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Antimicrobial Mouthwash: Helpful or Harmful?
- lizlaneyrdh
- Apr 9
- 6 min read
Updated: May 28
As a dental hygienist, one of the main home care products I hear about most is mouthwash. In school, we were taught that nothing can beat Listerine (besides Chlorhexidine), and wiping out as much bacteria in the oral cavity as possible is the goal and prevents the most disease. However, years of research now support the fact that long-term use of antimicrobial mouthwashes is detrimental to the body at multiple levels. Even so, dentistry is wildly behind in updating protocols to avoid adverse oral and systemic side effects of using such products.
Keep reading to learn how and why long-term use of antimicrobial mouthwashes (AMW) is no longer a recommended oral care routine.
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Overall, research has shown that AMW is effective in reducing plaque and inflammation and improving bad breath (i.e., halitosis). However, the concern is not their level of effectiveness but rather the severity of the negative side effects that occur as a result of long-term use of AMW.
First, the biggest impact of long-term use of AMW is seen in the disruption of the oral microbiome, a process which is known as dysbiosis. Within the oral microbiome are 700+ species of bacteria, both commensal (i.e., healthy) and pathogenic (i.e., harmful).
Use of AMW removes not only the pathogenic species but also the beneficial, commensal bacterial species that are required to prevent the overgrowth and maturation of more harmful pathogens. As a result of a ‘clean’ mouth, opportunistic, harmful pathogens easily overtake healthy bacterial strains and are able to repopulate, mature, and spread to other areas of the oral cavity and body. With continued colonization and spread of these harmful pathogens, a systemic inflammatory response is initiated, and several disease processes begin.
Oral dysbiosis is known to increase susceptibility to
infections such as oral thrush and periodontal diseases
and can increase caries risk [7].
Additionally, the use of AMW contributes to xerostomia (i.e., dry mouth) due to often being alcohol-based.
As with the consumption or use of any alcohol-based product, salivary production decreases
As discussed in my blog post all about saliva, with less salivary flow, there is a loss of salivary clearance, a decrease in salivary buffering capacity, and alterations in oral pH levels, which in turn increase the risk of disease even further and can even alter taste sensations
Yet another potential side effect of long-term use of AMW, especially those that are alcohol-based, is an increased risk for oral cancer.
The research on this risk does show conflicting results, so no correlation or causation has been established [2]. However, regular consumption of alcohol is known to increase risk of systemic cancers in general, so one may assume that regular exposure to alcohol-based mouthwash could also increase risk to the exposed oral tissues due to alcohol being a known carcinogen.
Further, one of the more widely unknown yet concerning side effects of AMW is the impact it can have on blood pressure, immunity, cognition, and systemic inflammation [6].
Research has shown that long-term use of AMW reduces the production of nitric oxide, which is a signaling molecule involved in modulating several physiological responses within the body, including the following [6]:
Maintenance of blood pressure via vasodilation
Stimulation of the host defenses via the immune system
Support of memory and learning via neurotransmission
Improvement in wound healing via the promotion of cellular growth and repair
Support of respiratory health via bronchodilation & oxygen delivery
Support of gastrointestinal (GI) health via nutrient absorption
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“Several human studies have confirmed the association between the frequent use of antimicrobial mouthwashes and an increase in systolic blood pressure ranging from 2 to 5 mm Hg [2].
This becomes relevant when it is known that even a sustained modest 2-mm Hg elevation in blood pressure can significantly increase the risk of mortality from stroke or ischaemic heart disease [2].”
Nitric oxide is also produced naturally in the body, especially in the paranasal sinuses during nasal breathing patterns. Additionally, nitric oxide levels can also be increased by following proper diet recommendations as certain foods rich in nitrates and nitrites, when consumed, result in systemic production of nitric oxide [1].
Foods that promote nitric oxide levels to increase:
Beets
Garlic
Leafy greens
Dark chocolate
Citrus fruits
Pomagranate
Nuts and seeds
Watermelon
Meat and poultry
For individuals with low nitric oxide levels, supplemental products are available, but it's important to discuss any changes in supplements or medications prior to making changes as high doses of nitric oxide can be harmful.
*Below are some nitric oxide products available. Again, please consult a healthcare professional before taking nitric oxide supplements or changing any dietary and lifestyle habits.
Although dentistry has normalized and praised daily use of mouthwashes to “kill 99.9% of oral bacteria” for decades, we now have a new, research-supported standard of care to follow, and it's time to update our protocols!
For anyone concerned about the risks discussed here, consider consulting with a dental professional to explore alternative oral care options that maintain a healthy balance in your oral microbiome.
In summary, negative side effects seen with the use of AMW are as follows:
Oral microbiome dysbiosis
Xerostomia
Altered taste sensations
Decrease in nitric oxide levels
Increase in blood pressure
Increased risk of oral diseases
Gingivitis
Periodontitis
Dental caries
Oral cancer
Tooth staining
I have created a short guide for ingredients to avoid and products that support the oral microbiome. See below for more!
Ingredients to avoid in long-term-use oral care products:
Alcohol: drying, pro-inflammatory
Cetylpyridinium chloride (CPC): staining
Essential oils: antimicrobial
Chlorhexidine gluconate (CHG): broad-spectrum antiseptic, staining
Chlorine dioxide: antimicrobial
Sodium chlorite: antimicrobial [4]
Hydrogen peroxide: antimicrobial
Sodium lauryl sulphate: surfactant, often irritates oral tissues
Did you know: Listerine antimicrobial mouthwashes contain 26.9% alcohol!
Even the non-alcohol-based Listerine is considered antimicrobial due to also being essential-oil-based; Thus, Listerine and similar products are not recommended for long-term, daily use.
If you choose to use a mouthwash as part of your oral care routine, I recommend use of one of the following brands as they are supportive of the oral microbiome, non-alcohol-based, and have a lower impact on oral pH level fluctuation.
A better alternative to the use of AMW is the use of oral probiotics. Like systemic probiotics, oral probiotics contain live species of healthy bacteria that promote favorable conditions within the oral cavity that support health instead of disease.
A few of my favorite oral probiotic brands are listed below.
As a dental professional, I am able to provide product discounts as follows:
BioGaia: 10% off a 3-pack bundle of BioGaia Prodentist on Amazon or Biogaia.com - THREEPACK10
Burst Oral Care: All products at burstoralcare.com: LizLaneyRDH
For those who use mouthwash as a way to treat bad breath, a better and more effective alternative is available - tongue scraping! This focuses on removal of harmful bacterial loads coating the top of the tongue, which allows healthy bacteria to flourish and reduces the amount of volatile sulfur compounds (VSC) released by pathogens known to cause halitosis.
Here are a few options for tongue scrapers:
For patients with xerostomia and/or high caries risk, I highly recommend OraBio’s Periovance Dry Mouth Gel to support oral moisture and pH levels during the daytime and while sleeping.
If you’d like a more personalized recommendation for what products are best for you to use, I highly recommend the Bristle Oral Microbiome test - an at-home salivary diagnostics test that gives individualized results showing which bacteria are present, both the good and the bad, and what oral care products are recommended based on the results.
Check out my other blog posts to learn more about oral-systemic health!
For links and discounts on products mentioned in this post, check out my Resources page.
Talk soon,
Liz Laney, BSDH, RDH
Oral-Systemic RDH & Educator
Have questions about biofilm and its impact on oral and systemic health? Check out the forum and start a conversation!
Sources
Ajmera R. The 10 best foods to boost nitric oxide levels. Healthline. June 12, 2024. https://www.healthline.com/nutrition/nitric-oxide-foods#red-wine.
Alrashdan MS, Leao JC, Doble A, McCullough M, Porter S. The effects of antimicrobial mouthwashes on systemic disease: What is the evidence? International Dental Journal. 2023;73:S82-S88. doi:10.1016/j.identj.2023.08.012
Brookes Z, Teoh L, Cieplik F, Kumar P. Mouthwash effects on the oral microbiome: Are they good, bad, or balanced? International Dental Journal. 2023;73:S74-S81. doi:10.1016/j.identj.2023.08.010
Farrar S, Castronova S. The active ingredients behind oral rinses. RDH Magazine. June 8, 2024. https://www.rdhmag.com/patient-care/article/55020259/the-active-ingredients-behind-oral-rinses.
Joeobiso. Nitric oxide in promoting healthy autonomic function - autonomic dysfunction treatment. Franklin Cardiovascular Associates, PA. https://franklincardiovascular.com/nitric-oxide-in-promoting-healthy-autonomic-function/.
Kumar S, Singh RK, Bhardwaj TR. Therapeutic role of nitric oxide as emerging molecule. Biomedicine & Pharmacotherapy. 2017;85:182-201. doi:10.1016/j.biopha.2016.11.125
Lin S. Does mouthwash kill good bacteria? Dr, Steven Lin. February 8, 2024. https://www.drstevenlin.com/mouthwash-kills-good-bacteria/?utm_source=chatgpt.com.
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