Understanding Bacterial Vaginosis: Causes, Symptoms, Treatment and Prevention

Duly Care
Jun 20
8 min read

Bacterial vaginosis (BV) is the most common vaginal infection among women of reproductive age, yet it remains widely misunderstood. Often mistaken for a yeast infection or sexually transmitted infection (STI), BV results from an imbalance in the vaginal microbiome rather than an external pathogen. If left untreated, it can cause discomfort, unusual discharge, and an increased risk of other infections.

Understanding BV - its causes, symptoms, treatments, and preventive measures - can empower women to take charge of their vaginal health.

Key Takeaways

Bacterial vaginosis is caused by an imbalance of vaginal bacteria, not by an external infection.
Common symptoms include unusual discharge, fishy odour, and irritation, though some women experience no symptoms.
BV is diagnosed through clinical examination and laboratory tests. Self-diagnosis is unreliable due to symptom overlap with other vaginal conditions.
Antibiotics like metronidazole or clindamycin are the primary treatments for BV. Probiotics and lifestyle changes may help prevent recurrence.
Untreated BV can increase susceptibility to STIs and complications in pregnancy. Practising safe hygiene and maintaining vaginal pH balance can reduce risk.

What Is Bacterial Vaginosis?

Bacterial vaginosis (BV) is a vaginal condition that occurs when the natural balance of bacteria in the vagina is disrupted. Normally, the vagina maintains a healthy environment dominated by Lactobacillus bacteria, which help keep the pH level acidic and prevent harmful bacteria from overgrowing. However, when this balance is disturbed, anaerobic bacteria such as Gardnerella vaginalis multiply excessively, leading to BV.

Unlike yeast infections, which result from fungal overgrowth, BV is a bacterial imbalance and is considered the most common vaginal infection among women of reproductive age. It can sometimes be asymptomatic, but symptoms often include an unusual discharge with a fishy odour, irritation, and discomfort.

Causes of Bacterial Vaginosis

Under normal, healthy conditions, Lactobacillus bacteria dominate the vaginal flora, maintaining an acidic environment with a pH typically between 3.8 and 4.5. This acidic environment is crucial as it prevents the overgrowth of harmful bacteria and pathogens. Lactobacillus bacteria help to keep the vagina clean and healthy by producing lactic acid, which creates a protective barrier against infections.

However, BV occurs when the population of these beneficial Lactobacillus bacteria decreases, leading to an environment where harmful bacteria can thrive. When this happens, anaerobic bacteria - those that do not require oxygen to grow, such as Gardnerella vaginalis - can overpopulate the vagina. These bacteria are normally present in small amounts but are kept in check by Lactobacillus and other beneficial microorganisms.

Risk Factors

While the exact cause is not always clear, several factors increase the risk of developing BV:

Douching: Disrupts the vaginal microbiome by washing away protective bacteria and altering pH levels, making the environment more susceptible to harmful bacterial overgrowth.
Unprotected sex: Semen has an alkaline pH that can temporarily disrupt the natural acidity of the vagina, fostering bacterial imbalances.
Multiple or new sexual partners: Although BV is not classified as a sexually transmitted infection, research suggests that exposure to different microbiomes through sexual activity may increase the likelihood of developing BV.
Use of intrauterine devices (IUDs): Certain types of IUDs, particularly those without hormones, may be associated with a slightly increased risk of BV due to local inflammatory responses or changes in vaginal bacterial composition.
Antibiotic use: Broad-spectrum antibiotics can indiscriminately eliminate both harmful and beneficial bacteria, reducing Lactobacillus levels and allowing opportunistic bacteria to thrive.
Menstrual cycle variations: Hormonal fluctuations throughout the menstrual cycle can influence vaginal pH and bacterial composition, potentially contributing to imbalances that lead to BV.

What are the Symptoms of Bacterial Vaginosis?

BV symptoms can vary, and some women may not experience any noticeable signs. However, when symptoms do occur, they often include:

Unusual vaginal discharge: The discharge is typically thin, watery, and greyish-white. In some cases, it may appear slightly foamy or increase in quantity.
Strong, fishy odour: The odour is often most noticeable after sexual intercourse, as semen can interact with the bacterial imbalance and amplify the smell.
Vaginal irritation and itching: Some women may experience mild irritation or discomfort in the vaginal area, though this is less common than with yeast infections.
Burning sensation during urination: In some cases, BV can cause mild inflammation that results in a slight burning sensation while urinating.
No symptoms at all: Many women with BV do not experience any symptoms, which makes regular gynaecological checkups crucial for early detection.

Testing for Bacterial Vaginosis

Diagnosing BV requires medical evaluation, as its symptoms can closely resemble those of yeast infections and sexually transmitted infections (STIs). Proper diagnosis helps ensure effective treatment and reduces the risk of complications. The most common diagnostic methods include:

Clinical examination: A doctor assesses symptoms, including vaginal discharge, odour, and irritation, while also checking for signs of other infections.
pH testing: BV-associated discharge typically has a pH higher than 4.5, indicating an imbalance in the vaginal microbiome.
Whiff test: A sample of vaginal fluid is mixed with potassium hydroxide (KOH). If BV is present, the reaction releases a strong fishy odour due to the presence of amines.
Microscopic analysis: A vaginal fluid sample is examined under a microscope to identify "clue cells," which are vaginal epithelial cells coated with bacteria, a key indicator of BV.
Nugent score test: A laboratory method that evaluates the bacterial composition of vaginal flora to confirm BV, providing a more precise diagnosis.

Since self-diagnosis is unreliable, it is essential to consult a doctor for accurate testing and appropriate treatment.

How Can I Treat Bacterial Vaginosis

Antibiotic Treatments

Metronidazole (Flagyl): Available as oral tablets or a vaginal gel, metronidazole is one of the most commonly prescribed treatments for BV. It works by eliminating the overgrowth of anaerobic bacteria responsible for the condition.
Clindamycin: Offered as a vaginal cream or oral medication, clindamycin is another effective antibiotic option. The vaginal cream form is often preferred for individuals who experience gastrointestinal discomfort with oral antibiotics.
Tinidazole: Used primarily for recurrent cases, tinidazole is an oral antibiotic that functions similarly to metronidazole but may cause fewer side effects, such as nausea.

Supplementary Home Remedies

While antibiotics are the primary treatment, some lifestyle and dietary changes may help manage or prevent BV:

Probiotics: Consuming yoghurt with live cultures or taking probiotic supplements containing Lactobacillus strains can help restore a healthy vaginal microbiome.
Hydration and diet: Drinking plenty of water and maintaining a balanced diet rich in vitamins and nutrients can support overall vaginal health.
Avoid douching and scented products: Using douches, scented soaps, or vaginal sprays can disrupt the natural bacterial balance, increasing the risk of BV recurrence.
Wearing breathable underwear: Cotton underwear allows for better air circulation, reducing excessive moisture buildup that can promote bacterial imbalances.

How to Prevent Bacterial Vaginosis?

Practice safe sex

Using condoms during sexual activity can significantly help in minimizing the disruption of the vaginal pH. The vagina maintains a delicate pH balance, which is naturally acidic, and condoms act as a barrier against potential irritants, bacteria, and pathogens that can cause infections like trichomoniasis. By reducing direct contact with bodily fluids and introducing foreign substances into the vaginal area, condoms protect the vaginal flora and maintain its health.

It is important to remember that, apart from preventing STIs, condoms play a vital role in maintaining a stable vaginal environment, ensuring that harmful bacteria and yeast are less likely to thrive.

Limit antibiotic overuse

While antibiotics are essential for treating infections, overusing them can lead to an imbalance in the vaginal microbiome. The vagina is home to beneficial bacteria, primarily Lactobacilli, which help maintain the natural acidic pH and protect against harmful microbes. When antibiotics are taken unnecessarily or excessively, they may kill off these beneficial bacteria, leading to an overgrowth of yeast or harmful bacteria, increasing the risk of infections like yeast infections or bacterial vaginosis.

It is important to only take antibiotics when prescribed by a doctor and to follow the dosage guidelines carefully to help preserve the balance of good bacteria.

Choose breathable underwear

Wearing breathable, cotton underwear is a simple yet effective way to support vaginal health. Breathable fabrics allow air circulation, preventing moisture from building up in the vaginal area, which can create an environment conducive to the growth of bacteria or fungi.

Tight, non-breathable fabrics, such as those made from synthetic materials, can trap heat and sweat, increasing the risk of infections like yeast infections. By choosing cotton underwear, you allow the skin to breathe, which helps maintain the natural balance of bacteria and keeps the vaginal area dry and healthy.

Avoid scented soaps and vaginal sprays

Scented soaps, douches, feminine washes, and vaginal sprays are commonly used to mask odors and create a sense of cleanliness. However, these products can disrupt the natural bacterial balance in the vagina.

The vagina is self-cleaning, and it maintains its balance through the natural secretions that help to clear out dead cells and bacteria. The chemicals in scented products can irritate sensitive vaginal tissues and alter the pH balance, which can increase the risk of infections, irritation, or allergic reactions.

It is best to use mild, unscented soap for external genital care and avoid any douching or feminine washes unless specifically recommended by a doctor.

Conclusion

Bacterial vaginosis is a common yet often overlooked condition that affects many women. While it is not dangerous in itself, untreated BV can lead to complications, including increased susceptibility to STIs and pregnancy-related risks. Understanding the causes, symptoms, and treatment options allows for better management and prevention.

If you suspect BV, consult a doctor for diagnosis and treatment.

Frequently Asked Questions

Is bacterial vaginosis the same as a yeast infection?
No, bacterial vaginosis (BV) and yeast infections are different. BV is caused by an imbalance of bacteria in the vagina, whereas a yeast infection is caused by an overgrowth of yeast (Candida). While both conditions share similar symptoms, such as unusual discharge, BV is primarily a bacterial issue, while yeast infections are fungal.
Can BV go away on its own?
In some cases, BV may resolve without treatment, but it is not reliable. Untreated BV can increase the risk of complications like sexually transmitted infections (STIs) and preterm labour in pregnant women. Therefore, it’s important to seek medical advice if symptoms appear.
Can I get BV from my partner?
BV is not considered a sexually transmitted infection (STI), but sexual activity with new or multiple partners can increase the risk of developing BV. The condition is linked to an imbalance in the vaginal microbiome, which can be influenced by sexual contact.
Is BV contagious?
BV is not contagious in the traditional sense like some STIs, but certain behaviours, like having unprotected sex or multiple partners, may increase the risk of developing it. It is important to maintain good hygiene and communicate with your sexual partner(s) if symptoms arise.

Important

This blog, including its text, images, and infographics, is for educational purposes only and not a substitute for professional medical advice. For personalised advice, always consult a doctor.

References

US Centers for Disease Control and Prevention. Bacterial Vaginosis - CDC Fact Sheet. Accessed on 31 January 2025. https://dpbh.nv.gov/uploadedFiles/dpbh.nv.gov/content/Programs/STD/dta/Publications/Bacterial%20Vaginosis(2).pdf
Frontiers in Reproductive Health. Bacterial vaginosis: a review of approaches to treatment and prevention. 2023. https://pubmed.ncbi.nlm.nih.gov/37325243/
Microorganisms. Relationship between Bacterial Vaginosis and Sexually Transmitted Infections: Coincidence, Consequence or Co-Transmission? 2023. https://pmc.ncbi.nlm.nih.gov/articles/PMC10609101/
Obstetrics and Gynaecology. Bacterial vaginosis in early pregnancy and pregnancy outcome. 1992. https://pubmed.ncbi.nlm.nih.gov/1635726/