Vaginal Probiotics: What Does the Science Say?

Dr Natalie Hutchins
3 days ago
9 min read

We talk a lot about balance when it comes to our bodies and in the vagina, that balance is maintained by a complex ecosystem of microbes called the vaginal microbiome. When that balance is disrupted, the symptoms can be hard to ignore: unusual discharge, odour, irritation, or recurring infections like thrush or bacterial vaginosis (BV).

In recent years, researchers have started to explore the potential of vaginal probiotics; live, beneficial bacteria that can help restore a healthy vaginal microbiome. But what does the science actually say? Are they effective, and if so, which ones should you be using?

This article breaks down how vaginal probiotics work, which strains are best studied, and how to choose a product that matches your needs.

What are vaginal probiotics?

Probiotics are live, beneficial bacteria that provide health benefits when taken in the right amount.1 Vaginal probiotics help restore balance in the microbiome and prevent infection.2 They can be taken orally (as capsules or powders) or applied directly to the vagina (as suppositories, tablets or gels).

Most vaginal probiotics contain strains of Lactobacillus, the dominant bacteria in a healthy vagina.3 Strains are usually taken from healthy donors via vaginal, gut or breast milk samples. Then, individual strains are grown in labs and freeze-dried to preserve their strength before being added to supplements.4

You’ll usually see a number on the label listed in CFUs (colony-forming units). This tells you how many live bacteria are in each dose.5 They’re called “live” because the bacteria are still active when you take them and able to survive long enough to reach the vaginal lining and do their job.

What’s the difference between probiotics and prebiotics?

● Probiotics:

Live, friendly bacteria that help maintain or restore balance in your microbiome.

● Prebiotics:

The fibre or nutrients that feed those good bacteria (think of them like fertiliser for your microbiome).

Some supplements combine both. These are called synbiotics, and the combination can help the probiotics survive longer and work more effectively.6

How do vaginal probiotics work?

Vaginal probiotics support your body’s natural defences by boosting the population of Lactobacilli in the vagina. Here’s how they work:

1. They keep your vagina slightly acidic

Lactobacilli feed on glycogen, a natural sugar in the vaginal lining. As they break it down, they produce lactic acid, which helps keep vaginal pH low (around 3.5 to 4.5).7 This acidic environment makes it harder for pathogens (like Gardnerella or Candida) to grow.

2. They produce natural defences

Some strains of Lactobacillus make compounds that kill or weaken harmful microbes. These include:

● Hydrogen peroxide, which has mild disinfecting properties.

● Bacteriocins, which are proteins that act like natural antimicrobials.

● Biosurfactants, which stop pathogens from sticking to the vaginal walls.8

3. They break down microbial shields

Some infections are hard to treat because bacteria and fungi can form a biofilm, a kind of sticky shield that protects them against antibiotics and antifungals.9 Certain probiotics can help break down these biofilms, making infections easier to treat and less likely to return.6

4. They calm inflammation

A disrupted vaginal microbiome can trigger irritation and inflammation. Some probiotic strains help soothe this by lowering inflammatory markers and increasing calming immune signals.4 This immune support may also make the vaginal lining more resilient to infection.

5. They help good bacteria stick around

For probiotics to work, they need to stick to the vaginal walls. This is called colonisation. When good bacteria latch on, they help form a protective barrier that makes it harder for harmful microbes to grow. Strains that can effectively colonise the vagina are more likely to have lasting effects.7

Are probiotics backed by science?

The short answer is: yes, when the right strains are used for the right reasons.

Not all probiotics are the same. Each strain (specific type within a species) can behave differently in the body. When it comes to vaginal health, only a handful of strains have been properly studied in randomised controlled trials.

We need more robust research before we can make certain claims about these strains, but here are the ones that show the most promise:

● Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14These two strains are often paired together and are some of the most studied probiotics for vaginal health.10 Multiple studies suggest they can help restore lactobacillus dominance and improve treatment outcomes for BV and thrush.11 However, a recent trial in China found no significant benefit, suggesting ethnic microbiome differences might play a role.12

● Lactobacillus crispatus CTV-05This strain is one of the most protective species in a healthy vaginal microbiome and is especially good at producing lactic acid, keeping the vaginal pH low and protective. One study found a significantly lower rate of BV recurrence using this strain, compared to a placebo.13

● Lactobacillus acidophilus KS400Often used in vaginal pessaries, this strain helps rebuild protective bacteria after infection and supports healing.11 One study found that use after antibiotics led to improved healing and reduced infection recurrence.14

● Lactobacillus gasseriKnown for its anti-inflammatory effects, this strain may be especially helpful when inflammation or hormonal changes disrupt the vaginal microbiome, like during menopause or in cases of endometriosis.4

● Lactobacillus johnsoniiHelpful in managing recurrent thrush, this strain has been shown to break down Candida biofilms (protective layers that make yeast harder to treat) and support a healthy immune response.15

● Lactobacillus plantarumA versatile strain shown to help restore balance in the vaginal microbiome and reduce common BV symptoms like discharge and odour.16

What can I use probiotics for?

While probiotics aren’t a magic cure, they’ve been shown to help treat and prevent several vaginal health issues, especially when used consistently alongside other treatments. Here's what the research tells us.

Bacterial Vaginosis (BV)

BV happens when Lactobacilli are outnumbered by anaerobic bacteria like Gardnerella or Prevotella, leading to symptoms like odour, discharge and discomfort.

Probiotics aren’t a replacement for antibiotics, but they can make BV treatment more effective. A 2024 review of 35 clinical trials found that women who took probiotics alongside antibiotics had higher cure rates and were much less likely to have BV return.11 In fact, probiotics cut recurrence by more than half in some cases, and vaginal probiotic worked particularly well.

The biggest benefit of probiotics for BV is to help rebuild the vaginal microbiome and stop BV from coming back.

Thrush (Vulvovaginal Candidiasis)

Caused by an overgrowth of Candida yeast, thrush leads to itching, burning, and thick discharge, and for some, it keeps coming back.

Probiotics can help, but they work best alongside antifungal treatment, not instead of it. Certain strains (like L. johnsonii, L. reuteri, and L. acidophilus) have been shown to suppress Candida growth, break down protective biofilms and support a healthy vaginal environment.17

A recent review grouped probiotic use into three key areas:

When used alone, probiotics had mixed results for treating thrush.
When used alongside antifungal medication, probiotics worked better, improving recovery time and helping to reduce symptoms.
When used as prevention, probiotics were most effective. In women with recurring infections, probiotics reduced thrush coming back by up to 64%.18

So, while probiotics aren’t a stand-alone fix, they can be a valuable part of preventative care alongside antifungals.

HPV and STIs

The vaginal microbiome plays a key role in the body’s ability to protect itself against sexually transmitted infections, including human papillomavirus (HPV).19

While more evidence is needed, early research suggests probiotics may help the body clear high-risk HPV. One study found women taking L. crispatus had lower HPV viral loads and less vaginal inflammation, supporting the body’s immune response and ability to clear HPV.20

Pregnancy

Pregnancy comes with big hormonal shifts that can affect both your vaginal and gut health. Infections like thrush are more common, and your microbiome can change in ways that leave you feeling off.

Some research suggests probiotics might help. In one study, pregnant women taking a branded probiotic had lower Candida levels, more Lactobacillus, and more stable gut health.21 Other studies suggest possible benefits for things like gestational diabetes, vaginal infections, and even pre-term birth, but results vary depending on the strain.22 If you’re pregnant and thinking about taking probiotics, make sure to choose one that’s been specifically tested on pregnant women. Not all products are designed with pregnancy in mind, so it’s always best to check with your doctor first.

Fertility and IVF

Early research has linked a healthy vaginal microbiome to better fertility outcomes. In IVF patients, oral probiotics have been shown to help restore microbial balance, potentially improving the chances of implantation and pregnancy.22

Menopause

As oestrogen levels decline, Lactobacilli also decrease, raising the pH and increasing the risk of dryness and infection. Early research suggests probiotics may help restore comfort and reduce inflammation, especially strains like L. gasseri and L. jensenii.4

Endometriosis

In people with endometriosis, L. gasseri has been shown to reduce pelvic pain and inflammation. Early studies suggest this may be down to its ability to support immune balance in the reproductive tract.4

How do I choose the right probiotic for me?

Vaginal probiotics can be a helpful addition to your health routine, but not all products are created equal. So, here's what to look for:

1. Check for specific strains

A good probiotic should list the full strain name, not the species. For example, L. rhamnosus GR-1 or L. crispatus CTV-05. These letter/number codes matter because they show that the exact strain has been tested in clinical research.

2. Look for a high enough dose (CFU)

CFU stands for colony-forming units. This tells you how many live bacteria are in each dose. Most studies use at least 1 to 10 billion CFUs per day (written as 10⁸ - 10¹⁰). Any less than that probably won’t make much difference.

3. Choose the right format for you

Oral probiotics (taken by tablet or powder) support the vagina through the “gut-vagina axis”, where gut microbes influence vaginal microbes over time.23 This route may be slower, but it also supports digestion and overall immune health. Meanwhile vaginal probiotics go straight to the source via tablets, suppositories or gels. They work more quickly, especially if you’re dealing with an active infection.

4. Pay attention to storage and stability

Some probiotics need to be kept in the fridge, while others are shelf-stable. Look for “viable until expiry” on the label to make sure the bacteria will stay alive and effective for as long as possible.

5. Match your probiotic to your specific concern

Here’s a rough guide:

● BV: L. crispatus, L. plantarum, L. rhamnosus

● Thrush: L. reuteri, L. johnsonii, L. acidophilus

● HPV and Inflammation: L. crispatus

● Fertility and Pregnancy: multistrain blends

● Menopause: L. gasseri, L. jensenii

Making sense of the evidence

The science is still evolving, but the message is clear: the vaginal microbiome matters. When it’s in balance, we’re more protected against infection, irritation and discomfort, especially during times of hormonal change.

Probiotics aren’t a magic fix, but they can offer meaningful support. Early research shows that certain strains can reduce symptoms, prevent recurrence and help restore a healthy microbiome, particularly for those taking antibiotics or dealing with chronic infections.

The key is choosing the right strain, in the right format, for the right reason. Not every probiotic will work for everybody. But for many women, they offer a simple and affordable way to support their body’s natural defence mechanisms.

As always, speak to a trusted healthcare professional if you’re unsure. And remember: good vaginal health isn’t just about fixing problems, it’s about supporting long-term balance in a way that works for you.