A small randomized controlled trial found that 100 microliters of peppermint oil taken twice daily for 20 days reduced systolic blood pressure by approximately 8.5 mmHg more than placebo in people with pre- and stage 1 hypertension. The effect size was moderate to large, but the short duration and small sample size limit what we can conclude about real-world effectiveness.
This 20-day parallel randomized controlled trial enrolled 40 people with elevated blood pressure (pre-hypertension or stage 1 hypertension, defined as systolic BP between 120-159 mmHg) and assigned them to receive either peppermint oil or placebo twice daily. The peppermint group received 100 microliters per dose, while the placebo group received a peppermint-flavored inactive substance. Researchers measured blood pressure, heart rate, body composition, blood markers, psychological wellbeing, and sleep quality at baseline and after 20 days.
The primary finding was straightforward: systolic blood pressure dropped more in the peppermint group than the placebo group. At baseline, the peppermint group averaged 130.05 mmHg; by day 20, this had fallen to 121.97 mmHg, a reduction of about 8 mmHg. The placebo group started at 130.93 mmHg and ended at 131.05 mmHg, showing essentially no change. The adjusted difference between groups was 8.48 mmHg (95% confidence interval: -14.24 to -2.73) in favor of peppermint, with a moderate to large effect size (d = -0.94). Diastolic blood pressure and resting heart rate also improved numerically in the peppermint group, though the study was not powered to detect these as primary outcomes.
Secondary outcomes showed mixed results. No significant differences emerged between groups for anthropometric measures (weight, waist circumference), hematological markers (cholesterol, glucose, inflammation markers), or sleep efficacy. Psychological wellbeing measures favored the peppermint group slightly, though specific details were not detailed in the abstract. Adherence was excellent: 93.3% of participants in the peppermint group completed all doses, with only one dropout and one adverse event (both in the peppermint arm), suggesting the intervention was well-tolerated.
The mechanism behind peppermint's blood pressure effect remains unexplained by this study. Peppermint contains menthol and flavonoid compounds that may have vasodilatory properties, but this trial did not measure the mechanistic pathways. The finding is consistent with preliminary evidence suggesting dietary compounds with antioxidant and anti-inflammatory activity can modestly influence vascular function, though the specificity of this effect to peppermint oil versus other plant compounds remains unclear.
If you have pre- or stage 1 hypertension, this study suggests peppermint oil might offer a modest additional blood pressure reduction alongside standard approaches. An 8.5 mmHg systolic reduction is clinically meaningful, particularly when combined with other interventions. However, interpret this with appropriate caution: the trial lasted only 20 days, included just 40 people, and lacked a true control arm (the "placebo" was peppermint-flavored, which may not be inert if flavor itself influences blood pressure).
The practical question is durability. We do not know if this effect persists beyond 20 days, whether tolerance develops, or how peppermint oil interacts with blood pressure medications if you take them. We also lack data on optimal dosing, best formulation, or which populations benefit most. The study tested a specific dose (100 microliters twice daily), so using more or less peppermint oil may produce different results.
For those interested in exploring this, the intervention is inexpensive, well-tolerated, and appears unlikely to cause harm based on this small sample. It should be viewed as a complementary strategy, not a replacement for established approaches like regular aerobic exercise, sodium reduction, stress management, adequate sleep, and weight management if indicated. If you take antihypertensive medications, consult your healthcare provider before adding peppermint oil, as the combination has not been rigorously studied in this population.
| Parameter | Details |
|---|---|
| Study type | Parallel randomized placebo-controlled trial |
| Sample size | 40 participants (20 per arm) |
| Population | Adults with pre-hypertension or stage 1 hypertension |
| Intervention | 100 microliters peppermint oil, twice daily |
| Duration | 20 days |
| Primary outcome | Systolic blood pressure reduction |
| Main finding | 8.48 mmHg greater systolic BP reduction in peppermint vs placebo |
| Effect size | d = -0.94 (moderate to large) |
| Confidence interval | 95% CI: -14.24 to -2.73 mmHg |
| Adherence | 93.3% in peppermint group |
| Safety | 1 adverse event, 1 dropout (both peppermint arm) |
| Journal | PLOS ONE |
| Registration | NCT05561543 |
Katz B, 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. 2024. PubMed: 42024666
ProtocolEngine provides general health information based on published research. This is not medical advice. Consult a healthcare professional before starting any supplement or health protocol.