Bacterial Vaginosis (BV) Fact Sheet

Updated August 2025

Definition

Bacterial Vaginosis (BV) is a type of vaginal infection that occurs when there is an imbalance in the normal bacteria found in the vagina.

Signs and Symptoms

People with BV may notice a thin off-white or grey vaginal discharge with an unpleasant or fishy odour, especially after sex. Less commonly there may also be itching or burning in or near the vagina. However, most people have no symptoms.

Causes

A number of different bacteria live in a healthy vagina. BV can develop when the number of normal vaginal bacteria decrease and are replaced with other bacteria.

Diagnosis

If someone has symptoms, a doctor or nurse can perform an exam to look for signs of BV and collect a swab of the vaginal discharge to diagnose the infection.

Complications (that may arise)

BV itself is not harmful, but it has been associated with some health risks.

Research shows:

  • A link between BV and Pelvic Inflammatory Disease (PID). This is when the infection can spread to the uterus and fallopian tubes. The risk of PID is higher after an IUD insertion, abortion or other gynaecological surgeries.
  • A link between BV and an increased risk of becoming HIV positive if you are exposed to HIV.
  • A link between BV and increased risk of getting other sexually transmitted infections (STIs) such as chlamydia, gonorrhea and herpes if you are exposed to these infections.
  • In pregnancy, a link between BV and premature birth or early breaking of the amniotic sac (your “water breaking”).

Risk Factors

BV is more common in people who have had sexual intercourse. Not much is known about how people get BV or how to prevent it. However, there are certain factors that can put someone at increased risk of BV including having a new sexual partner, having multiple sexual partners, not using condoms, and douching. Someone can have BV even if they have never been sexually active.

Treatment

If you have BV and symptoms, your healthcare provider will probably treat you with antibiotics. The most common medication used is called metronidazole (Flagyl). Some people may feel nauseated or have diarrhea when taking this medication, while others may notice a dry metallic or bitter taste in their mouth. You should not drink alcohol during treatment and for 24 hours afterwards. Alcohol and metronidazole taken together can cause severe nausea and vomiting.

If you have no symptoms of BV, treatment is usually not recommended except in specific situations.

If you are pregnant or breastfeeding, talk to your health care provider before taking any medication.

BV can come back after treatment. It can also sometimes clear up without treatment.

Prevention

Here are a few important points to remember:

  • Don’t use feminine hygiene sprays or wash with soap inside the vagina.
  • Don’t douche. Douching increases your chance of getting BV because it changes the normal acid balance in the vagina.
  • Use condoms correctly every time you have sex to lower your chance of getting BV or a STI.

Self-care

Remember that your vagina cleans itself. It is only necessary to clean the outer genitals with warm water.

Information for Sexual Partners (for STIs)

New studies show that treating male partners of females with recurrent BV may be helpful.

Female sex partners should be tested for BV if they have symptoms.

For More Information

Call the Sexual Health Infoline Ontario at 416-392-2437 (1-800-668-2437) or visit toronto.ca/health

Safer sex: To reduce your risk of getting a sexually transmitted infection (STI), use a condom every time you have vaginal, anal or oral sex.