Bacterial vaginosis

At a glance

  • In bacterial vaginosis, the natural balance of germs in the vagina (the vaginal flora) is disrupted.
  • As a result, certain bacteria can grow a lot more than they normally do.
  • The infection often goes unnoticed, but it may lead to a vaginal discharge with a strong fishy smell.
  • If bacterial vaginosis causes symptoms, it is usually treated with antibiotics – even in pregnant women.


Photo of a couple taking a stroll along the beach

In bacterial vaginosis, certain in the vagina grow a lot more than they normally do.

This is usually not dangerous and it often goes unnoticed. But it may cause a strong-smelling vaginal discharge and be very unpleasant. It also increases the risk of a vaginal . Vaginal infections can be treated effectively with .


At least half of the women who have bacterial vaginosis don’t have any symptoms. If they do have symptoms, the most common one is a watery, grayish-white vaginal discharge that has a strong fishy smell. Many women find this smell unpleasant. It is often stronger after sex or during menstruation.

Symptoms like itching, burning and vaginal dryness are more likely to be signs of vaginitis (an of the vagina). In that case, the area around the opening of the vagina is usually red and the lining of the vagina is swollen. Vaginitis can also lead to problems when urinating (peeing) or during sex.


The vagina mostly contains lactic acid . Together with other “good” germs, they make up the vaginal flora and help to keep the vagina slightly acidic. The right acidity (pH level) protects the vagina from harmful germs. Bacterial vaginosis is caused by an imbalance in this acidic environment: The number of lactic acid drops, and other in the vagina can then multiply (grow) a lot. Bacterial vaginosis is usually caused by a type of called Gardnerella vaginalis.

Risk factors

The risk of bacterial vaginosis is higher in women who are very sexually active and, for example, have a new partner or switch partners frequently.

Hormonal changes or washing your genital area too much can cause an imbalance in the vaginal flora and make vaginosis more likely.

Prevalence and outlook

Bacterial vaginosis is one of the most common types of vaginal . It is estimated that about 5 out of 100 women have it. The clears up on its own in about one third of women. Treatment is usually needed if it causes symptoms.


If there’s an imbalance in the vaginal flora, it's easier for other germs to grow there. For that reason, bacterial vaginosis can lead to a vaginal , and that can lead to infections in the womb (uterus) and fallopian tubes. The risk of getting sexually transmitted diseases increases too.

Vaginal infections can also slightly increase the risk of complications in pregnancy, such as early contractions, miscarriage, or premature birth.


It is not always possible to tell the difference between bacterial vaginosis and other types of vaginal infections based only on the symptoms. To find out if it’s vaginosis, a gynecologist examines the vagina and takes a sample of the discharge. This sample (“smear”) can be used to measure the pH level and find out what types of it contains. Samples from women with bacterial vaginosis usually have too many gardnerella in them.


If bacterial vaginosis causes symptoms, it is usually treated with antibiotics to kill the . The can be taken in the form of tablets that are swallowed, or suppositories or creams that are applied directly in the vagina. It is not necessary to treat your partner, though – the treatment doesn't prevent future infections.

Another treatment option is suppositories or capsules containing living lactic acid . These treatments are designed to protect the vaginal flora and restore the correct balance. But there isn’t enough scientific proof that they work.

Some women also try things like soaking tampons in tea tree oil or natural yogurt and putting them inside their vagina to create a more acidic environment there. But there is a lack of research on the safety and efficacy of these kinds of home remedies.

Amaya-Guio J, Viveros-Carreno DA, Sierra-Barrios EM et al. Antibiotic treatment for the sexual partners of women with bacterial vaginosis. Cochrane Database Syst Rev 2016; (10): CD011701.

Centers for Disease Control and Prevention (CDC). Sexually Transmitted Infections Treatment Guidelines, 2021. (Morbidity and Mortality Weekly Reports: Recommendations and Reports). MMWR 2021; 70(4): 1-187.

Deutsche Gesellschaft für Gynäkologie und Geburtshilfe (DGGG). Bakterielle Vaginose (BV) in Gynäkologie und Geburtshilfe (S2k-Leitlinie, in Überarbeitung). AWMF-Registernr.: 015-028. 2021.

Hainer BL, Gibson MV. Vaginitis. Am Fam Physician 2011; 83(7): 807-815.

Li C, Wang T, Li Y et al. Probiotics for the treatment of women with bacterial vaginosis: A systematic review and meta-analysis of randomized clinical trials. Eur J Pharmacol 2019; 864: 172660.

Oduyebo OO, Anorlu RI, Ogunsola FT. The effects of antimicrobial therapy on bacterial vaginosis in non-pregnant women. Cochrane Database Syst Rev 2009; (3): CD006055.

Spence D, Melville C. Vaginal discharge. BMJ 2007; 335(7630): 1147-1151.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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Updated on April 4, 2022

Next planned update: 2025


Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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