A small randomised controlled trial testing peppermint oil blood pressure effects has found that twice-daily doses of the oil reduced systolic blood pressure by an average of 8.5 mmHg over 20 days in adults with mildly elevated readings, while a flavoured placebo produced little measurable change.
The trial, conducted at the University of Lancashire in Preston, enrolled 40 adults aged between 18 and 65 with prehypertension or stage 1 hypertension. Participants were randomly assigned to receive either 100 microliters of peppermint oil twice a day or a peppermint-flavoured placebo that contained none of the active oil. The results were published in PLOS One on 23 April 2026.
What the peppermint oil blood pressure study actually found
The primary outcome was systolic blood pressure, the upper figure in a standard reading. The peppermint oil group saw that figure fall by an average of 8.5 mmHg. The placebo group, by contrast, showed no meaningful change. The researchers also tracked diastolic blood pressure, heart rate, body measurements, blood test results, mental well-being, and sleep quality, though the study’s central focus was the systolic figure.
Peppermint naturally contains compounds including menthol and flavonoids, and the research team’s hypothesis was that those constituents might have a measurable effect on cardiovascular measures. The trial design, with a flavoured placebo, was intended to prevent participants from guessing which group they were in, a common methodological challenge when the test substance has a distinctive taste or smell.
Lead author Dr. Jonnie Sinclair, Reader in Sport and Health Sciences at the university, framed the findings in terms of the global burden of the condition: ‘High blood pressure is one of the biggest causes of heart disease and death worldwide, and it costs a huge amount of money to treat. Although medicines are commonly used to treat it, it’s not always clear how well they work in the long-term, and they can cause unwanted side effects.’
Dr. Sinclair added: ‘Our findings were very positive and they have significant clinical implications, especially given arterial hypertension is the most common preventable risk factor for cardiometabolic disease and the greatest single risk factor for global mortality. Peppermint oil is low in calories and price so it’s proved to be a very simple and cost-effective solution to potentially treat millions of people around the world.’
Funding and the limits of a 40-person trial
The trial was funded by the Dowager Countess Eleanor Peel Trust under grant reference MED1105. That funding context matters when reading the results: charitable medical research trusts often back exploratory, smaller-scale work that larger funders would not yet touch, and this trial is squarely in that category.
A sample of 40 participants is modest by clinical standards, and the 20-day duration tells us relatively little about whether the effect persists, fades, or is safe over longer periods. The researchers themselves describe the oil as a potential ‘additional option’ for managing mildly elevated blood pressure, not a replacement for established treatment pathways. The paper does not claim to have established a mechanism, only an association between the oil and a short-term reduction in one blood pressure measure.
None of that makes the result uninteresting. An 8.5 mmHg reduction in systolic pressure, if it held up in a larger and longer trial, would be clinically meaningful. The question the study cannot answer is whether it does hold up, whether the effect is specific to this dose and formulation, and whether any secondary outcomes shifted in ways the researchers did not foreground. What the PLOS One paper offers is a controlled signal worth following up, and the authors say that is precisely what they intend: they describe the oil as warranting further investigation as a low-cost, well-tolerated option for people in the early stages of elevated blood pressure.
