All About Your Vaginal Flora

Beverley Richards DipION Nutritional Therapist

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

Women are becoming more comfortable talking about their vaginal issues. However, we still have a long way to go when it comes to understanding our vaginas. You are about to find out more about your vagina, the bacteria in your vagina, and how to keep it happy with our health checklist (scroll to the end for that!)

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 benign.

The types of bacteria found in the vaginal microflora will vary from woman to woman, but the vaginal microbiome is made up mostly by a genus of bacteria called Lactobacillus. A healthy vaginal flora typically contains the following species from the Lactobacillus genera: Lactobacillus reuteri, Lactobacillus rhamnosus, Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus iners and Lactobacillus jensenii. However, not all of the strains within each of these species of bacteria will prefer to live in the vagina rather than the gut. Bacteria are classified according to their genus, species and strain. Strains within each species may have very different properties. 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. 

How do they do that? Well, here’s the science bit. Lactobacilli are so-called because they produce lactic acid, along with hydrogen peroxide and other substances. 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!

Bad bacteria can grow in the vaginal flora for many reasons: sexual intercourse, high-sugar diets, antibiotics and even stress are known as potential triggers! This bad bacteria growth can lead to:

Vaginal flora infographic | Probiotics Learning Lab

What the vaginal flora does and how we can make sure it's looked after!

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 pregnancy, menopause and beyond, hormonal shifts occur and our vaginal flora faces certain challenges 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, 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 with 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

Once into adulthood, we reach our reproductive years, potential pregnancy, menopause and more. With this comes a myriad of different factors which can disrupt the harmony in the vaginal microbiome, resulting in possible infection and other health problems.

Triggers for vaginal imbalance and infections


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.

However, having plenty of good bacteria in the vaginal flora can help create a healthy defence against sexually transmitted infections3, 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 good intimate health doesn’t require strong products to keep it clean. Hot water and some optional unscented soap is 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 species4. 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 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.


You may not realise it, but stress can also disrupt the microbiome, both in the gut and the vagina5. 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 though, 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 probiotic at this time, to help keep the vaginal microbiome well supported.

Woman holding tummy

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

How you can 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.
  • Don’t use scented feminine products or perfumed toilet paper.
  • Take a probiotic daily. It is recommended to look for one containing 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 tight clothing and synthetic fabrics against your skin.he
  • 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 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. 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
  4. 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,
  5. 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