Side effects of using too much mouthwash

Most dentists recommend using mouthwash occasionally as a supplement to diligent brushing and flossing. But some patients get in the habit of swishing aggressive rinses too frequently. This overuse comes with oral health drawbacks to consider.

Past studies have raised a red flag by identifying various ingredients in mouthwash that could lead to systemic adverse effects on our health.

For instance, a study from Harvard University found that using mouthwash more than once a day could be linked to diabetes or high blood sugar within three years. This is because of its antibacterial properties that get rid of both the helpful and harmful bacteria in your mouth, putting your oral health and general health at risk.

Mouthwash is a common part of many people’s daily oral hygiene routines. It promises to kill germs, freshen breath, and leave your mouth feeling clean and invigorated. However, behind these seemingly harmless benefits lies a potential danger that often goes unnoticed.

Let’s dive into this crucial topic to understand the risks associated with mouthwash.

A. Impact of mouthwash on blood pressure

A 2020 study observed that people who used over-the-counter mouthwash twice or more daily had an 85% higher risk of being diagnosed with hypertension compared to those who used it less frequently or not at all. This risk was also more than double that of individuals who did not use mouthwash.

The study observed that the potential impact of mouthwash on hypertension risk seemed to be higher among subgroups without certain hypertension risk factors, such as younger individuals, non-smokers, physically active people, non-alcohol users, and those who didn’t add salt to their meals.

However, stronger associations were noted among individuals with obesity, higher blood pressure levels, metabolic syndrome, insulin resistance, and moderate to severe periodontal (gum) disease.

That said, the study emphasizes that it cannot establish a causal relationship between mouthwash use and hypertension. However, the results align with findings from prior randomized controlled clinical trials, suggesting a potential connection.

How mouthwash affects blood pressure:

According to the researchers, one potential mechanism behind the association between mouthwash use and high blood pressure is the inhibition of nitrate reduction.

1. Nitrite reduction

Nitrate in the diet is converted to nitrite in the mouth, which plays a role in regulating blood pressure. Mouthwash, by disrupting this process, might contribute to blood pressure issues.

2. Long-term, frequent use

The study also observed that while mouthwash can have benefits when prescribed for specific conditions, over-the-counter mouthwash is often used long-term as part of routine oral hygiene. This long-term, frequent use is associated with an increased risk of hypertension, raising questions about its safety and long-term effects.

B. Identifying Potential Allergens in Mouthwash

Among the ingredients used in mouthwash, some have the potential to trigger allergic reactions. Researchers have pointed to a range of substances, including benzalkonium chloride, antibiotic agents, essential oils used for flavoring, alcohol, sodium perborate, zinc chloride, borax, methanol, thymol, phenol, iodine, methyl salicylate, and cresols.

These substances were identified as potential allergens that could cause adverse reactions in some individuals.

These allergic reactions can manifest in various ways, including oral discomfort, redness, itching, swelling, or even more systemic symptoms like hives or difficulty breathing.

If you suspect you have an allergy to any mouthwash ingredient or experience adverse effects, it’s advisable to discontinue use and consult a healthcare professional. They can help identify the specific allergen and recommend alternative oral hygiene products that are better suited to your needs and sensitivities.

Always read the ingredient label of mouthwash products, especially if you have a history of allergies or sensitivities.

Real-Life Cases

Instances of allergic reactions triggered by mouthwashes have been documented in medical literature, highlighting the seriousness of this issue.

1. Cinnamic Aldehyde-Containing Mouthwash:

Mathias and colleagues reported a case in which a woman with allergic rhinitis and asthma experienced lip swelling following the use of a mouthwash containing cinnamic aldehyde.

When the mouthwash was applied to the patient’s antecubital fossae (inner elbow) and the control subjects, immediate erythematous (redness) or urticarial (hives) responses occurred in all tested individuals.

This investigation confirmed cinnamic aldehyde as the culprit, with the reaction’s severity depending on factors like application site, concentration, and timing.

2. Proflavine and Benzydamine Mouthwashes:

Lim et al. reported cases of perioral and mucosal edema caused by contact allergy to proflavine in an acriflavine mouthwash. Additionally, a patient experienced a maculopapular rash on the trunk and limbs after using a benzydamine mouthwash.

C. Adverse Events Associated with Mouthwash

Studies have observed various side effects of using mouthwash, ranging from morphological (staining of the soft tissues in the mouth and dental-crown) to functional alterations (taste modifications and abnormal oral sensation):

Tooth Staining

Certain mouthwash ingredients like chlorhexidine and cetylpyridinium chloride may cause brownish tooth staining with prolonged, frequent use. These antimicrobial agents bind to surface pellicle over time. The discoloration is difficult to remove through regular cleaning.

Tissue Irritation

Common ingredients in many mouthwashes like alcohol and peroxide can irritate, dry out, and inflame oral tissues with repeated use, especially if swished vigorously. This may contribute to canker sores or bleeding gums.

Taste Alteration

Daily use beyond 2-4 weeks may impact taste sensation due to effects on taste bud receptors and saliva flow. This side effect called dysgeusia leads to reduced perception of sweetness, saltiness, bitterness, etc. It’s usually temporary but annoying.

Oral Cancer Risk

Studies show excessive use of alcohol-containing mouthwashes long-term may increase the risk of oral cancer. Alcohol dries the mucous membranes and allows penetration of other carcinogens. But this risk is still debated requiring further research.

Bad Breath Returns

If masking bad breath is the goal, dependence on mouthwash can backfire. Rinses only temporarily neutralize odor. It returns quickly if an underlying cause like gum disease or dry mouth isn’t addressed.

Bacterial Resistance

Frequent overuse of antibacterial rinses promotes selection of resistant bacteria strains in the oral microbiome. This may reduce positive effects over time and disrupt the normal flora balance.

Tooth Damage

If used improperly, swishing too vigorously can erode enamel over time. Acidic ingredients also weaken tooth structure with excessive exposure, increasing sensitivity and decay risk.

D. Finding the Right Balance

The key is using mouthwash rationally as a sometimes supplement, not a constant go-to. Follow these tips for the ideal mouthwash regimen:

  • Use no more than twice daily according to directions.
  • Select rinses without alcohol or hydrogen peroxide if prone to irritation.
  • Rinse thoroughly with water after to dilute and limit exposure.
  • Take periodic breaks from use to allow oral tissues to recover.
  • Have cleanings every 6 months for stain removal and to catch any developing issues.
  • Ask your dentist to recommend the best mouthwash and frequency for your needs. Customize use.

Final Thoughts

As you can see, mouthwash overuse has meaningful downsides, especially with certain active ingredients. There’s a reason products indicate use should be limited to two weeks or a certain number of rinses per day. Anything beyond moderate use risks outweighing benefits.

A little moderation and prudence goes a long way in harnessing mouthwash benefits without undesirable effects. Check ingredient lists and align usage with dental professional advice for happy, healthy smiles.



  • Editorial team

    A team comprising oral health care professionals, researchers, and professional Writers, striving to impart you with the knowledge to improve your oral health, and that of your loved ones. 

  • Lilly

    Lilly, aka, Liza Lee, is a passionate community oral health officer and our lead writer. She's not only well-versed in performing a multitude of dental procedures, including preventive, restorative, and cosmetic, but also an avid writer. Driven by the significant oral health burden all around her, Lilly strives to build capacity and promote oral health. She envisions making a lasting impact by advancing research, prevention, and promotion efforts to alleviate oral health disparities. Please share your views and opinions on my posts.

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