Understanding Vaginal Odours: What's Normal?

Vaginas have their own unique scent, and shouldn’t smell like your soap, perfume, fruit or flowers. There isn’t much research on vaginal odours, despite it being one of the most common reasons for a doctor’s visit.

You’re likely already familiar with what your vagina’s normal scent is, although this can vary slightly with changes in your menstrual cycle.

However, there are occasions when things might smell a bit off or downright gross. You’re not alone if you’ve found yourself asking the internet questions like, Why does my vagina smell like onion? or even why does my vagina smell like death?.

Here, we delve into vaginal odours, from the fresh to the foul, and explain the various vaginal infections, environmental factors, and hormonal fluctuations they’re associated with. These include:

How to accurately check vaginal odour – the sniff test

Now, this is the home-grown My Vagina version, not to be confused with the Whiff Test! But, it’s generally effective at evaluating your own vaginal odour if you can reach your vagina, and have a normal sense of smell.

The sniff test is best done after a shower, to avoid picking up regular odours from your groin or vulva, but can be done anytime you are relatively clean.

First, wash your hands in warm water, but don’t use any scented soap – you want your hands to be completely smell-free. Any fragrances in soap, perfume or moisturiser will interfere with your nose doing this vaginal odour detecting job.

Gently spread your labia and insert one finger – whichever is easiest – into your vagina, give it a wiggle to ensure it’s coated in your vaginal fluids, and then sniff your finger.

Easy! The sniff test can be done anytime you need a clear reading on what your vaginal fluids smell like. You can use the sniff test on your vulva, in the crevices, to see what’s normal there also.

Check after a shower, then at the end of your day, and see the differences!

Where does vaginal odour come from?

The origin of vaginal odour is complex and likely varies from person to person. When it comes to vaginal odours, several factors are in play.

In simple terms, vaginal odour is a combination of scents produced by the byproducts of different microbes within the vaginal microbiome and their interactions with your vaginal secretions.

If you’re interested in which bacteria and fungi are in your vagina, get a comprehensive vaginal microbiome test (order online, anywhere in the world).

In fact, all body odour originates from the different smells bacteria produce, known as bacterial odorants.

Certain vaginal bacteria release smelly chemicals, specifically ones called “biogenic amines.” These biogenic amines can raise the vaginal pH.

Currently, Dialister, Prevotella, Parvimonas, Megasphaera, Peptostreptococcus, and Veillonella are suspected of being responsible for producing most of the pungent molecules because they possess the necessary genes to produce biogenic amines.

Certain biogenic amines (putrescine, cadaverine) are produced by the microbes that cause BV and have a smell resembling rotting meat or fish – hence the fishy odour associated with BV!

However, biogenic amines aren’t the sole cause of vaginal odour. Odour occurs when vaginal bacteria mix with other fluids or bacteria nearby.

Factor in discharge, the microbes in genital sweat, menstrual blood, a dash of urine, and occasionally trace amounts of faeces, and you’ve got a comprehensive picture of what makes up vaginal odour.

For example, the microbes in digestive gas produce hydrogen sulphide, a bacterial odorant that smells a bit sulphurous, like rotten egg. Vaginally, this odour is associated with certain bacteria and conditions.

Types of vaginal odours and what they can mean

Earthy, ripe, or musky vaginal odour

Although there’s no single smell for a healthy vagina, vaginal odour may be described as a bit musty, pungent or ‘of the sea’.

A stronger version of your vagina’s usual odour is typically not a problem. The types of bacteria and their numbers fluctuate with hormones across the menstrual cycle, which can alter vaginal odour and pH.

At the end of menstrual bleeding or after being sweaty or having a long day, odour might be a little stronger.

BO vaginal odour

The vulva contains two types of sweat glands, eccrine and apocrine. Eccrine glands produce odourless moisture; apocrine glands produce oily secretions that interact with skin bacteria to create smells.

Apocrine glands are found largely on hair-bearing skin, including the pubic area. Thus, you sweat, the crotch area can smell like BO. By the end of the day, the vulva won’t be as fresh.

Onion-like vaginal odour

If you have a distinctly oniony vaginal or groin odour, you may be dealing with a metabolic issue with sulphur, which may benefit from the careful eye of an experienced practitioner. Your vaginal microbiome may be looking great, and you may have no other symptoms.

If this is you, we strongly recommend you book in with one of My Vagina’s qualified, experienced vulvovaginal specialist practitioners. You may not have a vagina problem, but an issue processing sulphur compounds from food and regular body metabolism, and it’s appearing as oniony odour.

Rotten vaginal odour (or similar to eggs)

Let’s be honest; many of us have been here. While unpleasant, vaginal odour isn’t a cause for embarrassment, and we know it doesn’t reflect your personal hygiene habits. But, it is a sign something may be amiss, so let’s explore.

Aerobic vaginitis (AV)

Aerobic vaginitis is strongly associated with foul, pungent vaginal odour. Similar to BV, aerobic vaginitis is associated with a decrease in Lactobacillus dominance in the vaginal microbiome and sometimes an elevated pH (over 4.5).

Interestingly, some AV-causing bacteria are lactic-acid bacteria (LAB), so the pH may be normal in a premenopause. Postmenopause, the pH can be very variable.

AV is the overgrowth of certain types of gut bacteria, typically E. coli, Staphylococcus aureus, group B Streptococcus (GBS), and Enterococcus faecalis, which enjoy greater access to oxygen to multiply, hence the name.

A lost tampon

A lost or forgotten tampon can also produce a rotting smell. This odour becomes stronger the longer the tampon remains in the vagina, as bacteria that thrive in a blood-rich environment multiply.

Leaving a tampon in the vagina for over 6-8 hours comes with an increased risk of toxic shock syndrome (TSS) – a rare but dangerous condition where bacteria spread throughout the body, releasing harmful toxins. The quality of your menstrual products makes no difference.

Some experts and research suggest that changing tampons too often may introduce excessive oxygen into the vagina, mainly because oxygen is required for TSS toxin production.

Therefore, when using tampons, follow guidelines and menstrual flow, using the lowest absorbency tampon for your flow.

Menstruation

A milder odour can occur during bleeding. Make sure to change pads, tampons, cups or other menstrual products around every 4-6 hours.

Fishy, meaty, or cheesy vaginal odour

The vaginal odour can resemble scents from a farm or the sea. It’s completely normal for certain microbes to emit scents reminiscent of fish, meat, or cheese – all food has bacteria in it too.

Bacterial vaginosis

The microbe most commonly associated with BV – G. vaginalis – produces specific chemicals that create a strong fishy or even putrid fish-like odour. These chemicals include trimethylamine (TMA), putrescine, and cadaverine.

A study from 2002 examining TMA levels in vaginal fluids of women with BV found TMA in all those that had high vaginal bacterial diversity (Nugent score 7-10). TMA was either absent or present in small amounts in those with Lactobacillus-dominant microbiomes (Nugent scores 0-3).

Trichomoniasis

A fishy odour can be caused by trichomoniasis, an STI caused by a parasite called Trichomonas vaginalis.

The digestive system and urogenital tract

Fishy vaginal odour can also be associated with non-bacterial conditions like urinary incontinence, malignant ulcers, trimethylaminuria, or chronic constipation.

Several studies have found that some types of gut bacteria increase the production of trimethylamine (TMA), the fishy odour chemical. These bacteria include Anaerococcus, Providencia, Edwardsiella, Clostridium, Collinsella, Desulfovibrio, Lactobacillus, and Proteus.

Semen, sex, and inflammation

Since the pH of semen is naturally higher than the ideal vaginal pH, it can temporarily alter the vaginal pH. This can result in a fishy, meaty, or cheesy odour.

A sulphur-like, chickeny odour is also linked to the interaction between sweat and skin bacteria. This may be more noticeable after sex when you’ve become hot and sweaty.

Bleach or ammonia vaginal odour

A sign of bacterial vaginosis

Although bacterial vaginosis typically presents with an unpleasant, fishy odour, sometimes an ammonia-like vaginal odour can be associated with BV, particularly in cases caused by an overgrowth of Prevotella bivia.

A study from 1997 found that when P. bivia was cultured with certain nutrients, it produced high levels of ammonia, which then promoted the growth of G. vaginalis.

Discharge and sweat

Discharge or sweat and small amounts of urine can give vaginal odour an ammonia or urine-like quality. Those with urinary incontinence may find this to be more of a problem, with small urine leaks throughout the day.

Sour, tangy, vinegar, sour, yogurt, bread vaginal odour

When vaginal odour is more sourdough than regular yeasty bread, it might be a good sign – sour, tangy vaginal odour can mean lots of protective lactobacilli. But, regular bread smell might mean a yeast infection.

A healthy vagina’s acidic environment (where Lactobacillus thrives, reducing harmful microbes) maintains a pH between 3.8 and 4.5, producing this pickled or fermented odour.

Metallic vaginal odour

Period blood

Metallic vaginal odour is associated with menstrual blood, which has a high iron concentration. This is normal.

Light bleeding after sex can also amplify this metallic, tinny scent. Unexplained mid-cycle bleeding or spotting might also take on this vaginal odour.

If bleeding or spotting is due to an infection, such as an STI or pelvic inflammatory disease (PID), consult a doctor.

Fruity, sweet, bittersweet, molasses

Crotch sweat

At times, crotch sweat interacts with skin bacteria to produce fruit or grapefruit odour. Some microbes within a healthy vaginal microbiome can also emit molasses-like, earthy odours.

What we don’t know about vaginal odour

There’s a significant lack of research regarding the various vaginal odours and their causes.

Apart from fishy odours, and when offensive and misogynistic narratives suggesting that these odours are linked to a woman’s hygiene and worth, there isn’t a great deal of research into vaginal odours.

It’s important to get to know what’s normal for you.

Minor changes in vaginal odour are normal and expected. However, anything that smells unpleasant, fishy, or foul needs a doctor.

Above all, become acquainted with your distinctive vaginal odour and how it changes throughout your menstrual cycle. You’ll instinctively know when something isn’t right, and when in doubt, refer back to this guide, consult your doctor, and get a comprehensive vaginal microbiome test.