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The troubling swish and spit situation

Whether it’s right after waking up or after a meal chock full of garlic, everyone has had a time when they’ve felt they could use some mouthwash. 

While freshening your breath with mouthwash is a practice that dates back to the Romans, within the last 100 years mouthwashes have focused less on freshening your breath and more on killing the bacteria that cause it.

“Halitosis, or bad breath, is a condition caused by bacteria in your mouth,” said Jason Woloski, M.D., a Geisinger family physician. “The concept behind most popular mouthwashes is to kill the bacteria instead of masking the odor. While it’s effective for getting rid of bad breath, new studies are raising questions about the safety of repeated mouthwash usage—and even whether it could be linked to diabetes.”

Your mouth, the microbiome

Bacteria are responsible for a lot more than bad breath and getting you sick. In fact, you have an estimated 75 to 200 trillion different types of bacteria that live in and on your body—coexisting and helping you function. These bacteria and other microorganisms make up what is known as the human microbiome.

Some of these microorganisms are what cause plaque and bad breath. These organisms build up on the teeth, tongue and gums and can cause tooth decay and unpleasant odors. However, there are other bacteria that are essential to bodily functions.   

Killing bacteria a little too well
“The problem is that while there are bad and smelly bacteria we want to get rid of, there are good bacteria that we need,” said Dr. Woloski. “Unfortunately, mouthwash doesn’t differentiate and kills all bacteria. As a result, mouthwash can cause harm in the long run because it can disrupt the microbiome and impede the normal functioning of your body.” 

There is a similar concern with hand sanitizer, which can affect your immune system by killing all of the germs on your hands—even the ones that help your immune system stay strong.

In a recent study, researchers examined the link between developing diabetes and using mouthwash. They found that frequent mouthwash users (twice daily or more) were at a 55 percent higher risk of developing diabetes or having dangerous blood sugar spikes within three years.

The microbes and bacteria in your mouth form chemicals needed for your body to function. These chemicals play a role in regulating blood pressure, insulin sensitivity and other important functions, all of which are related to diabetes. Twice daily mouthwash use can decrease beneficial chemical levels by 90 percent—meaning these functions could be disrupted and lead to diabetes.
Is mouthwash the enemy?
The study cautions against the “indiscriminate routine use” of antibacterial mouthwash, with the highest risk among people who use it twice or more daily.

“Although the study suggests limiting your use of mouthwash, it does not indicate you should stop using it altogether,” said Dr. Woloski. “More research is needed to understand the link between mouthwash and diabetes, so diet and exercise are still the two most important components of diabetes prevention.”

Jason Woloski, M.D., is a primary care physician at Geisinger Kingston. To schedule an appointment with Dr. Woloski or another primary care physician, please call 570-283-2161 or visit
Man rinsing his mouth with mouthwash.