How Do You Get Bacterial Vaginosis (BV)?

What Is Bacterial Vaginosis (BV)?

A fishy smelling vaginal discharge is an early sign of BV.
A fishy smelling vaginal discharge is an early sign of BV.

Bacterial vaginosis (BV) is a vaginal infection and a common cause of abnormal vaginal discharge in women. Bacteria that may cause BV include Gardnerella vaginalis with other bacteria, such as Lactobacillus, Prevotella, and anaerobes, including Mobiluncus, Bacteroides, Peptostreptococcus, Fusobacterium, Veillonella, and Eubacterium. Mycoplasma hominis, Ureaplasma urealyticum, Streptococcus viridans, and Atopobium vaginae.

What Are the Signs and Symptoms of Bacterial Vaginosis?

Between 50%-75% of women with bacterial vaginosis may have no symptoms or signs. When symptoms and signs of bacterial vaginosis occur, they may include the following:

  • Vaginal odor, may be fishy smelling (the most common and often earliest symptom)
  • Increased vaginal discharge that is off-white in color and thin consistency
  • Itching (in some patients)
  • Vulvar irritation (less common)
  • Pain, discomfort, or burning on urination (rare)
  • Painful sexual intercourse (rare)

On physical examination, a doctor may notice

  • gray thin vaginal discharge that sticks to the vaginal walls;
  • increased light reflex of the vaginal walls;
  • little or no evidence of inflammation;
  • inflammation of the cervix (cervicitis) in some cases; and
  • usually the labia, vaginal entrance, cervix, and cervical discharge appear normal.

What Causes Bacterial Vaginosis?

The cause of bacterial vaginosis is a change in the number and types of bacteria in the vagina, however, the reason these changes occur is unknown. In women with BV, the number of Lactobacilli, a type of bacteria normally found in the vagina, is reduced.

Risk factors for developing bacterial vaginosis include the following:

How Do Doctors Diagnose Bacterial Vaginosis?

To diagnose bacterial vaginosis, a doctor will first get a history and perform a pelvic examination, however, microscopic examination of the vaginal discharge is needed to determine if the vaginal discharge is caused by BV or another vaginal infection.

It may be necessary to test for other infections (for example, N. gonorrhoeae, C. trachomatis, or herpes simplex virus [HSV]-1).

What Is the Treatment for Bacterial Vaginosis?

The standard treatment for bacterial vaginosis involves treatment with antibiotics and antifungals, usually metronidazole (Flagyl) or clindamycin (Cleocin).

Both medications need must be taken for multiple days and can be taken in pill form by mouth, or with a gel or cream inserted inside the vagina.

The single-dose oral medication secnidazole (Flagentyl, Sindose, Secnil, Solosec) is another treatment option, but it is usually more expensive and is no more effective than metronidazole or clindamycin.

About 30% of women have a recurrence of symptoms and signs within 3 months, and more than 50% experience a recurrence within 12 months. A prolonged 7-day course of metronidazole and clindamycin treats relapses of BV. The Centers for Disease Control and Prevention (CDC) recommends re-treatment be in a different form than the original treatment (for example, use oral treatment if the patient previously used a vaginal treatment, and vice versa).

Patients should avoid douche, bubble bath, and any other over-the-counter vaginal hygiene products. Cleanse with hypoallergenic bar soaps or no soap, and avoid liquid soaps and body washes.

What Are Complications of Bacterial Vaginosis?

Bacterial vaginosis in itself may not cause complications, but it can lead to a higher risk of certain conditions:

How Do You Prevent Bacterial Vaginosis?

Bacterial vaginosis may be preventable in some cases with lifestyle modifications:

  • Do not douche.
  • Always use condoms for sex.
  • Limit your number of sexual partners.
  • Don't smoke.
  • Birth control pills may be helpful, but male partners of women with recurring BV should use condoms.
  • If you are undergoing treatment for BV, finish the entire prescribed course of medication even if symptoms and signs improve after a few doses.
Girerd, Philippe. "Bacterial Vaginosis." Oct. 25, 2018. <>.

Sobel, Jack D. "Patient education: Bacterial vaginosis (Beyond the Basics)." April 2020. <>.