Bacterial Vaginosis (BV): Symptoms, Causes & Treatment

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Bacterial Vaginosis (BV): Symptoms, Causes & Treatment

Bacterial vaginosis, usually shortened to BV, is a common vaginal condition caused by a change in the balance of bacteria that normally live in the vagina.

BV often causes a thin white or grey discharge and a noticeable fishy smell, although many people have no symptoms at all.

It isn’t the same as vaginal thrush and it isn’t managed exactly like a traditional sexually transmitted infection such as chlamydia. However, our understanding of BV has changed. Current Australian guidance recognises that BV-associated bacteria can be sexually transmitted between partners and that treating an ongoing sexual partner can reduce recurrence in some relationships.

The good news is that BV can usually be treated effectively with antibiotics, although recurrence is common.

Key takeaways

  • BV happens when the usual vaginal bacterial community changes and bacteria associated with BV become more dominant.
  • Common symptoms are a thin white or grey discharge and a strong fishy odour.
  • Many people with BV have no symptoms.
  • BV is different from thrush and can also resemble some sexually transmitted infections.
  • Sexual activity plays an important role in BV, particularly recurrence.
  • Current Australian guidance recommends treating an ongoing or regular partner with a penis at the same time as the person with BV.
  • Partners with a vagina should be offered testing because BV is highly concordant between partners.
  • Menstrual cups have not been shown to increase the risk of BV when used appropriately.
  • Douching and internal vaginal cleaning should be avoided.

On this page

What is bacterial vaginosis?

A healthy vagina contains a community of different bacteria.

In many people, Lactobacillus species are particularly important because they help maintain an acidic vaginal environment.

With bacterial vaginosis, Lactobacillus levels tend to decrease while other bacteria associated with BV become more abundant.

This shift in the vaginal microbiome can change vaginal pH and produce the characteristic discharge and odour associated with BV.

BV is better described as a vaginal dysbiosis, or imbalance in the vaginal bacterial community, rather than simply an infection caused by one particular bacterium.

What are the symptoms of bacterial vaginosis?

Many people with BV have no symptoms.

When symptoms do occur, they commonly include:

  • thin or watery vaginal discharge
  • white or greyish discharge
  • a strong or fishy vaginal smell

The odour can sometimes become more noticeable after sex or during menstruation because changes in vaginal pH can make the smell more apparent.

Significant itching, redness or soreness are less typical of BV. If itching or irritation is your main symptom, vaginal thrush, dermatitis or another cause may also need to be considered.

Read our guide to vaginal discharge and how it changes for more information about what can be normal and what is worth checking.

BV vs thrush and STIs

BV, vaginal thrush and sexually transmitted infections can sometimes cause similar changes in vaginal discharge, so symptoms alone aren’t always enough to identify the cause.

Condition Common signs
Bacterial vaginosis Thin white or grey discharge and a fishy smell, often without significant itching
Vaginal thrush Itching, burning, vulval irritation and often thick white or clumpy discharge
Trichomoniasis May cause yellow or green discharge, odour, irritation or pain
Chlamydia or gonorrhoea Often no symptoms but may cause abnormal discharge, pelvic pain or bleeding

 

A useful rule of thumb is that BV tends to be more about odour and thin discharge, while thrush tends to be more about itching, burning and vulval irritation. But real symptoms don’t always follow textbook descriptions.

If your symptoms are new or you aren’t sure whether you have BV or thrush, getting tested is more useful than repeatedly trying different over-the-counter treatments. 

What causes bacterial vaginosis?

There isn’t one single cause of BV.

Several factors are associated with a greater likelihood of developing it, including:

  • having a new sexual partner
  • having more than one sexual partner
  • sex without condoms
  • having sex with a partner who also has a vagina
  • douching or washing inside the vagina
  • using a copper IUD, particularly in people who experience recurrent BV

BV can also occur in people who aren’t currently sexually active, so sexual activity isn’t the only factor involved.

Does douching cause BV?

Douching is strongly associated with BV and should be avoided.

Washing inside the vagina can disturb the vaginal environment and isn’t necessary for hygiene.

The vagina naturally cleans itself through normal secretions.

Read more in our guide to douching and vaginal health.

Is bacterial vaginosis sexually transmitted?

This is where the advice around BV has changed.

BV has traditionally been described as “not an STI” because it isn’t caused by one single sexually transmitted pathogen and routine contact tracing isn’t used in the same way as it is for infections such as chlamydia or gonorrhoea.

However, current evidence shows that BV-associated bacteria can be exchanged between sexual partners and that reinfection from an ongoing partner is an important reason BV can recur.

Australian STI Guidelines now state that BV is sexually transmissible.

That doesn’t mean anyone has done anything wrong or that BV automatically indicates infidelity.

The bacteria involved can be shared between partners and remain present without causing obvious symptoms.

How is bacterial vaginosis diagnosed?

Your doctor or sexual health clinician will usually ask about your symptoms, vaginal discharge, sexual history and any previous episodes of BV.

Diagnosis may involve:

  • looking at the appearance of vaginal discharge
  • checking vaginal pH
  • assessing vaginal odour
  • examining vaginal fluid under a microscope
  • taking a vaginal swab

A swab doesn’t always need to be collected by the clinician. In some situations, self-collected vaginal samples may be offered.

Testing can also help distinguish BV from thrush, trichomoniasis and other causes of vaginal discharge or irritation.

If there is a possibility of an STI, your healthcare professional may recommend additional testing.

How is bacterial vaginosis treated?

Symptomatic BV is usually treated with antibiotics.

Australian treatment options include:

  • oral metronidazole
  • metronidazole vaginal gel
  • clindamycin vaginal cream

Other antibiotic regimens may be used when these treatments aren’t suitable.

Your doctor will recommend the option that best suits your circumstances, including pregnancy, breastfeeding, previous treatment and whether BV keeps returning.

Complete the prescribed course even if the smell or discharge improves sooner.

Antifungal treatments used for vaginal thrush don’t treat BV because BV is caused by changes in vaginal bacteria rather than Candida yeast.

Do probiotics treat BV?

Probiotics are widely promoted for vaginal health and recurrent BV.

Some research is promising, particularly around particular Lactobacillus strains, but products vary enormously and Australian STI Guidelines currently consider the evidence insufficient to routinely recommend vaginal probiotics as treatment for BV.

The same applies to intravaginal lactic-acid products.

That doesn’t mean nobody finds these products useful, but they shouldn’t replace recommended antibiotic treatment when BV needs treatment.

Do sexual partners need treatment for BV?

Current Australian guidance has changed substantially in this area.

Partners with a penis

If you have an ongoing or regular partner with a penis, Australian STI Guidelines now recommend treating that partner at the same time you are treated for BV.

This follows Australian research showing that treating both partners substantially reduced recurrence compared with treating the person with BV alone.

Partner treatment involves a combination of oral and topical antibiotics prescribed by a healthcare professional.

Both partners should complete treatment at the same time and avoid unprotected penile-vaginal sex during the treatment period.

Partners with a vagina

BV and BV-associated bacteria are also highly concordant between partners who both have vaginas.

There haven’t yet been clinical trials testing routine treatment of an asymptomatic partner with a vagina.

Current Australian guidance recommends offering the partner testing and treating them if BV is detected.

Why does bacterial vaginosis keep coming back?

Recurrence is one of the most frustrating parts of BV.

Even after successful antibiotic treatment, BV can return within weeks or months.

Possible reasons include:

  • re-exposure to BV-associated bacteria from an untreated sexual partner
  • difficulty re-establishing a Lactobacillus-dominant vaginal microbiome
  • douching or internal vaginal cleaning
  • other individual vaginal microbiome factors
  • in some people, use of a copper IUD

If symptoms keep coming back, don’t automatically assume every episode is BV.

Thrush, other forms of vaginitis and some vulval skin conditions can cause overlapping symptoms, and repeated antibiotic or antifungal treatment without confirming the diagnosis can make things more confusing.

If BV keeps returning, see your doctor rather than repeatedly self-treating.

Options for recurrent BV may include longer courses or suppressive antibiotic treatment, and partner treatment should also be considered where appropriate.

Bacterial vaginosis and pregnancy

BV during pregnancy has been associated with an increased risk of complications including premature birth and some pregnancy infections.

This doesn’t mean having BV means you will have a pregnancy complication.

Australian guidance recommends treating symptomatic BV during pregnancy.

Routine screening and treatment of people with no symptoms isn’t generally recommended in low-risk pregnancies.

If you’re pregnant and notice an unusual vaginal discharge or smell, mention it to your GP, midwife or maternity healthcare provider rather than assuming it is BV or thrush.

Can menstrual cups cause bacterial vaginosis?

Current evidence doesn’t suggest that menstrual cups increase the risk of bacterial vaginosis when they are used appropriately.

A 2019 systematic review of menstrual cup safety found no evidence that cups adversely affected vaginal flora overall.

More recent research has also been reassuring. A 2026 systematic review and meta-analysis involving more than 10,000 participants found no increased risk of BV among menstrual cup users. In pooled data, BV was actually less common among cup users, although the quality of the available studies varied.

That doesn’t mean menstrual cups prevent BV, but there is no good evidence that appropriately used cups cause it.

Good menstrual cup hygiene still matters.

Wash your hands before insertion and removal and clean your cup according to the manufacturer’s instructions.

You don’t need to use strongly fragranced soaps or antibacterial products, and any cleanser used on a cup should rinse away thoroughly.

If you’re being treated for BV and use a cup or disc, clean the product carefully according to its instructions before using it again.

What if my menstrual cup smells?

A noticeable fishy smell on menstrual fluid collected in your cup may be one sign that your vaginal discharge has changed, particularly if you also notice thin greyish discharge.

But the smell of the cup itself isn’t a diagnostic test for BV.

Silicone products can sometimes retain odours for other reasons, so persistent symptoms or changes in your vaginal discharge are more useful clues than the smell of the product alone.

Can you prevent bacterial vaginosis?

There is no guaranteed way to prevent BV, but you can reduce some known risk factors.

  • Don’t douche or wash inside the vagina.
  • Avoid fragranced intimate washes and other products that irritate you.
  • Condom use may reduce BV risk in some people.
  • If BV keeps returning, ask your doctor whether treating an ongoing partner is appropriate.
  • If recurrent BV occurs while using a copper IUD, discuss whether contraception choice may be contributing.

You don’t need to try to make the vagina sterile or completely odourless.

A healthy vagina naturally contains bacteria and has its own mild scent and normal discharge.

When should you see a doctor?

See your GP or sexual health clinician if:

  • you develop a new strong or fishy vaginal smell
  • your discharge becomes noticeably different from what is normal for you
  • BV symptoms return after treatment
  • you have pelvic or lower abdominal pain
  • you have fever or feel unwell
  • you have bleeding between periods or after sex
  • you have significant itching, burning or vulval irritation
  • you’re pregnant and develop unusual discharge or odour
  • you have a new sexual partner and haven’t recently had STI testing

If significant itching or burning is the main problem rather than odour, read our guide to vaginal thrush, but remember that symptoms alone can’t always identify the cause.

If you’re unsure how to raise vaginal symptoms with your doctor, our guide to talking to a doctor about vaginal concerns can help.

Frequently asked questions

Is bacterial vaginosis an STI?

BV isn’t managed exactly like traditional STIs such as chlamydia or gonorrhoea and routine contact tracing isn’t required. However, current Australian STI guidance recognises that BV-associated bacteria can be sexually transmitted between partners and that partner treatment can reduce recurrence.

Can you get BV without having sex?

Yes. BV can occur in people who aren’t sexually active. Sexual activity is an important risk factor and route for exchange of BV-associated bacteria, but it isn’t the only factor involved.

Does BV always smell fishy?

No. Many people with BV have no symptoms, and not everyone who has symptoms notices a strong smell. A fishy odour together with thin grey or white discharge is a common pattern, but diagnosis shouldn’t be based on smell alone.

Is BV the same as thrush?

No. BV involves a change in vaginal bacteria, while vaginal thrush is caused by an overgrowth of Candida yeast. Thrush more commonly causes itching, burning, soreness and thick or clumpy white discharge, while BV more often causes thin discharge and a fishy smell. They also require different treatments.

Can you have BV and thrush at the same time?

Yes. More than one vaginal condition can be present at the same time. If your symptoms don’t fit neatly with BV or thrush, or treatment for one condition doesn’t resolve them, testing can help clarify what is going on.

Can BV go away on its own?

BV can sometimes resolve, particularly when there are no symptoms. Symptomatic BV is generally treated with antibiotics because treatment relieves symptoms and may reduce associated health risks. If you’re unsure whether treatment is needed, speak with your GP or sexual health clinician.

Why does BV keep coming back after antibiotics?

BV recurrence is common. The vaginal bacterial community may not fully return to its previous state, and BV-associated bacteria can also be exchanged again between sexual partners. Current Australian guidance therefore recommends concurrent treatment of an ongoing partner with a penis.

Should my partner be treated for BV?

If you have an ongoing or regular partner with a penis, current Australian STI Guidelines recommend concurrent partner treatment. If your partner has a vagina, they should be offered testing and treated if BV is found.

Do probiotics prevent BV?

Research into probiotics for BV is ongoing, but current Australian guidance says there isn’t yet enough evidence to routinely recommend vaginal probiotics for treatment or prevention. Specific strains and products may eventually prove useful, but probiotics aren’t interchangeable.

Can menstrual cups cause BV?

Current evidence doesn’t show that menstrual cups increase BV risk when they are used and cleaned appropriately. Recent research has been reassuring, although menstrual products still need to be cleaned and used according to their instructions.

Should I stop using my menstrual cup if I have BV?

You don’t necessarily need to stop using a cup permanently because you’ve had BV. During treatment, follow your healthcare professional’s advice and clean reusable products carefully according to their instructions before using them again.

BV is common and recurrence isn’t a hygiene failure

BV can be frustrating, particularly when it keeps returning.

It isn’t a sign that you’re dirty or that you haven’t cleaned yourself properly. In fact, excessive cleaning and douching can make the vaginal environment less stable.

Our understanding of recurrent BV is also changing. Sexual exchange of BV-associated bacteria appears to play a much bigger role than was once recognised, which is why current Australian treatment now considers ongoing partners as part of the picture.

If BV keeps coming back, you don’t have to simply repeat the same treatment indefinitely without asking why. Talk with your healthcare professional about recurrence, partner treatment and whether another diagnosis, including vaginal thrush, also needs to be considered.

Related reading

Sources and further reading

This article provides general educational information and isn’t a substitute for individual medical advice.