Vaginal Flora

The vaginal flora is the bacteria that live inside the vagina. The normal vaginal flora is dominated by various lactobacillus species.

Lactobacilli help to keep the vagina healthy by producing lactic acid, hydrogen peroxide, and other substances that inhibit the growth of yeast and other unwanted organisms. They maintain the vagina at a healthy pH of around 4.

This mildly acidic environment helps protect against infection. So do the other substances they produce. These bacteria are an important part of a healthy vaginal ecosystem.

Female doctor going over test results with patient
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Why Vaginal Flora Is Important

A hallmark of bacterial vaginosis (BV) is the disruption of this normal vaginal flora and a loss of lactobacilli. This can not only be unpleasant in and of itself. It can also leave a woman more susceptible to HIV and other sexually transmitted infections.

Bacterial vaginosis is actually caused by an overgrowth of bacteria that normally exist at low levels in the vagina. When the lactobacillus population is disrupted, these bacteria take over.

The bacteria associated with BV make a number of volatile amines. These chemicals are what cause the distinctive odor associated with BV. This odor tends to be stronger after sex, particularly unprotected sex, because the amines become smellier at the higher pH associated with semen.

However, despite the association, BV is not caused by sperm. In fact, the greatest evidence for sexual transmission of bacterial vaginosis is in lesbians.

It's not clear whether BV can be transmitted during vaginal intercourse. BV is most often diagnosed by a test called a wet mount.

Restoring Healthy Vaginal Flora

One of the difficulties in treating BV and related conditions, such as yeast infections, is figuring out how to restore the normal vaginal flora. Sometimes the bacterial populations return to normal proportions after treatment. Other times they don't.

In order to help restore a lactobacillus-dominated flora, a number of researchers are looking at probiotic pills and suppositories. These treatments would contain lactobacillus species.

The hope is that those bacteria would grow and recolonize the vagina. To date, results have been somewhat positive, if preliminary. Still, if they're borne out, probiotics may be a new way to improve vaginal health and restore healthy vaginal flora.

Frequently Asked Questions

  • Can you treat vaginal infections with probiotics?

    No. While there's some research showing that certain types of probiotics may help with bacterial vaginosis, there’s not enough to show that they're totally effective. Probiotics showing the most promise are those containing Lactobacillus rhamnosus GR-1. However, you should speak to your healthcare provider before trying it since it may create an imbalance in your gut bacteria when taken orally.

  • How can you maintain the pH of your vagina?

    Diet plays an important part. Eat less sugar, which can raise pH and put you at risk for a yeast infection. Because garlic and apple cider vinegar have antibacterial and antifungal properties, they may help as well. Other tips: Avoid douching and wear underwear that is made of natural, breathable material like cotton.

  • Do women get more vaginal infections after menopause?

    You may have a greater risk of vaginal infection after menopause because of a drop in estrogen, which leads your vagina to become thinner and drier. This may make you more prone to infection. 

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Miller EA, Beasley DE, Dunn RR, Archie EA. Lactobacilli dominance and vaginal pH: why is the human vaginal microbiome unique?. Front Microbiol. 2016;7:1936. doi:10.3389/fmicb.2016.01936

  2. Lobo, RA, Gershenson, DM, Lentz, GM, Valea, FA. Comprehensive Gynecology. New York, NY: Elsevier Health Sciences; 2016.

  3. Heczko PB, Tomusiak A, Adamski P, et al. Supplementation of standard antibiotic therapy with oral probiotics for bacterial vaginosis and aerobic vaginitis: a randomised, double-blind, placebo-controlled trial. BMC Womens Health. 2015;15:115. doi:10.1186/s12905-015-0246-6

  4. Harvard Health Publishing. Should you use probiotics for your vagina?

  5. Rizg WY, Hosny KM, Elgebaly SS, et al. Preparation and optimization of garlic oil/apple cider vinegar nanoemulsion loaded with minoxidil to treat alopecia. Pharmaceutics. 2021;13(12):2150. doi:10.3390%2Fpharmaceutics13122150

  6. Dalal P, Agarwal M. Postmenopausal syndrome. Indian J Psychiatry. 2015;57(6):222. doi:10.4103/0019-5545.161483

Additional Reading

By Elizabeth Boskey, PhD
Elizabeth Boskey, PhD, MPH, CHES, is a social worker, adjunct lecturer, and expert writer in the field of sexually transmitted diseases.