Mouthwashes reduce the blood-pressure-lowering effect of exercise
Exercise lowers blood pressure - that's well known. Blood pressure is higher during exercise, which is a completely normal regulatory response, but after exercise it usually falls below the level it was at before the physical activity. Over the long term, exercise also has a positive effect on blood pressure.
However, researchers in England found that an antiseptic mouthwash cancels out this effect.
Chlorhexidine inhibits bacteria in the mouth that convert nitrate into nitrite. Nitrite is a precursor of the vasodilator nitric oxide (NO). The researchers attribute the rise in blood pressure in the mouthwash group to this. The mouthwash reduced nitrite production in the mouth by 90 percent.
Another study supports this finding. In that study, 23 healthy adults exercised on a treadmill for 30 minutes and were then asked to rinse their mouths with mouthwash immediately afterwards and again after 60 and 90 minutes. However, some of the solutions provided contained only the control drink, while the others contained the mouthwash being tested. That way, the participants could not tell who received which sample. Blood pressure was measured in all participants before exercise and one and two hours after the workout.
The blood pressure of participants who rinsed with the control solution dropped as expected after exercise. On average, readings in this group were 5.2 mmHg lower than before. This level remained even two hours after the workout.
People who used the mouthwash after exercise only showed an average blood pressure drop of 2 mmHg, which had already disappeared by the final measurement after two hours.
This effect is due to the inhibited conversion of nitrate/nitrite into nitric oxide mentioned above. During exercise, more nitric oxide is produced to provide the muscles with sufficient oxygen; nitric oxide is known to widen blood vessels. According to the researchers, bacteria in the mouth that help convert nitrate to nitrite and then to nitric oxide play a key role in this. If these bacteria are prevented from doing their work by a chlorhexidine-containing mouthwash, the vessels cannot dilate sufficiently, and the post-exercise drop in blood pressure largely does not occur.
Because beetroot also works through this mechanism and can help lower blood pressure, it is possible that using a chlorhexidine-containing mouthwash after eating beetroot could cancel out that beneficial effect.
Sources
- https://www.sciencedirect.com/science/article/pii/S0891584912018229
- https://www.ncbi.nlm.nih.gov/pubmed/31369841
- https://www.medical-tribune.de/medizin-und-forschung/artikel/antiseptische-mundspuelung-kann-den-blutdruck-erhoehen/
- https://www.aerztezeitung.de/Medizin/Mundwasser-laesst-Blutdruck-steigen-251030.html
- https://www.iww.de/index.php/zr/allgemeine-zahnheilkunde/praevention-stickoxid-mehr-schaden-als-nutzen-durch-antibakterielle-mundspuelungen-f119629
- https://www.spektrum.de/news/mikrobiom-wie-sich-mundbakterien-auf-die-gesundheit-auswirken/1955962
This article is from Tensana – the leading app since 2011, helping hundreds of thousands of people monitor their blood pressure every day.
Our content is based on carefully researched, evidence-based data and is continuously updated (as of 01/2026).
Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as outpatient care, and has headed the specialist editorial team at Tensana since 2015. Thanks to her extensive additional qualifications as an emergency medical technician, first responder, and in various areas of therapy and emergency care, she provides well-founded, practical, and reliably verified information.
Author Sabine Croci is a qualified medical assistant with many years of experience in internal medicine and cardiology practices as well as outpatient care, and has headed the specialist editorial team at Tensana since 2015. Thanks to her extensive additional qualifications as an emergency medical technician, first responder, and in various areas of therapy and emergency care, she provides well-founded, practical, and reliably verified information.
