Mouthwash has long been a staple in oral hygiene routines, but its effects on the oral microbiome—a community of beneficial and harmful microorganisms in the mouth—are not always straightforward. While mouthwash can kill bacteria that cause bad breath and gum disease, it can also disrupt the delicate balance of your oral microbiome, potentially leading to long-term oral and systemic health issues.

Here’s a closer look at how mouthwash impacts the oral microbiome and how to choose microbiome-friendly options.

How Mouthwash Affects the Oral Microbiome

1. Kills Both Good and Bad Bacteria

Most mouthwashes, especially those with alcohol or strong antiseptics like chlorhexidine, don’t discriminate between harmful bacteria (like those causing cavities or gum disease) and beneficial bacteria that support oral health.

• Beneficial bacteria play a key role in maintaining the oral ecosystem, preventing overgrowth of pathogens, and balancing the pH of the mouth.

• Removing these bacteria can leave your mouth vulnerable to imbalances and infections.

2. Reduces Microbial Diversity

A healthy microbiome relies on a diverse population of microbes. Overuse of mouthwash can decrease this diversity, which is linked to oral health problems like increased risk of cavities, gum disease, and even fungal infections like thrush.

3. Disrupts Nitric Oxide Production

Some oral bacteria are essential for converting dietary nitrates (from vegetables like spinach and beets) into nitric oxide, a molecule that supports cardiovascular health by relaxing blood vessels. Overusing antibacterial mouthwash can disrupt this process, potentially affecting blood pressure and heart health.

4. Alters pH Levels

Certain mouthwashes can make the oral environment more acidic, which favors harmful bacteria like Streptococcus mutans that contribute to tooth decay, while discouraging beneficial bacteria.

5. Increases the Risk of Dysbiosis

Dysbiosis occurs when harmful bacteria overtake the oral microbiome due to a loss of beneficial bacteria. This imbalance can lead to bad breath, gum disease, and systemic inflammation.

Signs Your Oral Microbiome May Be Affected by Mouthwash

• Chronic bad breath despite regular oral care

• Increased sensitivity in gums or teeth

• Recurring cavities or gum issues

• Dry mouth or a burning sensation after use

• Oral infections, such as thrush or ulcers

How to Choose Microbiome-Friendly Mouthwash

1. Avoid Alcohol-Based Mouthwashes

Alcohol can strip the mouth of moisture and beneficial bacteria, leading to dry mouth and imbalances.

2. Look for Natural Ingredients

Choose mouthwashes with ingredients like:

• Xylitol: A natural sugar alcohol that inhibits harmful bacteria without affecting beneficial bacteria.

• Essential oils: Mild antimicrobial agents like tea tree oil, clove, or eucalyptus can target harmful bacteria gently.

• Aloe vera: Soothing and non-disruptive to the microbiome.

3. Opt for Probiotic or Prebiotic Mouthwashes

• Probiotic mouthwashes: Contain beneficial bacteria like Streptococcus salivarius K12 or Lactobacillus reuteri, which can replenish and balance the microbiome.

• Prebiotic mouthwashes: Contain ingredients that nourish existing beneficial bacteria, promoting a healthier microbial balance.

4. Check pH Neutrality

Look for mouthwashes with a neutral or slightly alkaline pH to avoid creating an acidic environment that favors harmful bacteria.

Best Practices for Using Mouthwash Without Harming the Microbiome

1. Use Sparingly

Mouthwash should complement brushing and flossing, not replace them. Limit use to once a day or as recommended by your dentist.

2. Focus on Targeted Use

• Use therapeutic mouthwashes for specific conditions (e.g., gum disease, post-surgical care) only for the prescribed duration.

• Avoid long-term use of antiseptic mouthwashes without a clear reason.

3. Rinse with Natural Alternatives

Consider microbiome-friendly rinses, such as:

• Saltwater (mild antibacterial effect without disruption).

• Green tea (rich in antioxidants and supports oral health).

• Herbal rinses (e.g., chamomile, thyme, or sage).

4. Prioritize Overall Oral Hygiene

Brushing twice a day, flossing, and staying hydrated are more effective in maintaining oral health than relying on mouthwash alone.

A Balanced Approach to Oral Care

The goal of using mouthwash should not be to “sterilize” your mouth but to support a healthy balance of bacteria. By choosing microbiome-friendly options and using mouthwash responsibly, you can maintain fresh breath and protect against oral disease without harming the beneficial bacteria that keep your oral microbiome thriving.