Other common name(s): peppermint oil, mint, balm mint, brandy mint, green mint
Scientific/medical name(s): Mentha piperitae
Peppermint is a plant native to Europe and is now cultivated widely in the United States and Canada. The oil from the leaves and flowering tops of the plant is used in herbal remedies. Its main active ingredients are menthol and menthone.
Available scientific evidence does not support claims that peppermint oil is effective in treating side effects related to chemotherapy and radiation. However, there is some evidence that it may be effective in controlling nausea after surgery. Preliminary studies suggest that direct contact with peppermint oil may be helpful in reducing spasms in the esophagus and intestines during endoscopies and other procedures. There is mixed evidence that enteric-coated peppermint oil (supplements that are coated so that they are not absorbed by the body until they reach the small intestine) might be helpful in treating symptoms of irritable bowel syndrome, such as cramps. It is known to worsen acid reflux in some people. Strong vapors of menthol or peppermint can cause breathing problems for some people, especially infants.
How is it promoted for use?
Proponents claim peppermint oil improves digestion and relieves intestinal ailments such as gas, indigestion, cramps, diarrhea, and symptoms of irritable bowel syndrome and food poisoning. Some say it has a soothing effect and reduces anxiety.
Sprays and inhalants containing peppermint oil are promoted to relieve sore throats, toothaches, colds, coughs, laryngitis, bronchitis, nasal congestion, and inflammation of the mouth and throat. Another reported use of peppermint oil is to apply it to the forehead and temples to relieve tension headaches. Some claim that salves made from menthol (one of the major active ingredients in peppermint) ease muscle pain and soreness associated with injuries, arthritis, rheumatism, and neuralgia. Menthol vapors are also believed to relieve respiratory and sinus congestion.
Aromatherapists claim the scent of peppermint improves concentration, stimulates the mind and body, decreases inflammation, improves digestion, and relieves stomach pain (see Aromatherapy).
What does it involve?
Peppermint oil is the most frequently used form of the peppermint plant. The pure oil or a liquid extract containing the oil can be taken directly or swallowed in capsules. It is also made in enteric-coated capsules, which are designed to melt after they pass through the stomach. Peppermint is also available as a spray and inhalant for treating ailments of the throat, mouth, nose, sinuses, and lungs. The leaves are sometimes brewed as a tea.
Peppermint oil is on the Commission E (Germany's regulatory agency for herbs) list of approved herbs. Common dosages are 1 to 2 capsules 3 times a day for irritable bowel syndrome; 1 tablespoon of leaves in a cup of boiling water for tea, 2 or 3 times a day; 3 to 4 drops in hot water for inhalation; 1% to 5% essential oil for nasal ointments; and 5% to 20% essential oil for other ointments applied to the skin.
Many well-known commercial products also contain menthol in salve form, which is rubbed directly on the skin or has its vapors inhaled. Peppermint is often used to flavor toothpaste, mouthwash, cosmetics, chewing gum, candy, and pharmaceuticals.
What is the history behind it?
Peppermint may have been used as a digestive aid thousands of years ago in ancient Egypt. More recently, peppermint has been used as a folk remedy for vomiting, morning sickness, respiratory infections, and menstrual problems. Preparations containing menthol have a long history as a treatment for muscle soreness and pain, itching, sunburn, and to clear nasal congestion.
What is the evidence?
There are many anecdotal reports supporting the use of peppermint as a treatment for various digestive and breathing complaints. However, there is not enough scientific evidence available to conclude that peppermint lives up to all the claims made by proponents, especially its use as a treatment for stomach cancer or any other type of cancer.
Although available scientific evidence does not support claims that peppermint oil is effective in treating side effects related to chemotherapy and radiation therapy, it was found to be useful in controlling nausea after surgery. A randomized clinical trial in the UK found that patients who received peppermint oil before surgery had less nausea after surgery than those who did not.
In 2002, researchers discovered a nerve ending that responded to cold and to menthol. This may explain the cooling sensation from menthol, as well as its common use as an inhalant to reduce congestion in the nose. However, available studies do not yet show whether it actually “opens” the nose or improves breathing when a person has a cold.
There is debate about whether peppermint oil is effective in treating irritable bowel syndrome. Several randomized controlled trials suggest that enteric-coated peppermint may be helpful, but the studies have been small and have not followed the patients very long. Well-designed larger studies are needed to determine whether this holds true.
Some early evidence suggests that instilling peppermint oil into the colon during a barium enema (an x-ray test of the bowel) may reduce intestinal spasms and decrease the need for intravenous anti-spasm medications. A recent study suggests that taking peppermint oil by mouth can reduce intestinal spasms during barium enema examination. A Japanese study looked at introducing peppermint oil directly into the esophagus to reduce spasms in the muscle ring above the stomach during endoscopy. The researchers reported it worked more quickly than an injection of a standard antispasmodic medicine. However, more well-controlled studies are needed to make definite conclusions. These results need to be checked in larger clinical trials before being routinely recommended.
Studies that looked at applying peppermint oil to the forehead and temples to help tension headache suggested it might be useful in some people, but further studies are needed to determine whether this is truly helpful for tension headache.
Aromatherapy using peppermint oil for nausea after surgery showed it to be no more effective than isopropyl alcohol or a salt water placebo. A gauze pad containing the liquid was placed under the patient’s nose, and the patient was asked to breathe deeply through the nose and exhale through the mouth. Nausea scores were the same across the groups, and only 52% of patients required conventional medicines to control their nausea. Four out of five patients were satisfied with how their nausea was managed. In this case, the change in patients’ breathing may have helped more than the aroma being tested.
Are there any possible problems or complications?
This product is sold as a dietary supplement in the United States. Unlike companies that produce drugs (which must provide the FDA with results of detailed testing showing their product is safe and effective before the drug is approved for sale), the companies that make supplements do not have to show evidence of safety or health benefits to the FDA before selling their products. Supplement products without any reliable scientific evidence of health benefits may still be sold as long as the companies selling them do not claim the supplements can prevent, treat, or cure any specific disease. Some such products may not contain the amount of the herb or substance that is written on the label, and some may include other substances (contaminants). Though the FDA has written new rules to improve the quality of manufacturing processes for dietary supplements and the accurate listing of supplement ingredients, these rules do not take full effect until 2010. And, the new rules do not address the safety of supplement ingredients or their effects on health when proper manufacturing techniques are used.
Most such supplements have not been tested to find out if they interact with medicines, foods, or other herbs and supplements. Even though some reports of interactions and harmful effects may be published, full studies of interactions and effects are not often available. Because of these limitations, any information on ill effects and interactions below should be considered incomplete.
Peppermint is considered safe when taken by non-allergic people in normal doses. It can cause irritation when applied to the skin. Because peppermint may increase symptoms of acid reflux disease and hiatal hernia, people with these conditions are advised to avoid the herb. People with gall stones or liver damage should also use caution when using peppermint. Peppermint oil and menthol products should not be applied to the nose or face of an infant or small child since they could cause trouble breathing.
Rare cases of allergic rashes, hives, asthma, and other reactions have been reported in people who are sensitive to peppermint or its components.
Acid-reducing medicines may allow enteric-coated peppermint to be released before it leaves the stomach, which may reduce its effect on an irritable bowel. Peppermint oil may interact with other medicines as well, so it is helpful to talk with your doctor or pharmacist about all medicines and supplements that you are taking.
Menthone (which makes up around 20% of peppermint oil) was given to rats for 4 weeks by mouth. It affected kidney and liver function, and very high doses caused cyst-like spaces in the brainstem. In other animal studies, large doses have caused weakness, seizures, and brain damage.
Menthol is considered to be the most toxic component of peppermint oil. As little as 2 grams are thought to be fatal in some, although people have survived higher doses.
In work settings, those who handle menthol are cautioned that it can irritate the eyes. Eyes should be thoroughly flushed if contact occurs. For skin contact, wash with soap and water. Stomach upset with pain, vomiting, vertigo, drowsiness, and coma may result from ingestion, and death may occur due to lung failure.
Peppermint oil should not be taken by injection; a recent report describes the case of a young woman who had serious lung damage after intravenous injection of peppermint oil. She survived but required intensive care and the support of a breathing machine for 13 days. Taking any type of oil by injection can cause serious effects, including death.
Peppermint oils, when taken by mouth, can affect the way that other drugs are absorbed by the body and may interfere with antacids, medicines for high blood pressure, and others. Mint salves and creams can cause the ingredients in other creams and ointments to be absorbed more quickly. Other potential interactions between peppermint and other drugs and herbs should be considered. Some of these combinations may be dangerous. Always tell your doctor and pharmacist about any herbs you are taking. Relying on this type of treatment alone and avoiding or delaying conventional medical care for cancer may have serious health consequences.
More information from your American Cancer Society
The following information on complementary and alternative therapies may also be helpful to you. These materials may be found on our Web site (www.cancer.org) or ordered from our toll-free number (1-800-ACS-2345).
The ACS Operational Statement on Complementary and Alternative Methods of Cancer Management
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Note: This information may not cover all possible claims, uses, actions, precautions, side effects or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for consultation with your doctor, who is familiar with your medical situation.
Last Revised: 11/28/2008