What Is Lactobacillus Crispatus?

When it comes to maintaining a healthy vaginal microbiome, not all bacteria are created equal. You’ve likely heard that Lactobacillus are the stars of the vaginal microbiome, working to keep pathogens at bay and reduce your risk of infections. One of the most powerful and protective species found in the vagina is Lactobacillus crispatus (L. crispatus), a true unsung hero of vaginal health.

Let’s explore what makes L. crispatus so special, how it supports vaginal balance, and who stands to benefit most from boosting their levels of this important microbe.

The role of Lactobacillus crispatus in vaginal health

Lactobacillus crispatus may be microscopic, but its impact on vaginal health is enormous. It’s a rod-shaped, lactic acid–producing bacteria commonly found in both the vaginal microbiome and gastrointestinal tract. Among the many types of vaginal bacteria, L. crispatus is considered a dominant and protective member of a healthy vaginal microbiome. The presence of Lactobacillus crispatus isn’t just helpful, it’s often essential for long-term vaginal health.

By producing lactic acid, Lactobacillus crispatus maintains a vaginal pH that is typically below 4.5. This acidic environment helps prevent the growth and attachment of vaginal pathogens, such as Gardnerella vaginalis, the primary cause of bacterial vaginosis (BV). Alongside lactic acid, it produces hydrogen peroxide and bacteriocins — natural antimicrobial agents that can kill or inhibit the growth of both bacteria and fungi, including Candida albicans.

Interaction with vaginal epithelial cells

Beyond its effects on the microbiome, Lactobacillus crispatus plays a role in maintaining vaginal health thanks to a direct relationship with the cells that line the vaginal wall (vaginal epithelial cells). It can actually form a biofilm of its own, which prevents other pathogenic biofilms from forming. 

This species plays a crucial role in maintaining a strong mucosal barrier by producing metabolites that promote vaginal epithelial health and integrity. It also prevents pathogens from adhering to these cells, which is a critical first step in infection.

In laboratory and animal models, Lactobacillus crispatus has been shown to enhance gene expression related to immune defense, while simultaneously calming inflammation. It reduces the activation of immune cells like dendritic cells, helping to avoid an overreaction to normal stimuli and keeping the vaginal environment in a more balanced, less inflamed state.

These combined effects help prevent vaginal infections before they start, while supporting comfort and resilience in the vaginal tissue itself.

Bacterial diversity and Lactobacillus crispatus

Unlike in the gut, less bacterial diversity is usually a good thing when it comes to the vagina. Basically, too many cooks spoil the broth. A healthy vaginal microbiome is typically dominated by just one or two species of Lactobacilli, with L. crispatus being one of the most desirable.

When Lactobacillus crispatus is dominant, it helps maintain a balanced, stable microbiome that resists disruption. In contrast, when it's absent or depleted, more diverse (but less protective) bacteria often take its place. This condition, known as community state type IV, is associated with an increased risk of bacterial vaginosis, inflammation, and even adverse reproductive outcomes like preterm birth.

L. crispatus also works cooperatively, or sometimes competitively, with other vaginal microbes. For example, it often interacts with Lactobacillus iners, another common species. While L. iners is present in many women, it’s not as strongly protective as Lactobacillus crispatus, and high levels of L. crispatus are generally a better sign of long-term vaginal stability.

By supporting a low-diversity, Lactobacilli-dominated microbiome, Lactobacillus crispatus helps ensure that harmful bacterial species (like BV-associated bacteria) don’t have the opportunity to take over.

Who benefits most from L. crispatus?

While Lactobacillus crispatus is beneficial for many women, it’s especially helpful for those experiencing or recovering from disruptions to their vaginal microbiota.

Women who have recurrent bacterial vaginosis benefit the most from taking Lactobacillus crispatus. 

In addition to women with bacterial vaginosis, others who may benefit include those who have recently experienced antibiotic use, menstruation, sexual activity, or other disruptions to the vaginal microbiota. If you’re at higher risk of infections or if your vaginal microbiome lacks Lactobacillus crispatus, supplementation may help rebalance your ecosystem and reduce inflammation.

Women who have a microbiome without enough Lactobacillus species (known as community state type IV) may find it helpful to supplement with Lactobacillus crispatus. This microbiome state is linked to a higher risk of bacterial vaginosis, yeast infections, and inflammatory conditions. Supplementation is most effective when Lactobacillus crispatus is depleted or absent — which can be determined through vaginal microbiome testing, like Evvy’s.

However, there’s no current evidence supporting routine supplementation in asymptomatic women who already have a stable, Lactobacillus crispatus-dominated vaginal microbiome. In these cases, your body is likely already doing exactly what it’s supposed to.

Supporting your microbiome with Lactobacillus crispatus

If you're looking to support your vaginal microbiome after bacterial vaginosis, antibiotics, or another disruption, Evvy Women’s Complete Probiotic is formulated with Lactobacillus crispatus and four other clinically studied strains to help restore balance from the inside out. Unlike one-size-fits-all probiotics, Evvy’s 3-in-1 formula is designed specifically with the vaginal, gut, and urinary microbiomes in mind — because your microbiomes don’t work in isolation, so neither should your probiotic. 

FAQ

What is Lactobacillus crispatus used for?

Lactobacillus crispatus is a naturally occurring bacterium found in the vaginal microbiota. When taken as a supplement, it can support and restore a healthy vaginal microbiome, especially in women with recurrent bacterial vaginosis or after disruptions like antibiotics, menstruation, or sex. It helps maintain a low vaginal pH, inhibits the growth of harmful bacteria and yeast, and strengthens the vaginal barrier by producing protective compounds like lactic acid and hydrogen peroxide. It also modulates inflammation and promotes immune balance in the vaginal tissue.

Is Lactobacillus crispatus safe for pregnancy? 

Using Lactobacillus crispatus during pregnancy is generally considered safe, especially when taken vaginally to help prevent recurrent bacterial vaginosis after antibiotics. Clinical studies of vaginal L. crispatus haven’t shown any serious side effects, even in women of reproductive age, including those who are pregnant. Although most studies haven’t focused specifically on pregnant women, the existing data suggest no added risk. Because bacterial vaginosis is linked to pregnancy complications, using L. crispatus after treatment may be helpful, as long as the product is high quality and used as directed. Nevertheless, you should consult your healthcare provider before taking Evvy Women’s Complete Probiotic if you’re pregnant.