Common Antiseptic Mouthwash May Interfere With the Mouth's Role in Blood Pressure Regulation

Most people think of the mouth as the starting point of digestion, but a growing body of research suggests it also plays a direct role in cardiovascular health. The mechanism involves specific bacteria that live on the tongue and in the gum tissue. When you eat vegetables high in natural nitrates — such as leafy greens, celery, or beetroot — those bacteria convert the nitrate into nitrite. The body then uses nitrite to produce nitric oxide, a molecule that helps blood vessels relax and maintain healthy blood pressure.

A study from the University of Exeter, published in the journal Free Radical Biology and Medicine, is described by the researchers as the largest trial of its kind to examine this pathway. The trial recruited both younger adults and adults in their 60s and 70s. When older participants consumed a concentrated nitrate-rich beetroot juice shot twice daily for two weeks, their blood pressure measurably decreased — an effect that was not observed in the younger group. The researchers found that the blood pressure benefit was linked to changes in the composition of bacteria in the older participants' mouths, particularly the suppression of potentially harmful bacterial species.

A separate 2026 pilot study published in the journal Redox Experimental Medicine adds a complicating wrinkle for patients who use antiseptic rinses. That study found that chlorhexidine mouthwash — the active ingredient in many prescription-strength rinses — caused roughly a 78 percent drop in the oral bacteria responsible for nitrate conversion, and a dramatic reduction in nitric oxide production in the stomach. Dietary nitrate supplementation, the researchers found, partially preserved that microbial function even when chlorhexidine was being used.

The findings are early-stage and involve small study groups, so no firm clinical guidelines have changed. Researchers say larger studies are needed to understand how individual factors — including age, sex, medication use, and baseline oral bacteria — shape a person's response. Still, the research adds to a broader picture that the mouth's microbial environment may have measurable effects well beyond the teeth and gums, and that the choice of oral hygiene products is worth a conversation with your dental provider.