Introduction
Bacterial vaginosis (BV) is a common vaginal condition caused by an imbalance of the usual vaginal bacteria—typically a drop in protective Lactobacillus species and overgrowth of other anaerobes. It is not classified as a classic sexually transmitted infection, though sexual activity can influence risk.
Many people notice a thin gray or white discharge with a fishy odour that is stronger after sex. Itching or irritation can occur, but some have few symptoms and still need treatment when BV is found, especially in pregnancy or before certain procedures.
Douching, scented hygiene products, new or multiple partners, smoking, and high sugar diets are linked with higher risk. Men can carry organisms without symptoms but BV primarily affects people with a vagina, most often of reproductive age.
Diagnosis uses exam, vaginal pH, microscopy, and sometimes a whiff test. Antibiotics such as metronidazole or clindamycin usually clear symptoms, though recurrence is common. This page is general education; personal plans come from a clinician.
Overview
BV reflects disrupted vaginal microbiome ecology rather than a single contagious germ. It must be distinguished from yeast infection and trichomoniasis, which need different treatment.
Amsel criteria or Gram-stain scoring guide diagnosis in clinic. Untreated BV raises risk of STI acquisition, pelvic inflammatory disease, and pregnancy complications.
Most people improve within days of antibiotics; recurrent BV may need extended or maintenance strategies under clinical supervision.
- Vaginal microbiome imbalance, not a typical STI label
- Thin gray/white discharge and fishy odour are classic
- Risk rises with douching, smoking, and partner change
- Diagnosis: exam, pH >4.5, microscopy, whiff test
- Treat with metronidazole or clindamycin as prescribed
- Recurrence is common; pregnancy needs prompt treatment
What happens in the body
Healthy vaginal flora is often Lactobacillus-dominant and keeps pH low. When that community shifts, anaerobic bacteria thrive, raise pH, and produce amines that create the characteristic fishy smell.
The altered mucosa and microbiome can make it easier for sexually transmitted pathogens to establish infection and may facilitate ascending infection toward the uterus and fallopian tubes.
- Loss of Lactobacillus → higher vaginal pH
- Anaerobe overgrowth produces odorous amines
- Barrier and immune changes raise STI and PID risk
- Hormonal and behavioural factors can tip the balance again after treatment
Signs and symptoms
Symptoms range from none to bothersome discharge. Common possibilities include:
- Thin gray, white, or off-white vaginal discharge
- Fishy vaginal odour, often worse after intercourse
- Mild vaginal itching or irritation
- Burning with urination in some people
- Discomfort during sex
- Absence of thick cottage-cheese discharge typical of yeast (helps differentiate)
- Severe pelvic pain, fever, or heavy bleeding—warning signs of complications or another diagnosis
Causes and risk factors
BV follows microbiome disruption. Factors commonly considered include:
- New or multiple sexual partners (association, not simple “STI contagion”)
- Douching and scented soaps, sprays, or washes
- Smoking and high-stress lifestyles
- Diets high in sugar and ultra-processed foods
- Reproductive age (especially about 15–44 years)
- Diabetes or weakened immunity
- Recent antibiotic use that alters flora
- Possible family or host susceptibility in some studies
Diagnosis and evaluation
Clinical criteria separate BV from yeast and trichomoniasis:
- Symptom and sexual/reproductive history, including prior BV episodes
- Pelvic exam assessing discharge and vaginal appearance
- Vaginal pH testing (often >4.5 in BV)
- Microscopy of discharge for clue cells and flora pattern
- Whiff test with KOH for fishy amine odour
- STI testing when indicated to exclude co-infection
- Differentiate from candidiasis, trichomoniasis, chlamydia, and gonorrhea
Treatment and management
Prescription antibiotics restore balance for most people; finish the full course:
- Oral or vaginal metronidazole as directed by a clinician
- Clindamycin cream or oral clindamycin when appropriate
- Complete therapy even if odour and discharge improve early
- Avoid alcohol with metronidazole as advised on the label/clinical advice
- Partner treatment is not routinely required for BV, but discuss STI testing
- Pregnancy: treat promptly under obstetric guidance to reduce preterm-birth risk
- Recurrent BV may need longer regimens or specialist review—do not keep self-treating
Prevention, self-care, and lifestyle
Not every condition is fully preventable, but the steps below may lower risk or recurrence:
- Do not douche; clean externally with mild unscented products only
- Wear breathable cotton underwear; change out of damp clothes promptly
- Use condoms and limit partner change if recurrent BV is a problem
- Stop smoking; include yoghurt or other probiotic foods if tolerated
- Keep a balanced diet and manage blood sugar if diabetic
- Seek care early when odour and discharge return rather than waiting
Possible complications
Delay, missed care, or unsafe self-medication can raise the chance of complications in some cases:
- Higher susceptibility to STIs, including HIV
- Pelvic inflammatory disease
- Preterm birth, low birth weight, and postpartum infection in pregnancy
- Recurrent or chronic BV with ongoing discomfort
- Misdiagnosis delay if yeast or trichomoniasis is assumed without exam
- Relationship stress and reduced quality of life from persistent odour
When to see a doctor or seek emergency care
Seek prompt medical advice or emergency care if any of the following apply—it is safer not to wait and see:
- New fishy odour or unusual discharge that persists
- Severe pelvic pain or pain with intercourse
- Fever, chills, or feeling systemically unwell
- Heavy or unusual vaginal bleeding
- Symptoms in pregnancy or before gynaecological procedures
- BV that returns soon after finishing antibiotics
Living with the condition
Track triggers such as douching, new products, or partner change. Many people do well with prompt retreatment and prevention habits when BV recurs.
Take medicines exactly as prescribed and ask about vaginal versus oral options if side effects are hard to tolerate.
If you are pregnant or trying to conceive, mention any BV history early so screening and treatment can be planned.
Frequently asked questions
What are the main symptoms of bacterial vaginosis?
Thin gray or white discharge and a fishy odour are most typical. Mild itching can occur; severe pain or heavy bleeding needs prompt review.
How is BV diagnosed?
A clinician uses history, pelvic exam, vaginal pH, microscopy, and sometimes a whiff test. Home guessing often confuses BV with yeast infection.
Is bacterial vaginosis an STI?
BV is not classified as a classic STI, but sexual activity can influence risk. It is not simply “caught” like gonorrhea, yet condom use may help some people.
Can I treat BV at home without antibiotics?
Lifestyle steps help prevention, but confirmed BV usually needs prescription antibiotics. Delaying care can raise STI and pregnancy risks.
Can BV affect pregnancy?
Yes. BV in pregnancy is linked with preterm birth and other complications, so treatment under obstetric advice is important.
Why does BV keep coming back?
Recurrence is common because the microbiome can shift again. Ask your clinician about extended therapy, trigger review, and STI screening.
Important caution
This article is for general health education only. It is not personal medical advice, a prescription, or a substitute for pelvic examination.
Antibiotic choice in pregnancy, recurrence, or mixed infections should follow assessment by a qualified clinician.
If pelvic pain, fever, heavy bleeding, or pregnancy-related symptoms occur, seek medical care without delay.