Probiotic supplements, which sport beneficial bacteria, are practically synonymous with gut health these days. Though the research is still iffy on how certain types could ease tummy troubles, there’s logic behind the hype: A gut microbiome that’s off-kilter, or running relatively low on those supportive critters, is linked with GI (and other) woes. The same type of thing can happen with the community of microbes in the vagina; when it’s out of whack, you can wind up with an infection and symptoms like itch and discharge. So it’s no wonder plenty of probiotics—both in the form of oral supplements and suppositories you slide into your vagina—now purport to infuse this organ with good bugs too. These days, there’s no shortage of products that claim to do everything from “maintain your vaginal health” to “replenish microflora” and “eliminate odor.”

To be clear, some of these would-be benefits are just drawn from the age-old marketing playbook of preying on women’s insecurities. Contrary to what they might imply, your vagina does not inherently need special maintenance or preventative care in the form of a daily product—in fact, experts agree that if you’re feeling just fine down there, you’re better off not intervening. (And remember: Healthy vaginas naturally have an odor that isn’t exactly fresh or floral.) But what if you are dealing with a hurting vagina—say, one prone to yeast infections (an excess of a fungus called Candida) or bacterial vaginosis (an overload of not-so-great bacteria)? Some vaginal probiotic claims suggest they could offer support.

The research, however, is far from definitive. Like the probiotics claiming to heal your gut, vaginal ones haven’t undergone the stringent safety and efficacy testing necessary for FDA approval. Yes, there are a handful of studies, albeit small ones, that suggest probiotics may help clear or slash recurrence of BV and possibly yeast. (This research shows they may be especially effective in folks who take them with the standard treatment—an antibiotic for BV or an antifungal for yeast.) But it’s important to note many of these trials were funded by probiotics companies or lacked consistent follow-up with participants, among other parameters of quality research, which makes them tricky to trust, Caroline Mitchell, MD, MPH, director of the Vulvovaginal Disorders Program at Massachusetts General Hospital, tells SELF. Not to mention, they run the gamut in terms of which probiotic species participants used, the dose, whether they took it orally or vaginally, and how long they were on it, all of which complicates drawing concrete conclusions.

And yet, these findings aren’t nothing—particularly when you consider that “medicine has very few solid science-based answers about vaginal health,” Dr. Mitchell says. (You can blame good ol’ sexism for that.) Case in point: “Our treatment for recurrent bacterial vaginosis is terrible,” she says, noting that we’ve relied on the same two categories of antibiotics (metronidazole and clindamycin) to resolve it since the 1980s, and a whopping 50 to 80% of people with BV get another infection within a year of treatment. The antifungals for yeast work a bit better, FWIW, but as many as 28% of people still wind up with recurrent yeast infections. And if you’ve been plagued by repeat appearances of either, you know how the constant itching, burning, and discharge can wreck your quality of life. It makes sense why you might turn to probiotics, even if the science is still catching up.

The good news is, experts like Dr. Mitchell are also optimistic about vaginal probiotics—future research could help unlock their potential to tweak our vaginal ecosystem for the better. But before you click “add to cart,” read on to learn what we do (and don’t) know about using these encapsulated bugs for vaginal health, and when, if ever, it may be worth ingesting or inserting them.

To understand why probiotics could theoretically “balance” your vaginal microbiome, it’s helpful to know how it can get messed up in the first place.

When it comes to your gut, an unbalanced microbiome is typically marked by a dearth of variety—a few bad actors have seized control, and taking a probiotic filled with good guys could ostensibly repopulate things for a healthier overall mix. But your vagina is totally different, Smita Gopinath, PhD, an assistant professor of immunology and infectious diseases at Harvard T.H. Chan School of Public Health who studies the vaginal microbiome, tells SELF. The fewer species present, “the stronger and more resilient it is,” she says. Specifically, what you want to see is “all Lactobacillus, all the time, and primarily Lactobacillus crispatus,” Dr. Mitchell says. These bacteria pump out lactic acid, which keeps the pH of your vagina in the acidic zone (roughly 3.8 to 5) and kills off or prevents the overgrowth of microbes like yeast and various harmful bacteria.

The problem is, those crucial lactobacilli are delicate creatures. Plenty can disrupt this community: scented or otherwise harsh hygiene and menstrual products; lubes containing glycerin; antibiotics; smoking; tight or sweaty clothing; hormonal changes like pregnancy and menopause; certain contraceptive methods; and sexual activity—particularly with a new person, or switching between partners. And that’s just naming some of the most common suspects.

In the face of any of these disruptions, you can wind up with a vaginal microbiome that’s relatively lacking in lactobacilli. This allows other organisms to set up shop and overproduce—like yeast, for instance, or a bunch of bad-guy bacteria, the latter of which paves the way for bacterial vaginosis and symptoms like irritation, burning, fishy odor, and discharge in some people. So folks who get these infections could benefit from a vaginal probiotic that reestablishes a “lactobacilli-dominant environment,” Dr. Gopinath explains. (Worth noting: You can have non-lactobacilli bacteria floating around in your vagina and be asymptomatic for reasons that aren’t clear—but again, there’s no evidence-backed reason to take a vaginal probiotic if you’re symptom-free.)

The tricky part is, ingesting or inserting the good bugs doesn’t necessarily restore equilibrium.

The simplicity of the vaginal microbiome—the more lactobacilli, the better—might make it seem like you could just load up on probiotics featuring these good bugs and voilà: A balanced vagina is yours. But in practice, there are some real barriers to these lactobacilli actually making it to your vagina and most importantly sticking around long enough to dominate the local community.

For starters, “the plausibility of something that you take by mouth getting to your vagina is quite low,” Dr. Mitchell says. Which makes sense: Those buggers would have to traverse the harsh environment of your stomach and intestines while remaining alive, reach your perineum (the skin between your anus and vagina), and ultimately scooch over to your vagina. Research suggests that this route is unlikely to create any real microbiome change.

Using a vaginal suppository majorly shortens that pathway, hence why much of the recent research on the vaginal microbiome has coalesced around these kinds of products. And yet, a couple studies suggest that even inserting Lactobacillus this way doesn’t always help these good bugs colonize the vagina or improve BV outcomes. The reason why may have to do with things like the viability of the bugs (a.k.a. whether they’re actually still alive in the product) and the particular species of Lactobacillus used, among other factors. As Dr. Mitchell points out, plenty of vaginal probiotics on the market feature kinds of lactobacilli that are commonly found in your gut but aren’t so predominant in the vagina, like L. rhamnosus, L. reuteri, and L. acidophilus—so it’s unlikely that inserting these microbes into your vagina would do much.

There may be an FDA-approved vaginal probiotic in the future—but until then experts can’t wholeheartedly recommend you try these.

It makes a lot of sense, in theory, that a suppository packed with the right probiotics, alive and well, could nudge the vaginal microbiome toward health. The best evidence for that, Dr. Mitchell says, is a not-yet-available product called Lactin-V, which includes the primary vagina-centric species of Lactobacillus (L. crispatus) and is currently going through the FDA process to become a prescription drug. Research has shown it significantly reduces BV recurrence—just 30% of people who took a twice-weekly dose of the stuff for 10 weeks after receiving BV treatment wound up getting a repeat infection, compared to 45% of the placebo group. The study also found that the supportive bugs stuck around in people: The specific strain used was detectable in about 80% of participants for the length of the trial.

Still, further research found that only 48% of them maintained that new community of healthy bugs three months later—meaning, the benefits probably waned with time too. Researchers are currently investigating how they can make that colonization last longer; Dr. Mitchell just wrapped a trial of a probiotic that includes multiple strains of L. crispatus, for example, with the idea that distinct strains might latch on better in different people.

As Dr. Gopinath points out, there’s no ideal vaginal probiotic just yet because there’s still plenty we don’t know about the vaginal microbiome, like how we even acquire it during puberty and what lets it stick around through disruptions like menstruation. It’s a tough thing to study because humans are, oddly, the only mammal with a Lactobacillus-dominant vaginal microbial pattern. Mouse models are often used to study the gut microbiome, but there’s no good equivalent for the vaginal one, Dr. Mitchell says. And of course, there’s the persistent problem of getting funding for research on anything involving the vagina, she adds.

So, for now, experts recommend a healthy dose of skepticism when it comes to the available products, which, reminder, haven’t gone through the rigorous testing required for medications. Much like with other supplements, there’s also no guarantee that you’re getting what’s promised on the label and in the stated dose(s), and that any probiotic strains included are even viable, Dr. Gopinath notes. (Nor can you be sure the product is free from random contaminants.) Because vaginal suppositories aren’t technically dietary supplements—you don’t take them by mouth—the regulatory clearance for these is fuzzy, and some are actually marketed as cosmetics, Dr. Mitchell points out, under the pretext of things like “odor control” (which, again, is more sexism than anything else). The bottom line is, it’s hard to know whether these products are safe to put into your body, via any hole, and if doing so will have any positive effect.

The good news is, using a vaginal probiotic is unlikely to cause a negative outcome, Dr. Mitchell notes. Yes, you are inserting a living organism, so there’s a chance it doesn’t play well with the microbes in your vagina, not to mention the slim possibility that you have a sensitivity to an inactive ingredient in the product—but these are rare scenarios. The bigger risk, she says, is using one of these products to self-treat a vaginal issue without knowing what it is. It can be tough to tell different vaginal conditions apart, so it’s best to see your gyno if you’re dealing with any new-to-you symptoms. This way, you can be sure you’re not bypassing the FDA-approved treatment for the problem you’re facing. Even if it is BV or yeast, probiotics aren’t a replacement for the recommended antibiotic or antifungal, respectively; you’d still need to follow the typical regimen for an infection. That said, if you do have confirmed recurrent BV, using a vaginal suppository containing L. crispatus (in between infections) is generally considered low-risk and may be beneficial, Dr. Mitchell says.

Both experts are hopeful that soon they’ll be able to point to an evidence-backed, FDA-approved vaginal probiotic to help with common infections of this organ, BV in particular. As Dr. Gopinath notes, it’s not just about improving quality of life for the many people suffering from repeat hits (though that’s crucial). The abnormal microbial pattern linked with BV is also connected to increased risk for STIs and poor reproductive outcomes, she says: “BV is a risk multiplier, and we really need to start treating it that way.” Only then might there be enough interest and funding to bring the promise of vaginal probiotics to fruition.

Related:

• Can Putting Boric Acid in Your Vagina Treat Relentless Yeast Infections or BV?
• 6 Common Behaviors Ob-Gyns Wish You’d Stop Doing
• How to Prevent UTIs If You Just Keep Getting Them

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