Bacterial Vaginosis: Signs, Causes, Treatment & Prevention
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Introduction
Bacterial vaginosis symptoms causes treatment and prevention describes BV care here.
Bacterial vaginosis, or BV, is a common change in the vagina’s normal bacteria 1,2. Many people with BV notice no symptoms 2,7.
If symptoms occur, discharge and a fish-like odor are common signs 7,9. Antibiotics can treat BV, but the condition often returns 2,4.
This guide covers signs, causes, diagnosis, care, risk reduction, and repeat BV.
Overview: What Is Bacterial Vaginosis?
BV is vaginal dysbiosis, meaning the usual balance of vaginal germs has changed 2. Helpful *Lactobacillus* bacteria decrease, while several anaerobic bacteria increase 1,2.
Anaerobic bacteria can grow without oxygen. BV involves several bacterial types rather than one single germ 2,3.
How the vaginal microbiome normally works
The vaginal microbiome is the group of germs living inside the vagina 3. *Lactobacillus* bacteria often lead this group in a healthy vagina 2,3.
These helpful bacteria make lactic acid and hydrogen peroxide 2. They help maintain a healthy vaginal environment 1,2.
Many bacterial types can live in the vagina 3. One BV-linked germ can also appear in people without symptoms 3.
What changes when BV develops?
During BV, helpful lactobacilli lose their usual lead 2. Several anaerobic bacteria then grow in larger amounts 1,2.
These bacteria may include *Gardnerella*, *Prevotella*, and *Mobiluncus* species 1,2. A layer of germs can also form on vaginal cells 2.
This layer is called a biofilm. The bacterial change can be brief or remain for longer periods 2.
BV is not generally classed as a sexually transmitted infection, or STI 5. However, sexual activity can affect BV risk 7,9.
BV can occur without sexual activity 7. It rarely affects people who have never had sex 2,7.
How common is BV?
BV is a leading cause of vaginal discharge during the reproductive years 1,2. It is also the most common vaginal condition among women ages 15 to 44 7.
A global review cited by WHO estimated BV rates between 23% and 29% 1. The review covered women of reproductive age 1.
Rates differ between countries and population groups 1. BV occurs worldwide and has a higher burden in lower-resource settings 1.
Many people with BV do not know they have it 2,7. BV occurs more often among people who are sexually active 7,8.
Symptoms and Warning Signs
BV symptoms can resemble signs of a yeast infection or STI 8,9. Symptoms alone cannot confirm the cause 8,9.
An examination and vaginal fluid test can help identify BV 7,9.
Common discharge, odor, and irritation symptoms
If BV causes symptoms, discharge may look thin, smooth, white, or gray 7,9. Some people may notice a green shade 8,9.
The discharge may coat the vaginal walls in an even layer 2. It may also have a milk-like texture 2.
A strong fish-like odor is another common BV sign 7,8,9. The odor may become more noticeable after sex 7,9.
Other possible BV symptoms include the following changes:
If itching occurs, it may affect the vagina or nearby outer skin 7,8.
If irritation develops, the vaginal area may feel uncomfortable 1,9.
If burning occurs during urination, BV may be one possible cause 7,8.
If vaginal pain occurs, a clinician can check for other causes 7,9.
These symptoms can also occur with other vaginal conditions 8,9. A clinician can use examination findings and testing to tell them apart 7,9.
BV compared with yeast infections and STIs
A yeast infection often causes thick, white discharge 4,9. It may resemble cottage cheese and usually lacks a strong odor 9.
Yeast infections often cause more itching than BV 9. However, overlapping symptoms make self-diagnosis difficult 8,9.
Some STIs can also resemble BV 8. Testing may be helpful after a new sexual exposure because symptoms can look alike 8.
Yeast medicines do not treat BV 1,9. Antifungal medicines treat yeast, while antibiotics treat BV symptoms 1,7.
Avoid choosing treatment based only on discharge or odor. The wrong medicine may delay proper assessment.
Why diagnosis matters
Discharge can also result from yeast or trichomoniasis 1,5. Trichomoniasis is an STI caused by a parasite 5.
Recent sex or a menstrual period can affect a BV assessment 1. Douching and recent germ-killing medicines can also affect test results 1.
Tell the clinician about these factors during the visit. This information may help with test choices and result review.
If yeast self-care does not work, arrange an examination 8. A clinician can check for BV and other causes 7,9.
Causes and Risk Factors
The exact event that starts BV remains unknown 1,2. BV develops when the vaginal bacterial balance shifts 2.
This change does not mean someone caused their condition. BV can occur across different habits and sexual histories 7,8,9.
The bacterial imbalance behind BV
BV develops as helpful lactobacilli decrease and anaerobic bacteria increase 2,3. Several bacterial types may increase at the same time 1,2.
Experts once linked BV mainly with *Gardnerella vaginalis* 3. Experts now recognize that BV involves many anaerobic bacteria 2,3.
Some vaginal bacterial changes last only a short time 2. Other changes may remain for longer periods 2.
The exact trigger for this shift is unclear 1,2. No single germ explains every case 2,3.
Sexual and personal risk factors
BV is linked with sexual activity, but it is not classed as an STI 5,7. These links do not place blame on anyone.
Factors associated with BV include these behaviors or changes:
Douching can upset the usual balance of vaginal bacteria 1,2,7.
A new sexual partner is linked with increased BV risk 2,7,8.
Having several sexual partners is also linked with BV 2,7,8.
Not using condoms is linked with increased risk 2,7.
Placing herbs inside the vagina can increase BV risk 1.
Some vaginal hygiene products can disturb the vaginal environment 1,3.
BV is more common among women with female partners 8.
BV rates can increase during menstrual periods 2.
BV can still occur without a known risk factor. It can also develop without sexual activity 7.
Common myths about BV
BV does not come from toilet seats, bedding, or swimming pools 7. It also does not spread through contact with a used surface 9.
Douching does not protect against BV 7,8. Instead, it can disturb the vagina’s normal bacterial balance 7,8.
The vagina cleans itself and does not need washing inside 8. Normal bathing is enough for the outer genital area 8.
Scented products may irritate vaginal tissue 8. Inserted herbs and other products can also increase BV risk 1.
Diagnosis and Treatment
A clinician can diagnose BV through your health history, an examination, and fluid tests 1,9. These steps help separate BV from yeast and some STIs 1,8.
How clinicians test for BV
A clinician may ask about discharge and past vaginal infections 1,9. Questions may also cover sexual history and recent vaginal products 1.
During an examination, the clinician may look for unusual discharge 1,9. They may collect vaginal fluid with a swab 7,9.
The sample may undergo several types of testing:
A wet mount uses a microscope to inspect vaginal fluid 1,9.
A pH test measures how acidic the vaginal fluid is 1,2.
A whiff test checks for a fish-like odor 2,9.
A Gram stain shows the types and amounts of bacteria 2.
Some molecular tests find genetic material from BV-linked bacteria 2.
Clinicians may use four findings called the Amsel criteria 2. A clinical BV diagnosis requires at least three of these findings 2.
The four Amsel findings are listed below:
Thin, even discharge coats the vaginal walls 2.
Vaginal fluid has a pH above 4.5 2.
A microscope shows clue cells in the fluid 2.
A whiff test produces a fish-like smell 2.
Clue cells are vaginal cells covered with attached bacteria 2. The whiff test may use a solution that brings out the odor 2.
A vaginal Gram stain is the reference laboratory method for diagnosing BV 2. It shows the balance between lactobacilli and BV-linked bacteria 2.
Clinicians can grade the sample with a Nugent score 2. Scores from zero through three suggest a lactobacilli-rich pattern 2.
Scores from four through six show an intermediate pattern 2. Scores from seven through ten support a BV diagnosis 2.
Selected molecular tests can help diagnose BV in people with symptoms 2. These tests detect genetic signs from specific vaginal bacteria 2.
Antibiotic treatment options
Antibiotics can treat BV symptoms 4,7. Metronidazole and clindamycin are common treatment choices 1,4.
These medicines may come as oral or vaginal products 1,4. A clinician can select the form that fits the treatment plan.
Tinidazole and secnidazole are other possible choices in some settings 1. Treatment length can vary by medicine and form 4.
Safe antibiotic use includes these important steps:
Take or use each dose as directed by the clinician 4,7.
Complete the full course, even if symptoms improve early 4,7.
Do not stop the medicine early without medical advice 4.
Avoid yeast medicine unless the cause of symptoms is clear 1,8.
Avoid douching and inserted herbs during BV treatment 1.
Report new symptoms rather than assuming BV has returned 4,8.
Stopping antibiotics early can allow resistant bacteria to develop 4. Completing the course supports the prescribed care plan 4,7.
Antibiotics can sometimes lead to a yeast infection 4. If this occurs, itching and thick white discharge may develop 4.
Metronidazole tablets can cause a metal-like taste, nausea, or vomiting 4. Discuss medicine concerns with the prescribing clinician.
Home products and probiotics
Douching cannot replace medical BV treatment 1,7. It can disturb bacteria that support vaginal health 7,8.
Inserted herbs and hygiene products can increase BV risk 1. Avoid using these products as home treatments.
Research has not proved that lactic acid bacteria improve BV treatment results 4. These products are sometimes sold as probiotics.
Evidence supporting probiotics remains limited 4. Ask a clinician before adding them to a BV care plan.
Pregnancy, follow-up, and repeat BV
BV during pregnancy is linked with early birth and low birth weight 7. WHO also links untreated BV with harmful pregnancy outcomes 1.
If BV symptoms occur during pregnancy, contact a pregnancy care clinician 8. The clinician can test the discharge and choose suitable care 7,8.
Antibiotics can be used for BV during pregnancy 4. The treating clinician should choose the medicine and treatment plan.
BV often returns after treatment 2,4. About half of women may have symptoms again one year later 4.
Repeat symptoms need another assessment. Similar symptoms can come from BV, yeast, or other vaginal conditions 8,9.
Partner management advice continues to change 2,3,6. CDC guidance says male partner treatment has not prevented recurrence 2.
A 2025 clinical review reports newer ACOG advice for some recurrent cases 3. Ask the clinician to verify the latest partner guidance 2,3,6.
Prevention, Recurrence, and Health Risks
The exact cause of BV remains unknown 1,2. However, some choices may reduce known risk factors 7,8.
How to prevent bacterial vaginosis
The following habits may help lower BV risk:
Avoid douching because it can disturb helpful vaginal bacteria 7,8.
Avoid scented washes and soaps near the genital area 8.
Choose unscented tampons or pads when possible 8.
Do not place herbs or hygiene products inside the vagina 1.
Use condoms correctly whenever you have sex 7.
Consider limiting new or multiple sexual partners 7,8.
Clean sex toys before and after use 8.
Wash the outer genital area gently with warm water 8.
These steps address known risk factors. However, researchers do not fully understand how to prevent BV 7.
What to do when BV keeps returning
Repeat BV is common after recommended treatment 2,4. Symptoms may return within weeks 4.
A bacterial biofilm may play a role in repeat BV 2,6. The healthy vaginal bacterial mix may also fail to return 6.
If symptoms return, arrange another assessment. Yeast and other vaginal conditions can cause similar symptoms 8,9.
Do not keep treating presumed BV without a diagnosis. A clinician can test for BV and other possible causes 7,9.
Ask about current options for repeat BV. Guidance about partner care should be checked because newer advice may differ 2,3,6.
Possible health risks linked with BV
BV is linked with an increased chance of getting several STIs 2,7,8. These include HIV, chlamydia, gonorrhea, and trichomoniasis 2,7.
BV can also increase the chance of passing HIV to a partner 1,2. It is linked with pelvic inflammatory disease, called PID 1,8.
PID affects the uterus and fallopian tubes 8. It can raise the risk of fertility problems 8.
BV may increase infection risk after some gynecologic procedures 2,8. These procedures include hysterectomy and dilation and curettage 8.
Pregnancy risks can include early birth and low birth weight 7. WHO also reports links with spontaneous abortion and preterm delivery 1.
When to See a Doctor
If discharge smells unusual and causes discomfort, make a healthcare appointment 8. Testing can check for BV and other possible causes 7,8,9.
Arrange professional care in any of these situations:
If symptoms occur during pregnancy, contact your pregnancy care clinician 8.
If discharge differs from past infections, arrange an assessment 8.
If symptoms follow a new sexual exposure, ask about testing 8.
If yeast self-care fails, contact a healthcare professional 8.
If symptoms return after antibiotics, request another assessment 2,4.
If symptoms continue, avoid repeated self-treatment without guidance 8.
Many vaginal conditions share similar symptoms 8,9. An accurate diagnosis helps the clinician choose suitable treatment 7,9.
Conclusion
Knowing BV signs, causes, treatment, and prevention can help you respond to vaginal changes. Testing is more reliable than guessing from discharge or odor alone 7,8,9.
Antibiotics can treat BV symptoms 4,7. However, BV often returns and may require another assessment 2,4.
If symptoms occur during pregnancy, contact a healthcare professional 8. New exposure, failed self-care, and repeat symptoms also warrant medical review 2,4,8.
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