When Sophie first started noticing the symptoms of bacterial vaginosis, she thought she had an STI. “I think I was about 25,” the 29-year-old tells me. “I felt gross, knew something was wrong from the [fishy] smell and a friend had once told me she got chlamydia and it smelt, so I was assuming it was that.

“I was away travelling with work and knew I wouldn’t be able to get it checked ‘til I got home, so I was super self-conscious,” Sophie continues. “I went straight to a sexual health clinic when I got home and got tested. [The results] came back all clear but they said I did have [bacterial vaginosis].”

The words ‘fishy odour’ and ‘vagina’ don’t come together in a sentence anyone wants to hear; unless there’s a negative in there.

But as undesirable as a fishy vaginal smell may be, it happens. Getting a waft of fishy air whenever you uncross your legs and hoping it’s just down to sweaty inner thighs; googling ‘why does my vagina smell fishy’ at 2:00am while your partner snores beside you: none of this is pleasant, but plenty of people with vaginas have been there – and there’s one very likely culprit.

“The classic cause of a fishy odour [in the vagina] is an overgrowth of a group of bacteria called anaerobic bacteria, resulting in a condition called bacterial vaginosis, or BV,” says Mr John Butler, Consultant Gynaecologist and Medical Director at the Lady Garden Foundation. “This is very common, affecting 25% or more women globally.”

“[BV] can cause vaginal irritation, a fishy odour down below and sometimes itching,”

says Mr Narendra Pisal – Consultant Gynaecologist at London Gynaecology. “It may [also] cause burning pain during intercourse. Making a diagnosis isn’t always straightforward and a visit to the GP may be needed.”

Butler adds that many women don’t experience any symptoms of bacterial vaginosis at all, but concurs with Pisal that the classic symptoms include a “foul-smelling ‘fishy’ vaginal odour [and] vaginal itching,” together with “burning during urination.”

Butler also outlines a “thin, grey, white or green vaginal discharge” as being among the other common symptoms of bacterial vaginosis – something Sophie noticed once she got her diagnosis.

“I got [BV] every two-four months for about [a year and a half] until I got my coil removed,” she says. “[These times] I recognised the symptoms[:] the [fishy] smell and the watery discharge. [The] symptoms were generally the same each time; I just hated that it kept coming back.”

Sophie was given antibiotics by her GP: “Which worked each time I got it, but didn’t stop it coming back again,” she warns. Antibiotics are a key method of treatment: Pisal says these can be either “vaginal or oral”, and Butler lists metronidazole as an example. Other treatments include oral probiotics, which Pisal says “may help to restore the balance of the bacterial environment in the vagina.”

If, at this point, you’re starting to panic that everyone you know is backing away from your fishy vaginal smell: it’s time to take a breath, because Butler has some reassuring words that will, hopefully, banish any shame or embarrassment surrounding fishy vaginal smells. “The vagina is host to millions of bacteria and sometimes an imbalance of these can result in malodour in underwear, wipes or in any discharge,” he says. “It’s very rare for anyone else to be able to notice this.” So you can relax: you most likely haven’t been sending your colleagues running for the hills every time you get up from your desk.

Plus, Dr Ayanthi Gunasekera is a Specialist Registrar in gynaecology at London Gynaecology: and she added that another cause of a fishy vaginal smell could be trichomoniasis rather than BV. It’s an STI triggered by a parasite, and which Gunasekera describes as including symptoms such as, “green yellow” discharge and as needing a course of antibiotics as treatment.

So, with this in mind, it’s always worth going to see a GP or gynaecologist – even if you’re fairly sure BV is the cause of your symptoms.

“When you see a doctor, a gynaecological examination including [a] speculum inspection of the cervix and vagina will be recommended,” says Pisal. “Swabs may be taken to exclude common causes; [and] a smear or sexual health check will also be recommended, depending on your history. If the diagnosis is obvious, your doctor may offer you treatment during the same visit or may contact you once the results are back.”

There’s no denying that BV is highly likely to be the reason for a fishy vaginal smell: and so it’s worth thinking about how best to prevent it. And the best possible deterrent? Let your vagina be.

“The vagina is self-cleansing,” Gunasekera explains. “It is important to have good hygiene practices, but this should not include vaginal douching or using perfumed products to cleanse the vagina as these products can disturb the [vagina’s] natural bacterial flora.

Use only water to wash, dry well, wear cotton underwear and let your vagina ‘breathe’ by avoiding wearing tight clothing all the time.”

Butler agrees: he points out that a useful deterrent to bacterial vaginosis is to “[avoid] using soaps or irritants to the vagina and vulva”, together with using condoms.

And the answer to another possible deterrent lies in Daye’s upcoming Vaginal Microbiome Screening (VMS): an opportunity to avoid sharp, poky swabs by simply returning a used (yes, used) Daye tampon back to the Daye lab. This will then be analysed for imbalances in vaginal microbiome; imbalances that can lead to conditions like BV. So, you’d be significantly reducing your chances of contracting BV in the first place; and who can argue with that?

If you do have an imbalanced vaginal microbiome, you’ll hear via an online result (nice and discreet), and you’ll get a range of aftercare options to choose from, too. If you want more details (and why wouldn’t you?), have a read here; and be sure to provide your email if you’d like to be one of the first to try the program.

And in the meantime, see a healthcare professional for any fishy (or other) vaginal odours.

As Butler says: “Doctors, nurses, pharmacists and sexual health clinics are here to help you, so please don’t be afraid to talk to us. Vaginal discharge is healthy and normal; but if it’s different or has a bad smell then please come and get checked, as most of the causes can be easily treated or prevented.”