A herbal mouthwash selectively killed off bad bacteria in the mouth while preserving the good strains, according to a new study. It suggests an alternative to conventional mouthwashes, which were found to kill indiscriminately and damage gum tissue.
Evidence is growing about the health-giving properties of good oral bacteria. Prior research has linked disturbances in the oral microbiome to depression, anxiety, autism spectrum disorder, Parkinson’s disease, dementia, and schizophrenia. So it makes sense that we would want to hold on to good mouth bacteria and rid ourselves of the not-so-good.
A new study has examined the effect of using a commercially available herbal mouthwash on oral bacteria, compared with conventional mouthwashes such as PerioGard and Listerine, and found that the former is clearly better for maintaining the microbiome.
The study was funded by the manufacturer of the herbal product, it should be noted. But the research was led by the Rutgers School of Dental Medicine, and has been published in the peer-reviewed journal Frontiers in Oral Health.
“It’s a paradigm shift,” said Georgios Kotsakis, the school’s assistant dean for clinical research and the study’s corresponding author. “We’re moving from eradicating all bacteria to focusing on selectivity. We want to keep the good bacteria alive while targeting the bad.”
The herbal mouthwash the researchers tested was StellaLife VEGA Oral Rinse, which, according to the website, contains the active ingredients azadirachta, calendula, echinacea, and plantago “in homeopathic dilution.”
Does this mean that the ingredients have been diluted so many times that not a single original molecule remains? Not in this case. According to NiH records, this particular oral rinse contains 0.55% of each of these "active ingredients" in a 1X dilution. 1X is the lowest dilution level at which something can be claimed to have homeopathic properties - it's a single 1 part in 10 dilution.
Alternative medicine products like this are not approved by the US FDA for safety and efficacy – but they are required to meet the FDA's "Current Good Manufacturing Practices," which include controls on raw materials, production processes, testing and record keeping. Indeed, StellaLife recalled two batches of Vega mouthwash last year after the FDA detected unacceptable levels of microbial contamination. So the product is not completely unregulated, and despite its homeopathic labelling, it does contain ingredients.
Against this product, the researchers tested 0.12% chlorhexidine gluconate mouthwash (sold as Savacol, Peridex, or PerioGard) and Listerine Cool Mint mouthwash. Saline was used as a control.
Each of the mouthwashes was applied to specific oral bacterial cultures – Streptococcus oralis, Streptococcus gordonii, Veillonella parvula, Fusobacterium nucleatum, and Porphyromonas gingivalis – and bacterial growth was assessed. The effectiveness of the mouthwashes was also tested against biofilms, bacterial communities encased in a self-produced slimy substance that adheres to surfaces and can provide resistance to antibiotics and the immune system. And, finally, the mouthwashes were assessed for their damage to human gum cell cultures.
StellaLife’s oral rinse exhibited a selective antimicrobial action. It inhibited disease-causing bacteria F. nucleatum and P. gingivalis but spared beneficial bacteria S. oralis, S. gordonii, and V. parvula. In contrast, the chlorhexidine and Listerine mouthwashes killed both harmful and helpful microbes indiscriminately.
In lab models of bacterial species, the herbal oral rinse reduced harmful bacteria while maintaining a biofilm of normal, healthy bacteria. In more complex biofilms from real clinical samples, the herbal wash effectively disrupted bad biofilms and reduced pathogenic bacteria compared to chlorhexidine and Listerine.
When the products were tested on human gum cells, chlorhexidine caused significant cell death, and Listerine caused moderate damage. StellaLife showed minimal toxicity, preserving cell structure and viability, suggesting it was more compatible with human tissues.
“These good bacteria have important functions,” Kotsakis said. “They synergize with your tissues. They actually kill some of the bad bacteria themselves.”
There are limitations to the study. Most results are from controlled laboratory models, not live human subjects, so real-world conditions may differ. And while biofilm volume and viability were measured, the detailed bacterial composition post-treatment wasn’t evaluated by, say, DNA sequencing. Also, the exact way that StellaLife’s oral rinse selectively kill pathogens and spares good bacteria remains unclear. Finally, the experiments mostly covered hours to days; longer-term effects on the oral microbiome weren’t assessed.
Despite these limitations, the study’s findings could be instructive. They suggest a move away from a scorched-earth, carpet-bombing approach to oral hygiene, such as that provided by conventional mouthwashes, to one that is more selective and protective of good oral bacteria.
“Randomized clinical trials are the next step,” said Kotsakis. He offered this piece of advice: “If you’re brushing and flossing like a dentist – regularly and perfectly – you may not need a mouthwash, but in reality, even the best of us can miss some surfaces during cleaning at home.”
The study was funded by StellaLife and was published in the journal Frontiers in Oral Health.
Source: Rutgers University
Editor's note: This story was updated on July 3, 2025 to include more information about the product's ingredients, its status as an alternative medicine not approved for safety or efficacy by the FDA, its minimal levels of "homeopathic dilution," relevant manufacturing standards and Stellalife's 2024 recall. We also added an extra mention of Stellalife's funding of the study, earlier in the piece.
"The study was funded by StellaLife."
Not saying it has no merit, But I won't trust any study funded by the same people it apparently benefits.
It might do what it says it's doing, but not for the reasons it's saying. I like the premise of selective killing of bad bacteria, but not sure how any ingredient could actually do that in such a complicated place as the mouth.