Medical note: Symptoms can suggest bacterial vaginosis (BV), but they cannot confirm it. A fishy smell or changed discharge can also occur with an STI or another vaginal condition. Speak with a GP or sexual health clinic if you think you have BV, particularly if this is your first episode, you are pregnant, symptoms followed sex with a new partner, or the pattern is unusual for you.
Key takeaways
- The classic BV pattern is a strong fishy smell with thin, greyish-white or watery discharge. The smell may be more noticeable after sex.
- About half of women with BV have no symptoms. No odour or discharge change does not necessarily rule it out.
- BV does not usually cause significant itching or soreness. Prominent itch, thick white discharge, sores, pelvic pain or bleeding points towards another possible cause that needs assessment.
- BV is not classed as an STI, but sexual activity can affect risk and symptoms can overlap with an STI. A sexual health clinic can test for both.
- Symptoms and a home pH test are not a diagnosis. A clinician may use your history, an examination and a vaginal swab or other tests.
- Symptomatic BV is commonly treated with prescribed antibiotics. Supplements, deodorants, douches and intimate washes should not replace assessment or treatment.
What are the symptoms of bacterial vaginosis?
When BV causes symptoms, the most recognisable combination is a strong fishy vaginal smell and a thin, watery discharge that may look greyish-white. The smell can be more obvious after sex. BV usually does not cause marked itching or soreness, although symptoms do not follow a perfect rule in every person.
The other important fact is that BV can be silent. The NHS says around half of women with BV do not notice symptoms. You therefore cannot confirm or exclude BV from smell, discharge colour, discomfort or a home test alone.
BV is usually treatable, but a changed smell or discharge deserves the correct explanation. Trichomoniasis and other sexually transmitted infections (STIs), thrush, irritation, hormonal dryness and a retained object such as a tampon can create overlapping symptoms. A clinician can confirm the cause instead of asking you to choose between lookalike conditions.
For the wider explanation of recurrence, the vaginal microbiome and treatment options, use Ellasie’s bacterial vaginosis guide. This article stays focused on recognising symptoms and choosing the right next step.
BV is not a hygiene failure. Washing more aggressively will not diagnose or treat it. Douching, vaginal deodorants and fragranced intimate products may disturb or irritate the vaginal environment.
What is bacterial vaginosis?
Bacterial vaginosis is a change in the balance of bacteria in the vagina. It is often described as vaginal dysbiosis: Lactobacillus-dominant bacteria become less prominent and a more diverse group of anaerobic bacteria becomes abundant. That shift can change vaginal acidity and produce the characteristic discharge and odour.
BV is common and is not classed by the NHS as an STI. Sexual activity can still trigger it or play a role in transmission, and BV is associated with factors such as a new partner. It can also occur in people who have not had sex. This distinction matters: having BV is not proof that a partner has been unfaithful, and it is not evidence that someone is unclean.
The bacterial change is different from vaginal thrush, which is caused by an overgrowth of Candida yeast. It is also different from trichomoniasis, which is an STI caused by a parasite. Because all three can affect discharge, guessing from one symptom can lead to the wrong treatment.
What are the main BV symptoms?
Strong fishy vaginal odour
A pronounced fishy smell is the symptom most strongly associated with BV. It may be noticed in discharge, underwear or during sex and can become more obvious after sex. A fishy smell is a useful clue, not proof: trichomoniasis can also cause unpleasant or fishy-smelling discharge.
Try to distinguish an odour in vaginal discharge from an external sweaty smell around the vulva or groin. Both may end up on underwear, but they do not necessarily have the same cause. Do not insert soap, deodorant or fragrance to test whether the smell disappears.
Thin, greyish-white or watery discharge
BV discharge is commonly described as thin, watery and greyish-white. It may coat the vaginal walls rather than forming thick clumps. Some people notice more discharge than usual, while others mainly notice the smell.
Normal discharge can also be clear or white and may become wetter or more noticeable around ovulation, during pregnancy, with sexual activity or when using contraception. The change from your own normal pattern is often more useful than judging one colour in isolation.
Little or no itching and soreness
The NHS says BV does not usually cause soreness or itching. Mild irritation or burning can occur in some descriptions of BV, but strong itch, visible inflammation, cracked skin or marked soreness is not the classic pattern. Those symptoms make thrush, dermatitis, an irritant reaction or another cause important to consider.
Can you have BV without symptoms?
Yes. Around half of women with BV have no symptoms according to the NHS, and the US Centers for Disease Control and Prevention also notes that most women with BV in a nationally representative survey were asymptomatic.
This does not mean everyone needs routine home testing. Whether an asymptomatic bacterial pattern needs treatment depends on the situation, including pregnancy, planned procedures, test findings and local clinical guidance. A result should be interpreted by the professional who arranged the test rather than treated from an online checklist.
It also means a partner can have no obvious symptoms. If a sexual health clinician recommends partner assessment or treatment, follow that individual advice. Do not share prescriptions or use leftover antibiotics.
Which symptoms are not typical of BV?
The following do not rule BV out, but they make another or additional cause more likely:
- intense itching or vulval irritation;
- thick, white, cottage-cheese-like discharge;
- yellow-green or frothy discharge;
- blisters, ulcers, sores or a new rash;
- significant pain when urinating or during sex;
- pelvic or lower-abdominal pain;
- bleeding between periods or after sex;
- fever, chills, vomiting, faintness or feeling very unwell.
If itching or dryness is the main concern, read about causes of vaginal dryness and itching and arrange an assessment when symptoms are new, persistent or uncertain. Treating every itch as thrush or every smell as BV can delay the right diagnosis.
BV, thrush, trichomoniasis or irritation: how do the patterns compare?
This table helps organise symptoms; it is not a diagnostic tool. More than one condition can occur at the same time, and an STI may cause few or no symptoms.
| Pattern | Discharge or odour | Other clues | Next step |
|---|---|---|---|
| Possible BV | Thin, watery, greyish-white discharge; strong fishy smell, sometimes more noticeable after sex | Usually little or no itching or soreness; many people have no symptoms | See a GP or sexual health clinic to confirm the cause and rule out an STI |
| Possible thrush | White, thick or cottage-cheese-like discharge that does not usually smell | Itching, irritation, soreness or stinging during sex or urination | Ask a pharmacist about a familiar, previously diagnosed episode; use a GP for a first, recurrent, severe or uncertain episode |
| Possible trichomoniasis or another STI | Yellow-green, frothy or unpleasant-smelling discharge; trichomoniasis may smell fishy | Pain when urinating or having sex, itching, soreness, swelling or lower-tummy pain; symptoms may also be absent | Contact a sexual health clinic or GP for testing, especially after sex with a new partner |
| Possible irritation or hormonal dryness | Discharge may be unchanged; symptoms can begin after a new soap, wipe, lubricant or fragranced product | Dryness, burning, soreness, itching or pain during sex | Stop the possible irritant and seek advice if symptoms persist, are significant or the cause is unclear |
| Possible pelvic infection or another urgent cause | Discharge may look or smell unusual but is not diagnostic | Pelvic pain, bleeding, fever, chills, vomiting, faintness or feeling very unwell | Seek urgent medical advice; severe or worsening symptoms may require A&E |
What causes BV, and who is more likely to get it?
BV begins with a change in the natural balance of vaginal bacteria, but the exact trigger is not always identifiable. Risk factors and associations are not guarantees: someone can have several and never develop BV, while another person can develop it without an obvious reason.
Factors associated with BV include:
- sexual activity, including a new partner or multiple partners;
- not using condoms;
- sex with a partner who has a vagina and may share BV-associated bacteria;
- douching or using perfumed products in or around the vagina;
- having an intrauterine device (IUD), according to NHS guidance;
- menstrual timing, with prevalence reported to increase during menstruation;
- smoking.
BV can happen without sexual activity, so it is inaccurate to describe every case as sexually transmitted. At the same time, “not an STI” should not be used to dismiss testing: discharge and odour can be caused by an STI, and a clinician may need to rule that out.
How is bacterial vaginosis diagnosed?
A GP or sexual health clinician will usually ask about the discharge, odour, discomfort, menstrual timing, pregnancy, medicines, intimate products and sexual history. They may examine the vagina and take a swab to assess BV and other infections.
Clinical diagnosis can use a combination of findings rather than one symptom. The CDC describes the Amsel criteria, which consider the appearance of discharge, vaginal pH above 4.5, a characteristic odour test and “clue cells” seen under a microscope. Laboratory or point-of-care tests may also be used.
A home vaginal pH strip cannot diagnose BV. A raised pH can support a clinician’s assessment, but it cannot show why the pH changed or distinguish BV from every STI or other cause. A normal result also should not overrule concerning symptoms.
Ellasie’s medical review policy explains why symptom-led health content must show its diagnostic limits. An online guide can help you describe the pattern; it cannot examine, swab or test you.
What should you do if you notice possible BV symptoms?
- Note what changed. Record the smell, discharge colour and texture, itching, pain, bleeding, menstrual timing, recent sex, pregnancy possibility, medicines and any new products.
- Do not douche or mask the smell. Avoid vaginal deodorants, fragranced wipes, internal washes and antiseptics. Wash only the external vulval area gently.
- Choose the right service. A GP or sexual health clinic can assess possible BV and rule out an STI. Sexual health services are confidential and often provide testing without a GP referral.
- Mention STI risk openly. Tell the clinician about a new partner, sex without condoms or other exposure that changes which tests are useful.
- Follow the diagnosis-specific treatment. Do not combine antifungals, antibiotics, boric acid, pH products and supplements by guesswork.
- Return if the pattern persists or changes. Failed treatment can mean recurrence, reinfection, an incorrect initial assumption or more than one condition.
Do not use a supplement to treat suspected active BV. Evidence for probiotics is strain-, product- and outcome-specific, and recommendations differ. If you want the separate evidence review after diagnosis and treatment have been addressed, read what the evidence says about probiotics for BV.
How is BV treated, and what if it comes back?
The NHS says BV is usually treated with antibiotic tablets, gels or creams prescribed by a GP or sexual health clinic. The best option depends on your diagnosis, pregnancy status, medical history, allergies, previous treatment and local guidance. Use the medicine exactly as directed and follow any advice about sex, condoms or vaginal products during treatment.
Symptoms improving does not confirm that every possible infection has been treated. Do not use another person’s medicine, repeat an old prescription without advice or stop a prescribed course early unless a clinician tells you to.
BV commonly returns, sometimes within a few months. Recurrence is not evidence that you failed to wash properly. Contact a GP or sexual health clinic if symptoms return rather than repeating self-treatment indefinitely. The clinician can confirm whether it is BV again, look for other causes or triggers and discuss a longer-term plan when appropriate.
Partner advice is not one-size-fits-all. The current NHS page says a partner who is a woman or has a vagina may also need treatment. Recommendations can depend on partner anatomy, symptoms, recurrence and local practice, so ask the treating clinic rather than sharing treatment.
What should you do about BV symptoms during pregnancy?
Contact your midwife, GP, maternity unit or sexual health clinic if you are pregnant and think you have BV or notice unusual discharge or odour. The NHS advises seeking treatment because BV carries a small chance of pregnancy complications.
Pregnancy itself can increase normal discharge, which is usually clear or white and does not have a strong unpleasant smell. That normal change makes assessment—not guesswork—more important when the smell, colour or texture becomes unusual, or when there is pain, bleeding, fever or concern about fluid loss.
Do not insert an unprescribed remedy, use leftover antibiotics or assume a product labelled “natural” is suitable in pregnancy. Tell the clinician about every medicine, supplement and vaginal product you have used.
When should you see a GP or sexual health clinic?
Arrange assessment if:
- you think you have BV or this is your first episode;
- your discharge changes in smell, colour, texture or amount;
- a strong or fishy smell persists;
- symptoms started after sex with a new partner or an STI is possible;
- there is itching, soreness, pain when urinating or pain during sex;
- you bleed between periods or after sex;
- symptoms return, differ from previous episodes or do not improve after treatment;
- you are pregnant or may be pregnant;
- you have diabetes, a weakened immune system or another condition that changes treatment safety.
Seek urgent advice from NHS 111 or an urgent GP service for pelvic or lower-abdominal pain, especially during pregnancy, or if symptoms include fever, chills, vomiting or feeling very unwell. Call 999 or go to A&E for severe or worsening pelvic pain, sudden intense lower-abdominal pain, pelvic pain with heavy bleeding, faintness or another medical emergency.
The bottom line
The clearest BV symptom pattern is fishy-smelling, thin greyish-white discharge, often without much itching or soreness. Yet half of women with BV may have no symptoms, and no smell, colour or home pH result can confirm the diagnosis.
Use symptoms to decide what to do, not to prescribe yourself a treatment. A GP or sexual health clinic can distinguish BV from thrush, trichomoniasis, another STI, irritation, hormonal dryness and other causes. Get checked promptly during pregnancy, after a new sexual exposure, when symptoms recur or when pain, bleeding, fever or feeling unwell changes the safety picture.
Frequently asked questions
What does BV discharge look and smell like?
BV discharge is commonly thin, watery and greyish-white, with a strong fishy smell that may be more noticeable after sex. Appearance and smell alone cannot confirm BV because other infections can overlap.
Can you have BV without a fishy smell?
Yes. Around half of women with BV have no symptoms, so BV may be present without a noticeable smell or discharge change. Whether testing is needed depends on symptoms, pregnancy, procedures and clinical context.
Does BV cause itching?
BV does not usually cause significant itching or soreness. Strong itch with thick white, usually non-smelly discharge is more typical of thrush, while irritation, skin conditions and other infections can also itch. Get advice when the cause is uncertain.
Is BV a sexually transmitted infection?
The NHS does not class BV as an STI, and it can occur without sex. Sexual activity can trigger it or play a role in transmission, however, and symptoms can resemble an STI. Testing may therefore be appropriate after sex with a new partner.
Can a home pH test tell whether I have BV?
No. Vaginal pH above 4.5 is one possible diagnostic clue, but a home strip cannot identify the cause or rule out an STI. Clinical diagnosis may use symptoms, examination, microscopy, a swab or another test.
When are BV-like symptoms urgent?
Fishy discharge alone is not usually an emergency, but pelvic pain, heavy bleeding, fever, chills, vomiting, faintness, severe worsening pain or feeling very unwell needs urgent assessment. Pregnancy with pain, bleeding or unusual discharge also needs prompt advice.
References and further reading
- NHS: Bacterial vaginosis — symptoms, diagnosis, treatment, recurrence and pregnancy advice
- NHS: Vaginal discharge — normal patterns, possible causes and when to get help
- NHS: Vaginitis — symptoms, causes and assessment
- NHS: Thrush in men and women — symptoms and treatment
- NHS: Trichomoniasis — symptoms, testing and treatment
- NHS: Pelvic inflammatory disease — symptoms and urgent advice
- US CDC: Bacterial vaginosis — diagnosis and treatment guidelines