What happens if bacterial vaginosis is left untreated?

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Reviewed by Dr Fran Yarlett on June 1, 2023

What happens if bacterial vaginosis is left untreated? | The Lowdown
Will bacterial vaginosis go away on its own and what happens if it is left untreated? We asked a doctor for the lowdown...

What’s the lowdown?

  • Bacterial vaginosis is a very common condition that is caused by an imbalance in bacteria within your vagina 
  • You often won’t know if you have bacterial vaginosis as many women never have symptoms but the most common symptom is a fishy/strange smelling, watery discharge 
  • There are many risk factors that can predispose you to bacteria vaginosis including the use of intimate hygiene products, being sexually active, multiple sexual partners, having an IUD and smoking 
  • Whilst bacterial vaginosis is usually harmless it can cause complications in pregnancy 
  • Bacterial vaginosis can usually be kept at bay by managing risk factors and triggers. If treatment is needed it is easily treatable with antibiotics.

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As with most things in life, your vagina likes to be in balance. One move too far up the pH scale or a change in hormonal balance and things can get messy. The balance of bacteria in your vagina, known as the microbiome, is no exception.Your vagina hosts more than 500 types of bacteria alone which help your vagina function as it should. 

The most common bacteria is Lactobacilli which, acting as a security guard of sorts, keeps the other bugs that call your vagina home in check. A few things can catch this security guard off duty causing all hell to break loose – cue smelly discharge and sadness. 

Sometimes, this balance of bacteria is altered which can lead to a condition called bacterial vaginosis (BV), something up to 50% of women in the UK struggle with and is the most common cause of abnormal discharge in people who menstruate. Despite years of study and speculation on the cause of bacterial vaginosis, no direct cause has been found. Ugh. However, we do know that a few things increase your chances of getting BV and can trigger a recurrence…

What can cause bacterial vaginosis?

Vaginal pH

Your vagina should naturally have an acidic pH, but there are some factors that can throw this off balance, increasing your risk of infection.  Vaginal douching, the use of intimate ‘hygiene’ products, having an IUD (both copper and hormonal), your period, and semen can all be responsible for a climb up the pH ladder. 

During menstruation, as if bleeding for 3 to 7 days wasn’t enough already, your vaginal pH naturally rises opening the door to potential BV. The jury is still out as to exactly why the coil may be linked to BV but theories include changes to bleeding patterns and irregular periods due to the hormonal coil (IUS) or copper coil (IUD) causing  pH swings. True to the concept of opposites attracting, semen is alkaline and therefore increases your vaginal pH which can trigger BV. This is one of the reasons why being sexually active is considered to increase your BV risk, and symptoms of BV like a strong fishy smell occur after sex. Although BV is not itself an STI.

Recent antibiotic therapy

Modern medicine is a wonder, but we still haven’t quite figured out how to kill off the nasty bacteria, wherever it may be in your body, whilst leaving all of the good ones alone. Taking oral antibiotics may kill off too many of the vaginal Lactobacilli that are holding down the fort, and lead to conditions like thrush as well as bacterial vaginosis. 


Studies have shown that BV affects around up to 55% of black women compared to up to 15% of caucasian women. Women are often underrepresented in medical research, black and ethnic minority women even more so, so there is still research to be done as to why conditions like thrush and BV disproportionately affect them. One possible reason could be that black women have a more diverse vaginal microbiome, whereas white women have a more Lactobacillus-dominated microbiome – i.e. the bacteria that keeps your pH balance in check.



The effect of smoking on the balance of bacteria in the vagina is two fold. Firstly, it encourages the production of the BV causing bacteria and its by-products, which produce the fishy smell, and secondly, smoking prevents the vaginal tissue from responding to oestrogen, which helps to maintain strong, healthy vaginal tissue. Evidence shows that smoking weakens your immune system making it harder to prevent and clear high-risk HPV infections that could lead to cervical cancer. Smoking also has other significant detrimental effects on your overall health too, so it’s 10/10 recommended to kick the habit.

Same sex partners

Lesbians, listen up! You and your partner may have similar vaginal lactobacilli which can decrease your protective measures and increase your chances of getting BV. 

Oral sex

Although oral sex is an essential part of a healthy sex life for many of us, exposing your vaginal bacteria to someone’s mouth bacteria can confuse all bacteria involved and lead to BV. 

Does the coil cause bacterial vaginosis?

Using the copper coil may be associated with a higher risk of bacterial vaginosis of up to 28% compared to not using any contraception. Unfortunately, studies haven’t looked into the hormonal coil in as much detail. It seems that when a coil is removed, the risk of BV goes back down to baseline.

How do I know if I have bacterial vaginosis?

BV can be, and often is, asymptomatic, meaning you won’t have any symptoms, and may resolve on its own in a lot of cases. It is also usually harmless and many of us won’t know or realise we’ve had recurring bouts of BV throughout our lives. However, the hallmark symptoms of bacterial vaginosis are watery discharge (often clear or grey) and a fishy or unpleasant smell. 

Diagnosis is usually made by your doctor or nurse, but there are some tests they can do when examining you, including testing your vaginal pH (using a small paper test strip), that can assist with diagnosing BV. If you’re someone who has had BV in the past you may recognise the characteristic symptoms when they recur.

Will bacterial vaginosis go away on its own?

Yes bacterial vaginosis can go away on its own and you probably won’t even know it is happening. 50% of women who have bacterial vaginosis may be asymptomatic and under current guidelines, screening people who don’t have symptoms for BV is not recommended. Some people are aware of their risk factors or triggers and are able to manage these to help reduce recurrences of BV. 

How long does it take for bacterial vaginosis to clear up? 

BV can clear up on its own but it is difficult to say how long this might take, as every vagina is different and the circumstances which trigger BV will differ between people. If you’re experiencing a BV flare up during your period, symptoms usually resolve within a few days of your finishing your bleed as the pH normalises on its own. If you require treatment however, symptoms usually resolve within 5 to 7 days.

Treatment for BV is currently only recommended for those experiencing symptoms, as studies have shown that there’s generally no benefit in treatment for those without, compared to allowing the bacterial vaginosis to go away on its own. 

What can happen if bacterial vaginosis is left untreated?

Bacterial vaginosis is not usually something you need to worry about; a huge number of us won’t even know we have it and it generally won’t cause any harm. Some of the risk factors for BV may be troublesome, though. Unfortunately, like that ex who just WON’T go away, recurrence is a problem and so far there’s no telling why this happens. Not being properly diagnosed, having a sexually transmitted infection (STI) at the same time, or ineffective treatment to start with are among some of the culprits, as well as not addressing ongoing risk factors. This study also suggests that rates of recurring BV are as high as 80% three months after effective treatment.

STIs in particular need to be addressed as they can be spread and lead to further complications, so make sure you know the STI symptoms to look out for. The good news is that condom use is effective in keeping both away! A little reminder: condoms are the only form of contraception to protect you against STIs.

BV can increase the risk of STIs

Chlamydia and gonorrhoea are among the STIs described to be associated with BV. A high level of anaerobic organisms (bugs that don’t require oxygen to function) can cause damage to the vaginal wall which can increase the risk of getting infections. There is also interesting research to suggest that your main groups of normal vaginal bacteria may be protective against certain infections such as HPV. So keeping your vaginal bacteria in tip-top shape is well worth the effort. 

Complications during pregnancy

Premature labour, miscarriage and womb infections are linked to having BV during pregnancy. Often though, as with those of us who aren’t carrying a baby, pregnant women don’t have any symptoms and the majority don’t have any problems. Currently in the UK you will only be tested for BV in pregnancy if you have symptoms. There is also currently no evidence to support treating BV in women who are pregnant who do not have symptoms but your doctor would discuss this with you.

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Pelvic inflammatory disease (PID)

Commonly caused by STIs like chlamydia and gonorrhoea, pelvic inflammatory disease (PID) can also be caused by bacteria naturally occuring in the vagina, however there is no specific link to BV. Research shows that while some bugs cross over the two conditions, a direct relationship has not been found. 

What is the best way to treat bacterial vaginosis?

Your body is pretty smart and your vaginal microbiome is usually restored all on its own. Managing risk factors and figuring out your triggers often does the trick.

Other options include lactic acid gels, such as Relactagel, which encourages your normal vaginal bacteria and restores your normal pH. This can be used to prevent BV as well as treat it if you’re prone to recurrences. 

Traditional treatment consists of simple antibiotic therapy. Either administered in tablets to swallow or a gel or pessary to place in the vagina. The most commonly used are metronidazole and clindamycin. 

These antibiotics are usually prescribed for 5 to 7 days, however if symptoms recur then treatment may be as long as six months. One off, high dose treatment with metronidazole can also be offered to non-pregnant women. 

Keep in mind that if you have a same sex partner, they may also need to be treated. 

What to do if your bacterial vaginosis doesn’t clear after treatment

If your symptoms haven’t gone away after treatment it’s best to speak to your GP or sexual health clinic to make sure that nothing else is going on. You should consider whether you need an STI test as these can have similar symptoms to BV. Other conditions such as thrush may also be mistaken for BV. Your doctor or nurse can also help you identify risk factors or triggers.  We also have wonderful women’s health doctors at the Lowdown who can run through your symptoms with you to figure out what might be going on.

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Dr Brenna Weaver MBChB (WITS) is a South African trained doctor, who became passionate about women’s health whilst working in under-resourced, rural communities, doing everything from Caesarean sections to contraceptive drives.