Peppermint

1. What Is Peppermint?

Peppermint is a cultivated mint species. It belongs to the family of the Lamiaceae. Mainly the leaves and the oil from the leaves are used. As tea and as oil it has long been used for digestive complaints. It is also applied externally.

2. Where Is It Found, and What Is It Made From?

Peppermint grows in temperate climates. It is cultivated in gardens and in fields. The leaves and the essential oil are used. The oil is obtained by steam distillation of the leaves. For tea, the leaves are dried.

3. What Does Peppermint Do? What Research Shows

Nausea

After operations, inhaled peppermint oil relieved nausea more than the control 263139. In breast cancer patients undergoing chemotherapy, ingested peppermint extract drops helped against nausea, vomiting and loss of appetite 24. The need for anti-nausea agents also decreased 2638. A review on inhalation found less nausea after operations, in pregnancy and after chemotherapy 9. In pregnant women, however, inhaled peppermint oil did not act better than a placebo 32. For tea or enteric-coated capsules, there is no separate controlled test here.

Irritable Bowel Syndrome

In irritable bowel, peppermint oil, mostly in enteric-coated capsules, improved overall complaints more than a placebo 23456. Abdominal pain also improved more 234. In children with functional abdominal pain, a peppermint oil capsule relieved duration, frequency and intensity of pain 18. In children with irritable bowel, however, peppermint oil was not more effective than a placebo 12. In adults, the primary goals were missed, some secondary measures improved 13. Mainly capsules were tested, not tea.

Cognition and Alertness

A controlled study with peppermint tea showed better scores in a computer test in healthy adults than with a placebo 34. A review on essential peppermint oil as a scent comes to no clear result 10. Overall, there are only a few small controlled studies. Tea and essential oil as a scent were tested. How the forms behave with longer use is open.

Headache and Migraine

The controlled trials concern migraine and chronic headaches in adolescents, not tension-type headache in the narrower sense. In adults with migraine, peppermint oil nasal drops relieved headaches more than a placebo and similarly to lidocaine drops 17. In adolescents with chronic headaches, a foot bath with peppermint oil did not help more than a foot bath without oil 33. The strength of evidence is low. How peppermint oil acts in tension-type headache is open.

Physical Performance

In recreational runners, essential peppermint oil in water prolonged running time to exhaustion compared with a placebo 35. In healthy participants, peak oxygen uptake and endurance time remained unchanged after several days of intake 36. The groups were small with 14 and 7 participants. The essential oil was tested, not tea, extract or enteric-coated capsules.

Functional Dyspepsia

In functional digestive complaints, peppermint was mostly tested in fixed mixtures with caraway oil or other medicinal plants. This effect cannot be attributed to peppermint alone. A controlled trial (with comparison group) with essential peppermint oil alone concerned ventilated intensive care patients and showed a reduced gastric residual volume 30. The effect of peppermint tea and of essential oil without caraway is open.

Respiratory Tract and Common Cold Symptoms

A controlled trial with nebulized essential peppermint oil in healthy participants showed no differences in lung values compared with eucalyptus oil, rosemary oil or no treatment 20. A small study without a control group reports improvements in lung values after mineral water with essential peppermint oil 42. However, this design does not allow causal attribution.

Other Investigations

Inhaled essential peppermint oil relieved pain more than the control, for example after joint replacement and disc surgery and during placement of a venous catheter 142528. Before injections at the dentist, children with peppermint oil on the mucosa felt less pain than with lidocaine gel or ice 15. In dialysis patients, peppermint gel reduced puncture pain, similar to a cold pack 23. In menstrual pain, peppermint capsules relieved pain similarly to mefenamic acid, but additional painkillers were taken more often 16. Anxiety also decreased more under inhaled peppermint oil than in the control group 1419282937. In cardiac patients who received a venous catheter, anxiety under peppermint scent did not decrease more than in the control group 25. In children before dental treatment, peppermint scent acted more weakly than chamomile and lavender 22. The robustness is high, but it is based predominantly on small, sometimes non-blinded studies with short follow-up.

4. How Was Peppermint Taken in the Studies?

The studies mainly tested inhaled or ingested essential peppermint oil, enteric-coated capsules and peppermint extract. Peppermint tea was tested in a controlled trial on cognition. Some studies investigated mixtures with other essential oils or plant extracts. Their results cannot be attributed to peppermint alone. Externally, peppermint oil was tested as a gel on the skin and on the oral mucosa 1523.

5. Is Peppermint Safe? Side Effects in the Studies

The side effects were mostly mild and temporary. The most common side effect was heartburn 4. Two reviews found more adverse events under peppermint oil 25, another no confirmed difference 3. In several controlled trials, peppermint oil was well tolerated, sometimes without differences to a sham 327. The evidence is overall broad, but many studies tested mixtures and small groups. Peppermint tea was not investigated in a controlled way in most areas.

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