Chlorhexidine is a broad-spectrum antiseptic used in prescription and over-the-counter mouthwashes. While effective against oral pathogens, it indiscriminately destroys the beneficial oral bacteria responsible for converting dietary nitrate into nitric oxide — a key regulator of blood pressure. Daily use has been shown in human trials to measurably raise blood pressure within one week.
Where it's found
Prescription mouthwash (Corsodyl), over-the-counter antiseptic mouthwash marketed for gum disease, dental rinses, some throat sprays, wound irrigation solutions in medical settings.
Routes of exposure
Oral absorption and mucosal contact from mouthwash use; ingestion of small amounts during rinsing.
Health concerns
Destroys nitrate-reducing oral bacteria (Veillonella, Actinomyces species) that convert dietary nitrate from vegetables to nitrite, which the body uses to produce nitric oxide. A 2019 clinical study (Tribble et al.) showed twice-daily chlorhexidine mouthwash raised systolic blood pressure by an average of 2.3 mmHg within one week — a clinically significant effect attributable to oral microbiome disruption. Regular use may also promote oral dysbiosis and antibiotic resistance.
Evidence
Tribble et al. (2019) Free Radical Biology and Medicine — randomised controlled trial in healthy volunteers showing blood pressure elevation after 1 week of twice-daily use. Nitric oxide suppression mechanism well established. The cardiovascular risk of long-term chlorhexidine use is not reflected in current prescribing guidance, which typically recommends short courses only for a reason — though this is not always communicated to patients.
Who's most at risk
People with hypertension or cardiovascular disease, patients on long-term mouthwash prescriptions, individuals with existing oral dysbiosis.
Regulatory status
RegulationUK MHRA: approved as OTC and prescription product; no restriction. EU: approved. Prescribing guidance typically recommends maximum 4-week courses — but this is rarely emphasised in consumer marketing.
How to reduce your exposure
Reserve chlorhexidine mouthwash for short-course use (maximum 4 weeks) as directed, not for daily long-term use. For routine oral hygiene, use fluoride toothpaste and an alcohol-free non-antiseptic mouthwash or salt water. Eating nitrate-rich vegetables (beetroot, rocket, spinach, celery) actively feeds the beneficial oral bacteria that chlorhexidine destroys.
The nutrition connection
This is one of Nutriofia's most compelling chemical-nutrition crossover stories: eating beetroot and leafy greens feeds the oral bacteria that produce nitric oxide, reducing blood pressure — and chlorhexidine mouthwash kills exactly those bacteria. The daily mouthwash habit can directly undermine the cardiovascular benefit of a nitrate-rich whole food diet. A perfect illustration that what you put in your mouth matters in every direction.