosis doesn't cause complications. But under certain circumstances, having bacterial vaginosis may lead to:

  • Preterm birth. In pregnant women, bacterial vaginosis is linked to premature deliveries and low birth weight babies.
  • Sexually transmitted infections. Having bacterial vaginosis makes women more susceptible to sexually transmitted infections, such as HIV, herpes simplex virus, chlamydia or gonorrhea. If you have HIV, bacterial vaginosis increases the odds that you'll pass the virus on to your partner.
  • Infection risk after gynecologic surgery. Having bacterial vaginosis may be associated with a greater chance of developing a post-surgical infection after procedures such as hysterectomy or dilation and curettage (D&C).
  • Pelvic inflammatory disease (PID). Bacterial vaginosis can sometimes cause PID, an infection of the uterus and the fallopian tubes that can increase the risk of infertility.
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Preparing for your appointment

So that your primary care doctor or gynecologist can observe and evaluate any vaginal discharge you have, don't schedule your appointment during your period. Avoid using tampons and vaginal deodorant sprays, and don't douche or have sex for 24 hours before your appointment.

What you can do
Because appointments can be brief, and it may be difficult to remember everything you want to discuss, it's a good idea to prepare in advance of your appointment.

  • Make a list of any symptoms you're experiencing. Include all of your symptoms, even if you don't think they're related.
  • Make a list of any medications, vitamins, herbs or other supplements you take. Include how often you take them and the doses.
  • Take a notepad or electronic device with you. Use it to make notes of important information during your visit.
  • Prepare a list of questions to ask your doctor. List your most important questions first, in case time runs out.

For bacterial vaginosis, some basic questions to ask your doctor include:

  • Can I do anything to prevent bacterial vaginosis?
  • What signs and symptoms should I look for?
  • Do I need to take medicine?
  • Does my partner also need to be tested or treated?
  • Are there any special instructions for taking the medicine?
  • Are there any over-the-counter products that will treat my condition?
  • What can I do if my symptoms return after treatment?

Don't hesitate to ask questions during your appointment if you don't understand something.

Questions your doctor may ask
Be prepared to answer questions your doctor may have, such as:

  • What symptoms are you experiencing?
  • How long have you had your symptoms?
  • Do you notice a strong vaginal odor?
  • Have you ever been treated for a vaginal infection?
  • Have you tried any over-the-counter products to treat your condition?
  • Have you recently taken antibiotics for any reason?
  • Are you sexually active?
  • Are you pregnant?
  • Do you use scented soap or bubble bath?
  • Do you douche or use feminine hygiene spray?
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Tests and diagnosis

To diagnose bacterial vaginosis, your doctor may:

  • Ask questions about your medical history. Specifically, your doctor may ask about any previous vaginal infections or sexually transmitted infections.
  • Perform a pelvic exam. During a pelvic exam, your doctor visually examines your external genitalia for signs of vaginal infection and inserts two fingers into your vagina while pressing on your abdomen with the other hand to check your pelvic organs for unusual characteristics that may indicate disease.
  • Take a sample of vaginal secretions. This may be done to check for an overgrowth of anaerobic bacteria in your vaginal flora. Your doctor may examine the vaginal secretions under a microscope, looking for "clue cells," vaginal cells covered with bacteria that are a sign of bacterial vaginosis. Your doctor may also check the acidity of your vaginal environment by placing a pH test strip in your vagina. A vaginal pH of 4.5 or higher is another sign of bacterial vaginosis.
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Treatments and drugs

To treat bacterial vaginosis, your doctor may prescribe one of the following medications:

  • Metronidazole (Flagyl, Metrogel-Vaginal, others). This medicine may be taken orally — as a pill that you swallow. Metronidazole is also available for use topically, as a gel that you insert into your vagina. To avoid the potential for stomach upset, abdominal pain or nausea while using this medication, avoid alcohol during treatment and for at least one day after completing treatment — check the instructions on the product.
  • Clindamycin (Cleocin, Clindesse, others). This medicine is available as a cream that you insert into your vagina. One effect of using clindamycin cream is that it may weaken latex condoms during treatment and for at least three days after you stop using the cream.
  • Tinidazole (Tindamax). This medication is taken orally. Tinidazole has the same potential for stomach upset and nausea as oral metronidazole does, so avoid alcohol during treatment and for at least one day after completing treatment.

Generally, it's not necessary to treat a woman's male sexual partner, but bacterial vaginosis can spread between female sexual partners. Female partners should seek testing and, if indicated, treatment of bacterial vaginosis. It's especially important for pregnant women with symptoms to be treated, as this may decrease the risk of premature delivery or low birth weight.

Take your medicine or use the cream or gel for as long as your doctor prescribes it — even if your symptoms go away. Stopping treatment early may increase the likelihood of recurrence.

Recurrence
Despite effective treatments for bacterial vaginosis, recurrence of symptoms within three to 12 months is common. Researchers are exploring treatment regimens for recurrent bacterial vaginosis. If your symptoms recur soon after treatment, talk with your doctor about treatment options, one of which is extended-use metronidazole therapy.

A self-help approach is lactobacillus colonization therapy — which attempts to boost the number of good bacteria in your vagina and re-establish a balanced vaginal environment — possibly accomplished by eating certain types of yogurt or other foods containing lactobacilli. However, research to determine the benefits and risks of probiotic therapy is lacking.

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Prevention

To help prevent bacterial vaginosis:

  • Minimize vaginal irritation. Stay out of hot tubs and whirlpool spas. Rinse soap from your outer genital area after a shower, and dry the area well to prevent irritation. Use mild, nondeodorant soaps and unscented tampons or pads.
  • Don't douche. Your vagina doesn't require cleansing other than normal bathing. Repetitive douching disrupts the normal organisms that reside in the vagina and can actually increase your risk of vaginal infection. Douching won't clear up a vaginal infection.
  • Avoid a sexually transmitted infection. Use a male latex condom, limit your number of sex partners or abstain from intercourse to minimize your risk of a sexually transmitted infection.
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