Does Mouthwash Cause High Blood Pressure? Root Causes

There is a real but specific link between certain mouthwashes and higher blood pressure, and it comes down to one ingredient: antibacterial agents that kill both harmful and helpful mouth bacteria. Research published in the journal Nitric Oxide found that people who used an over-the-counter mouthwash twice daily saw a measurable increase in systolic blood pressure after just one week. The root cause is not the alcohol or the flavoring — it is the disruption of your mouth’s natural bacteria that help produce a molecule called nitric oxide, which your body uses to regulate blood pressure.

How Does Mouthwash Affect Blood Pressure?

The connection between mouthwash and blood pressure is indirect but biologically well-supported. Your mouth contains bacteria that convert dietary nitrates — found in leafy greens and beets — into nitrite. When you swallow that nitrite, your body turns it into nitric oxide, a molecule that relaxes blood vessel walls and lowers blood pressure.

Antibacterial mouthwash does not discriminate. It kills the bacteria that make this conversion possible. When you use it twice a day, you reduce the population of these helpful bacteria. Over time, less nitric oxide is produced, and blood vessels stay slightly more constricted. The result is a small but measurable rise in blood pressure.

A 2019 study in Free Radical Biology and Medicine tracked healthy adults who used an antibacterial mouthwash twice daily. After one week, their average systolic blood pressure went up by 2 to 3.5 mmHg. That may not sound like much, but at the population level, a 2 mmHg increase in systolic pressure is linked to a 7% higher risk of dying from heart disease.

Does Mouthwash Cause High Blood Pressure in Everyone?

No. The effect depends on whether your mouthwash contains chlorhexidine or other strong antibacterial agents. Most prescription mouthwashes contain chlorhexidine, and many over-the-counter brands like Listerine contain essential oils with antibacterial properties. These are the ones linked to blood pressure changes.

People with existing high blood pressure or heart conditions may be more sensitive to this effect. Their blood vessels are already under strain, so even a small reduction in nitric oxide availability can push pressure higher. Healthy individuals with normal blood pressure may see no change at all, or a change so small it does not matter clinically.

Your diet also matters. If you eat few nitrate-rich vegetables — spinach, kale, beets, arugula — your body already has less raw material for nitric oxide production. Killing mouth bacteria in this case has a smaller effect because there is less nitrate to convert in the first place. People who eat a lot of these vegetables and use antibacterial mouthwash may see the largest blood pressure increase.

What Does the Research on Mouthwash and Blood Pressure Show?

Several studies have examined this question, and the findings are consistent. A 2019 study published in Nitric Oxide gave 26 healthy adults a placebo mouthwash or a chlorhexidine-based antibacterial mouthwash to use twice daily. After one week, the antibacterial group had a significant increase in systolic blood pressure. Their mouth bacteria populations that convert nitrate to nitrite dropped by over 90%.

Another study from the University of Plymouth in 2020 looked at people who already had high blood pressure. Those who used antibacterial mouthwash twice daily had a harder time controlling their pressure compared to those who did not. The researchers noted that the blood pressure difference was large enough to matter in clinical care.

Not all mouthwashes are the same. Alcohol-based mouthwashes without strong antibacterial claims have not been linked to blood pressure changes in the same way. The key ingredient is the antibacterial agent — not the alcohol, not the color, not the flavor.

What Ingredients in Mouthwash Should You Watch For?

The ingredient most clearly linked to blood pressure changes is chlorhexidine. This is a prescription-only antibacterial agent used for gum disease and before dental surgeries. It is highly effective at killing bacteria, and that is exactly the problem. It kills the good bacteria along with the bad.

Over-the-counter mouthwashes often contain essential oils like eucalyptol, menthol, thymol, and methyl salicylate. These also have antibacterial properties, though they are less potent than chlorhexidine. The research on these is less clear, but some studies suggest they can still reduce helpful mouth bacteria with regular use.

Ingredients that do not appear to affect blood pressure include fluoride, cetylpyridinium chloride (in small amounts), xylitol, and zinc. These ingredients target cavity prevention or breath freshening without broadly killing oral bacteria. If you want to keep your mouth clean without risking a blood pressure change, these are safer choices.

• Chlorhexidine — strongest link to blood pressure increase. Prescription only.
• Essential oils — moderate antibacterial effect. Possible blood pressure link.
• Alcohol — not directly linked to blood pressure changes in research.
• Fluoride — no known effect on blood pressure.
• Xylitol — no known effect on blood pressure.
• Cetylpyridinium chloride — low-dose versions are likely safe.

What to Do If You Use Mouthwash and Have High Blood Pressure

If you have high blood pressure and use an antibacterial mouthwash twice daily, the most practical step is to switch to a non-antibacterial alternative. Fluoride mouthwashes and those with xylitol clean your mouth without killing the bacteria that produce nitric oxide. Your blood pressure may improve within a week or two after stopping the antibacterial rinse.

You can also change when you use mouthwash. Using it once a day instead of twice may reduce the impact on your oral bacteria. Some people choose to use mouthwash only before dental appointments or when they have an active gum infection, not as a daily habit.

Talk to your dentist if you are using a prescription chlorhexidine mouthwash. They may be able to prescribe a shorter course or recommend an alternative. For most people, brushing and flossing alone is enough for daily oral hygiene. Mouthwash is an extra step, not a necessary one.

Common Misconceptions About Mouthwash and Blood Pressure

A common myth is that alcohol in mouthwash causes high blood pressure. Alcohol consumed as a drink can raise blood pressure, but the small amount in mouthwash that you spit out does not enter your bloodstream enough to matter. The antibacterial effect is the real concern, not the alcohol content.

Another misconception is that any mouthwash is bad for blood pressure. This is not true. Only mouthwashes with strong antibacterial agents have been linked to blood pressure changes. Many brands are completely safe to use daily.

Some people also believe that the effect is too small to care about. For someone with normal blood pressure, that may be true. But for someone with borderline or high blood pressure, a 3 mmHg increase can be the difference between controlled and uncontrolled hypertension. The effect is real and dose-dependent — more frequent use means a larger impact.