Peppermint is a relative of numerous wild mint plants, deliberately bred in the late 1600s in England to become the delightful tasting plant so well known today. It is widely used as a beverage tea and as a flavoring or scent in a wide variety of products.

Peppermint tea also has a long history of medicinal use, primarily as a digestive aid and for the symptomatic treatment of cough, colds, and fever. Peppermint oil is used for chest congestion (Vicks VapoRub), as a local anesthetic (Solarcaine, Ben-Gay), and most recently in the treatment of irritable bowel disease, also known as spastic colon.

What Is Peppermint Used for Today?

Peppermint oil has shown promise for a variety of conditions that involve spasm of the intestinal tract. Most studies have involved irritable bowel syndrome (IBS), for which peppermint oil has shown considerable promise. Peppermint oil may also be helpful for reducing the pain caused by medical examinations of the colon and stomach, as well for decreasing the intestinal gas pain that frequently follows surgery.

Peppermint oil may also be helpful for dyspepsia (a condition that is similar to IBS, but involves the stomach instead of the intestines).

Weak evidence, far too preliminary to rely upon at all, hints that peppermint oil might help dissolve gallstones.1

Peppermint oil is also used in another way: as aromatherapy. This means that it is inhaled, often by adding it to a humidifier. Weak evidence hints that inhaled peppermint oil might be helpful for relief of mucus congestion of the lungs and sinuses.21,22 Even weaker evidence hints that inhaled peppermint oil might relieve postsurgical nausea.2

Similarly weak evidence hints that peppermint oil, applied to the forehead, might relieve tension headaches.23,24

Finally, a study performed in Iran reported that applying peppermint water (essentially, lukewarm peppermint tea) directly to the nipples helped prevent dryness and cracking caused by breastfeeding.33

What Is the Scientific Evidence for Peppermint?

There have been numerous studies of peppermint oil for IBS.6-13,25,31,32,35,36. In one of the larger studies, 110 people with IBS were given either enteric-coated peppermint oil (187 mg) or placebo 3-4 times daily, 15 to 30 minutes before meals, for 4 weeks.8 The results showed significant improvements in abdominal pain, bloating, stool frequency, and flatulence. In a similar study, people who took peppermint oil capsules for 8 weeks also had less abdominal pain and discomfort compared to the placebo group.36

Not all of these studies have shown that peppermint oil is beneficial, though. It has been suggested that these inconsistencies were caused by the accidental inclusion of people who had conditions unrelated to IBS, but that cause similar symptoms. Presumably, peppermint oil may be less effective for these problems. A study published in 2007 pretested participants for lactose intolerance and celiac disease, the two conditions most easily mistaken for IBS.32 A total of 57 people with IBS symptoms and no evidence of the other two problems were enrolled in the study. Over a period of 4 weeks, participants were given either placebo or peppermint oil. At the end of the study period, 75% of the patients in the peppermint oil group showed a marked reduction of IBS symptoms (defined, for this purpose, as a reduction of IBS symptom scores by more than 50%). In comparison, only 38% of the participants given placebo showed an improvement of this magnitude, and this difference was statistically significant.

A barium enema involves introducing a solution containing the metal barium into the lower intestines. It commonly causes intestinal pain and spasm. A double-blind study of 141 individuals found that adding peppermint oil to the barium reduced the severity of intestinal spasm that occurred.14 Benefits were also seen in a large study conducted by different researchers.29

Another study found that peppermint oil reduced spasm in the stomach during a procedure called upper endoscopy.27

One study found that use of peppermint oil after C-section surgery reduced discomfort caused by intestinal gas.28

Peppermint oil is often used in combination with other essential oils to treat minor indigestion.

For example, a double-blind, placebo-controlled study including 39 individuals found that an enteric-coated peppermint-caraway oil combination taken 3 times daily for 4 weeks significantly reduced dyspepsia pain as compared to placebo.15 Of the treatment group, 63.2% was pain free after 4 weeks, compared to 25% of the placebo group.

Results from a double-blind, comparative study including 118 individuals suggest that the combination of peppermint and caraway oil is comparably effective to the no-longer-available drug cisapride.16 After 4 weeks, the herbal combination reduced dyspepsia pain by 69.7%, whereas the conventional treatment reduced pain by 70.2%.

A preparation of peppermint, caraway, fennel, and wormwood oils was compared to the drug metoclopramide in another double-blind study enrolling 60 individuals.17 After 7 days, 43.3% of the treatment group was pain free compared to 13.3% of the metoclopramide group.

Note: Metoclopramide works by reducing gastric emptying time (in other words, speeding the passage of food from the stomach into the intestines). Interestingly, some evidence suggests that peppermint oil may have the same effect.34

Dosage

The proper dosage of peppermint oil when treating irritable bowel syndrome is 0.2 ml to 0.4 ml three times a day of an enteric-coated capsule. The capsule has to be enteric-coated to prevent stomach distress.

When used in herbal combinations to treat stomach problems, peppermint oil is taken at lower doses, and it is not enteric-coated.

Safety Issues

At the normal dosage, enteric-coated peppermint oil is believed to be reasonably safe in healthy adults.18,19 However, case reports and one study in rats hint that peppermint might reduce male fertility.30 The species Mentha spicata may be more problematic in this regard than the more common Mentha piperita.

Excessive doses of peppermint oil can be toxic, causing kidney failure and even death. Very high intake of peppermint oil can also cause nausea, loss of appetite, heart problems, loss of balance, and other nervous system problems.

Safety in young children, pregnant or nursing women, or those with severe liver or kidney disease has not been established. In particular, peppermint can cause jaundice in newborn babies, so don't try to use it for colic.

Use of peppermint oil may increase levels of the drug cyclosporine in the body.26 If you are taking cyclosporine and wish to take peppermint oil, notify your physician in advance, so that your blood levels of cyclosporine can be monitored and your dose adjusted if necessary. Conversely, if you are already taking both peppermint oil and cyclosporine, do not stop taking the peppermint without informing your physician. When you stop peppermint, your cyclosporine levels may fall.

If you are taking:

  • Cyclosporine: Do not use peppermint oil (or stop using it) except in consultation with your physician.