Peppermint essential oil in the concentrated form the trial actually used, a measured 100 microliters a day, not diffused into the air or steeped in tea.
Itineranttrader
Illustrative: a generic vial of peppermint essential oil, not the specific product or packaging used in the University of Lancashire trial.
Two Drops of Peppermint Oil a Day Dropped Blood Pressure 8.5 Points in a Small Registered Trial
Every so often a real trial lands on something so ordinary that I have to check the number twice. This is one of those. A registered, placebo controlled trial out of the University of Lancashire gave adults with mildly high blood pressure two drops of peppermint oil a day, and the systolic number moved by roughly what a starting dose of blood pressure medication does.
- A registered, placebo controlled trial in England gave 40 adults with mildly high blood pressure either peppermint oil or a peppermint flavored placebo for 20 days.
- Systolic blood pressure fell from 130 to 122 in the peppermint group, a drop of 8.5 points, while the placebo group stayed essentially flat at 131.
- The dose was 100 microliters a day, roughly two drops, taken as a capsule, not diffused or brewed as tea, which is how nearly all peppermint content treats it.
- This is one small, 40 person, 20 day trial that has never been replicated, and nobody should stop or adjust blood pressure medication because of it.
What the trial actually did
Researchers enrolled 40 adults with prehypertension or stage 1 hypertension and randomized them to 100 microliters a day of peppermint oil or a peppermint flavored placebo, a genuinely well chosen control since the flavor is the obvious way a participant might guess which group they are in. After 20 days, adjusted systolic blood pressure in the peppermint group had dropped 8.48 points, from 130.05 down to 121.97. The placebo group barely moved at all, 130.93 to 131.05, essentially flat. Compliance in the peppermint arm was 93.3 percent, and only one person dropped out and one reported a side effect, both in the peppermint group.
Peppermint oil group
Adjusted systolic blood pressure, start of trial to day 20. A drop of 8.48 mmHg.
Placebo group
The same measurement, the same 20 days, on a peppermint flavored placebo. Essentially flat.
40 adults with pre or stage 1 hypertension, University of Lancashire, a pre registered, placebo controlled, 20 day trial. 95 percent confidence interval on the adjusted difference: negative 14.24 to negative 2.73 mmHg.
Why the flat placebo line is the detail that sells it
What makes this result more credible to me than the headline number alone is that the placebo group did not move even slightly. Normally in a short trial like this, both arms drift down a little from regression to the mean and simple attention effects, so a flat placebo line is not what a weak or accidental result usually looks like. The trial was also pre registered before it started, which matters because it means the researchers committed to their measurement and analysis plan in advance rather than choosing a favorable one after seeing the data. None of that makes a 40 person trial large. It just makes this particular small trial more trustworthy than most.
Honest caveat
Forty people over 20 days is small and short, and the confidence range around the result is wide enough that the true effect could plausibly be a third of the headline number. No independent group has replicated this. Twenty days tells you nothing about whether the effect holds for months or years, which is the timescale blood pressure interventions actually need to be judged on. The population studied had only mild elevation, prehypertension or stage 1 hypertension, so nothing here applies to anyone with established, treated hypertension, and nobody should adjust medication based on a single small trial. Ingesting essential oils is not automatically safe either. Peppermint oil can worsen reflux and interacts with some medications, and undiluted essential oil is not the same thing as a culinary extract.
a flat placebo line is not what a weak or accidental result usually looks like
What this means for you
If your blood pressure runs a little high and you are looking for something cheap and low risk to try alongside whatever your doctor already has you doing, this is a genuinely interesting, well designed small trial rather than another wellness rumor, and that distinction is rare enough on this beat that I wanted to cover it properly. What it is not is a reason to skip or change medication, and it is not evidence that diffusing peppermint or drinking peppermint tea does anything at all, since neither delivers anything close to 100 microliters of the oil itself. If you want to try what this trial actually tested, that means an enteric coated peppermint oil capsule at a comparable dose, taken with the same caution you would give any concentrated essential oil, and with your doctor kept in the loop if you are already on blood pressure medication.
Primary sources
- Sinclair J, Sant B, Du X, et al. "Effects of peppermint (Mentha x piperita L.) oil on cardiometabolic outcomes in patients with pre and stage 1 hypertension: A placebo randomized controlled trial." PLOS One, published April 23, 2026.
- Trial registration NCT05561543, "Effects of Peppermint Oil in Mild moderate Hypertension," ClinicalTrials.gov.
Common questions
Should I stop my blood pressure medication and switch to peppermint oil?
No. This is one 40 person trial over 20 days in people with only mild blood pressure elevation, and nobody should adjust or stop a prescribed medication based on a single small trial. If you take blood pressure medication, talk to your doctor before adding anything, including a supplement with real evidence behind it.
Does drinking peppermint tea or diffusing peppermint oil do the same thing?
No, and this is one of the more useful facts in the whole story. The trial used 100 microliters a day of peppermint oil taken directly, roughly two drops. Tea and diffusers deliver a tiny, inconsistent fraction of that amount and were not what this trial tested, so there is no evidence either of those common ways of using peppermint affects blood pressure at all.
Is it safe to take peppermint oil like this?
Peppermint oil is not automatically risk free just because it is a common household item. It can worsen acid reflux and interacts with certain medications, and concentrated essential oil is not interchangeable with a culinary extract. The trial reported one adverse event and one dropout, both in the peppermint group, out of 40 participants. Anyone considering this should talk to a doctor first, particularly if they take other medications.
Stay Curious.
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