All About Your Vaginal Flora

Beverley Richards DipION Nutritional Therapist

If you have a vagina, you need to read this!

Women are slowly becoming more comfortable talking about their vaginal issues. However, we still have a long way to go when it comes to understanding our vaginas. In this blog, you are about to find out more about your vagina and the bacteria that live there. Plus, how to protect the good vaginal bacteria and how to keep your vagina healthy.

So, what is the vaginal flora?

The vaginal flora, also known as the vaginal microbiome, is the collective term for the colonies of bacteria that live inside the vagina. A healthy, balanced vaginal flora is incredibly important for intimate health. Just like the gut, the vagina is home to billions of bacteria and other microorganisms; some good, some bad, and some ‘neutral’.

The types of bacteria found in the vaginal microflora will vary from woman to woman, but a healthy vaginal microbiome is made up mostly by a genus of bacteria called Lactobacillus. In fact, it is estimated that at least 95% of the normal vaginal flora should be made up from the Lactobacillus genera of bacteria. The following species from the Lactobacillus genus are all present in the vagina: Lactobacillus reuteri, Lactobacillus rhamnosus, Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus iners and Lactobacillus jensenii. However, not all the strains within each of these species of bacteria will be resident in the vagina. Some strains may prefer to live in the gut. Bacteria are classified according to their genus, species, and strain. Strains within each species may have very different properties, and therefore ‘live’ or colonise different areas of the body. Read more about the importance of strains in this article: Are all strains of bacteria the same?

For example, we know that some strains of Lactobacillus reuteri and Lactobacillus rhamnosus prefer to live in the gut, whereas the Lactobacillus rhamnosus GR-1® and Lactobacillus reuteri RC-14® strains prefer to live in the vagina. These, and the other strains of probiotic bacteria in the vaginal flora, work very hard to protect you against vaginal infection.

The importance of the vaginal microbiome

Having mentioned that the vaginal flora, or more specifically the ‘friendly or ‘good’ vaginal bacteria help to prevent vaginal infection, let’s take a look at how they actually do that.  

Lactobacilli are called Lactobacilli because they produce lactic acid. This function is what keeps our vagina's pH balance at a slightly acidic level and prevents the growth of yeast, bad bacteria and other pathogenic organisms which prefer a more alkaline environment, to survive. Fun fact: The pH balance of a healthy vagina is around 4.5 which is the same as wine, tomatoes and beer!

In addition to lactic acid Lactobacilli also produce hydrogen peroxide and other substances which inhibit the growth of unfavourable or ‘pathogenic’ strains of bacteria and yeast. Anything that upsets the delicate balance of the vaginal microbiome gives pathogens a chance to overgrow and cause intimate health infection.

Bad bacteria can grow in the vaginal flora for many reasons. Sexual intercourse, high-sugar diets, the use of perfumed body wash products, antibiotics and even stress are known as potential triggers! An overgrowth of bad or ‘unfriendly’ microbes in the vagina can lead to:

Vaginal flora infographic | Probiotics Learning Lab
What the vaginal flora does and how we can make sure it's looked after!

Women’s vaginal health – the different life stages

Your vagina contains more bacteria than anywhere else in your body, after the bowel. Everyone’s vaginal microbiome is different. As we progress through our life stages from birth to puberty, our reproductive years and possible pregnancy, and menopause and beyond, hormonal shifts occur. Each of these hormonal shifts presents certain challenges to the vaginal microbiome, which can disrupt the harmonious balance of good and bad bacteria in the vagina.

Birth & Girlhood

At birth, our vaginas are sterile. Shortly after or during birth, the baby's vaginal microbiome starts to populate when they take on bacteria from their mother, typically from the Bifidobacteria genus. During early childhood, the vaginal pH is neutral or only slightly alkaline. From this point up until girlhood, there is a decrease in populations of Lactobacillus and pre-pubescent girls, have lower populations of Lactobacillus species in proportion to the other species.

Top tip for parents: Vaginal infections can arise in pre-pubescent girls, often due to highly scented bath products. Encourage your young daughters to wipe themselves from front to back when going to the loo. Also don’t use perfumed soaps, especially directly into the vaginal area.


The teenage years are a challenging time for young girls with their bodies changing as they enter puberty. Girls can find these changes difficult and embarrassing. There are also big changes in the vaginal microbiome at this time. Ever-increasing levels of oestrogen result in high levels of glycogen to be present in the vaginal lining. The Lactobacillus family of bacteria ferment glycogen resulting in the production of lactic acid. This helps to protect the vagina at this challenging time.

If the vaginal microbiome is left unprotected however, a pubescent girl's vaginal pH levels exceed 4.5 and become the ideal breeding ground for infections such as bacterial vaginosis (BV). BV is the most common vaginal infection in women ages 15-44, with one in three women thought to suffer from it at some time in their lives.

Not just for bearing the fruits of your loins, a healthy vaginal flora is super important for fighting off infections and bad bacteria

The reproductive years and pregnancy

Once we have transitioned through puberty a woman reaches her reproductive years. Sexual activity may follow and with it and the chance of pregnancy. During pregnancy, the vaginal flora shifts and becomes even more dominant in Lactobacilli. It is thought that this increased dominance of Lactobacilli is to safeguard against infection which can be triggered at this vulnerable time, due to the hormonal shifts. Read more about: Pregnancy and the vaginal microflora.

Women may also find that they are more prone to vaginal infections just before or around the time of their monthly period. Again this is triggered by hormonal shifts at this time.

Menopause and beyond

The cessation of monthly periods is only one change that occurs at menopause. Due to a drop in sex hormones, especially oestrogen women may start to suffer from vaginal dryness or atrophy. A reduction in vaginal glycogen leads to a reduction in protective Lactobacilli, so post-menopausal women are at increased risk of vaginal infections and UTI’s, such as cystitis.

Triggers for vaginal imbalance and infections

Let’s take a more in-depth look at the triggers for vaginal infections and disruption to the good vaginal bacteria. (Some have been briefly touched on when discussing the various life stages).


Our periods can be a monthly challenge for the vagina. The hormonal fluctuations and onset of the menstrual cycle can disrupt the balance of the vaginal flora, sometimes acting as a trigger for infections like BV. It is common for the vaginal microbiome to be disrupted during the first week of the menstrual cycle. However, it’s not clear whether this is due to the menstrual flow itself or hormonal changes1.

Bacteria levels change during menstrual flow; pH rises and Lactobacillus bacteria decrease. At the same time, there is an increase in numbers of other bacteria normally present in the vaginal microbiome too. When our menstrual flow stops, pH decreases again and the numbers of Lactobacilli increase. This reinstates the usual balance and is consistent from cycle to cycle.


Any sexual activity, particularly unprotected sex with a partner, can introduce new micro-organisms into the vagina.

This exposure can result in an immune response against the bacteria, causing inflammation2. When the Lactobacillus population of bacteria is disrupted, these less desirable bacteria take over and leave us vulnerable to infections.

The use of sexual lubricants during sex can also be problematic for the vaginal flora. Some ingredients used in these products may increase the likelihood of intimate health infections. Particular ‘nasties’ to look out for (and avoid) include any flavourings or scents (as these often contain sugar which promotes yeast infections, such as thrush), glycerine and glycerol (as both can damage and dehydrate the vaginal epithelia).

Some lubricants also contain spermicides, to immobilise sperm and prevent pregnancy, however these ingredients may also increase the likelihood of vaginal infections. One particular spermicide, Nonoxynol-9 (N-9) has been proven in clinical trials3 to damage vaginal tissue and increase the transmission of STIs, including HIV.

Try to use as natural a lubricant as you can and check the pH value of the product. Products should have a similar pH to the vagina itself, of around 3.8-4.5. There are plenty of good natural options on the market now.

However, having plenty of good bacteria in the vaginal flora can help create a healthy defence against sexually transmitted infections4, such as chlamydia.


Good hygiene is key for intimate health. However, women often feel the need to wash their intimate area using highly perfumed bath and shower products. Harsh soaps can disrupt our balance of vaginal flora. In fact, the vagina is designed to keep itself clean with the help of natural secretions (discharge), so women’s vaginal health doesn’t require the use of strong products. Hot water and some optional unscented soap are recommended for cleaning your vagina effectively.

How to know you're doing it right? A healthy vagina should not smell offensive but may have a natural odour.


During pregnancy, there is a significant decrease in overall microbial diversity, but there's a marked enrichment of the Lactobacillus species5. This is thought to possibly help protect against infections during pregnancy.

Our vaginal flora increases massively with amounts of Bifidobacterium, too. Both Lactobacillus and Bifidobacterium crowd out other bacteria species preventing harmful bacteria from going up into the womb where they could infect the amniotic fluid, placenta and baby.

During birth, the first bacteria to arrive in the baby’s gut come from our vaginal microbiome helping to protect against harmful bacteria taking hold. This sets up our babies' own microbiomes.

Read more about this fascinating topic: Do babies come in to contact with bacteria in the womb?


You may not realise it, but stress can also disrupt the microbiome, both in the gut and the vagina6. The "fight-or-flight" response that we experience when under stress may be harmful to the vaginal flora, especially if the stress persists on a long-term basis.

Here's the science bit: Prolonged exposure to stressful situations can stimulate the production of cortisol, which will affect levels of glycogen in the vagina, and consequently populations of Lactobacilli which like to ferment it. A reduction in levels of Lactobacilli can increase the risk of vaginal infections.

Healthcare professionals may wish to read more about stress in our blog: Could live cultures help with stress and anxiety?


Antibiotics are often used to treat vaginal infections. Unfortunately, this medication can kill off good as well as bad bacteria. This leaves you even more vulnerable to future infections once the course of treatment is over.

It can be helpful to take probiotics during and after a course of medication. This helps to protect the body’s precious good bacteria. Antibiotics can allow bad bacteria to overgrow in the gut, and these pathogens may travel to the vaginal flora and cause infections.

It's a common suggestion to take probiotics if you're someone that suffers from persistent vaginal infections and who has had lots of antibiotics. Look for strains which have been tested alongside antibiotics when choosing which probiotics to take.


When a woman’s reproductive phase is over, she approaches and goes through menopause. This changes the vaginal microbiome once again.

The vagina is particularly vulnerable to infection at this time, as decreased oestrogen and therefore less glycogen results in fewer populations of Lactobacilli (the good bacteria). With less lactic acid being produced, the vaginal pH increases. Such changes in the vaginal microbiome may result in vaginal dryness, lowered sexual health and various other symptoms.

Some women find it helpful to take a women’s vaginal probiotic at this time, to help keep the vaginal microbiome healthy and well supported.

Woman holding tummy
So what can women do to take care of their vaginal flora?


How to keep your vagina healthy and happy

  • Use hot water/plain, unperfumed soaps to wash the area around the vagina (the vulva) gently every day.
  • Avoid vaginal douches as they can be very disruptive to the normal vaginal flora.
  • Don’t use scented feminine products or perfumed toilet paper.
  • Take a probiotic daily. It is recommended to look for a specific women’s vaginal probiotic, which contains strains of bacteria that like to live in the vagina and are proven to reach the vagina alive.
  • Practice safe sex and use protection. Urinate immediately afterwards and wash the vagina gently with water and unperfumed soap as soon as possible.
  • Avoid chemical additives and spermicides in sexual lubricants and condoms. Choose natural versions that are aligned to the vaginal pH and non-irritant to the delicate vaginal epithelia
  • Avoid tight clothing and synthetic fabrics against your skin.
  • Enjoy a varied diet of fresh foods, including fresh fruit and vegetables, but keep an eye on your sugar intake, as this will feed the wrong type of bacteria in your body.
  • Support your immune system. Over 70% is based in your gut so that's a good place to start!
  • Finally, talk about your vagina! If you have any worries and concerns, share them, and seek medical advice if necessary. Understand its complexities and remember how amazing vaginas are throughout our lives.

Healthcare practitioners may wish to find out more about the Lactobacillus genus on our Probiotics Database, over at the Probiotic Professionals pages.

If you enjoyed this article, you might be interested in the following:

Which probiotics are best for women?

Does pregnancy change the vaginal microflora?


  1. Morison L, Ekpo G, West B, et al Bacterial vaginosis in relation to menstrual cycle, menstrual protection method, and sexual intercourse in rural Gambian women Sexually Transmitted Infections 2005;81:242-247.
  2. Lenka A. Vodstrcil et al (2017) ‘The influence of sexual activity on the vaginal microbiota and Gardnerella vaginalis clade diversity in young women’, PLOS ONE,
  3. Van Damme, L., et al., Effectiveness of COL-1492, a nonoxynol-9 vaginal gel, on HIV-1 transmission in female sex workers: a randomised controlled trial, Lancet, September 2002, vol 360, no. 9338, pp 971-97
  4. Molenaar, M. C., Singer, M. & Ouburg, S., 2018. The two-sided role of the vaginal microbiome in Chlamydia trachomatis and Mycoplasma genitalium pathogenesis. Journal of reproductive immunology, Volume 130, pp. 11-17
  5. Aagaard, K., Riehle, K., Ma, J., Segata, N., Mistretta, T. A., Coarfa, C., et al. (2012). A metagenomic approach to characterization of the vaginal microbiome signature in pregnancy. PLoS ONE 7:e36466. doi: 10.1371/journal.pone.0036466Amabebe,
  6. Emmanuel and Dilly O C Anumba. “Psychosocial Stress, Cortisol Levels, and Maintenance of Vaginal Health” Frontiers in endocrinology vol. 9 568. 24 Sep. 2018, doi:10.3389/fendo.2018.00568