Peppermint

Peppermint is a flowering plant that grows throughout Europe and North America. Peppermint is widely cultivated for its fragrant oil. Peppermint oil has been used historically for numerous health conditions, including common cold symptoms, cramps, headache, indigestion, joint pain, and nausea. Peppermint leaf has been used for stomach/intestinal disorders and for gallbladder disease.

Mint plants such as peppermint and spearmint have a long history of medicinal use, dating to ancient Egypt, Greece, and Rome. The scientific name for peppermint ( Mentha x piperita ) is derived from the name Mintha , a Greek mythological nymph who transformed herself into the plant, and from the Latin piper meaning "pepper." Peppermint is believed to be a cross (hybrid) between spearmint and water mint.

Peppermint oil is available in bulk herb oil, enteric-coated capsules, soft gelatin capsules, and in liquid form. In small doses such as in tea or chewing gum, peppermint is generally believed to be safe in healthy, non-pregnant, non-allergic adults. The United States is a principal producer of peppermint, and the largest markets for peppermint oil are manufacturers of chewing gum, toothpaste, mouthwash, and pharmaceuticals.

Synonyms

Balm mint, black peppermint, brandy mint, curled mint, Feullis de menthe, Japanese peppermint, Katzenkraut (German), lamb mint, Mentha arvensis L. var piperascens, menta prima (Italian), Menthae piperitae aetheroleum (peppermint oil), Menthae piperita var officinalis, Menthae piperitae folium (peppermint leaf), Menthe anglaise , Menthe poivre , Menthe poivree , Mentha piperita var vulgaris, Our Lady's mint, pebermynte (Danish), peppermint oil, Pfefferminz (German), Porminzen, Schmecker, spearmint ( Mentha spicata L.), water mint ( Mentha aquatica ), white peppermint, WS(R) 1340.

Note: Mentha x villosa L. is a different species of mint with a similar appearance, used primarily as a flavoring agent.

Evidence

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Uses based on scientific evidence	Grade^*
Indigestion (non-ulcer dyspepsia) There is preliminary evidence that a combination of peppermint oil and caraway oil may be beneficial for dyspepsia (heartburn) symptoms. It should be noted that heartburn can actually be a side effect of taking oral peppermint oil. Patients with chronic heartburn should be evaluated by a qualified healthcare provider.	B
Irritable bowel syndrome (IBS) Peppermint may improveirritable bowel syndrome (ISB) symptoms. Additional study is necessary before a strong recommendation can be made.	B
Antispasmodic (colonic, esophageal, gastric spasm) Peppermint oil may be beneficial in reducing intestinal spasm during and after endoscopic procedures. However, more research is needed before a firm recommendation can be made.	C
Cough There is currently insufficient evidence available to determine the efficacy of peppermint oil in the management of cough.	C
Nasal congestion Menthol, a constituent of peppermint oil, is sometimes included in inhaled preparations for nasal congestion, including "rubs" that are applied to the skin and inhaled. High quality research is lacking in this area.	C
Nausea There is not enough evidence to recommend for or against the use of peppermint oil in the treatment of nausea. Further research is needed before a recommendation can be made.	C
Post herpetic neuralgia (herpes zoster pain) There is currently insufficient research available to determine if there are benefits of peppermint oil in the treatment of post-herpetic neuralgia.	C
Tension headache Application of diluted peppermint oil to the forehead and temples has been tested in people with headache. It is not clear if this is an effective treatment.	C
Urinary tract infection Peppermint tea added to other therapies has been used in the treatment of urinary tract infections. It is not clear if this is an effective treatment, and it is not recommended to rely on peppermint tea alone to treat this condition.	C
Vigilance improvement in brain injury (aromatherapy) There is currently a lack of sufficient evidence to recommend for or against the use of peppermint oil to affect vigilance following brain injuries.	C

*Key to grades
A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use;
F: Strong scientific evidence against this use.

Grading rationale

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Anorexia, antacid, antiviral, arthritis, asthma, bile duct disorders, bronchial spasm, cancer, chicken pox, cholelithiasis (gallstones), common cold, cramps, dysmenorrhea (menstrual pain), enteritis, fever, fibromyositis, gallbladder disorders, gas (flatulence), gastritis, gastrointestinal disorders, gonorrhea, head lice (Pediculus humanus capitus), ileus (post-operative), inflammation of oral mucosa, influenza, intestinal colic, laryngeal spasm, lice (Pediculus humanus capitus), liver disorders, local anesthetic, morning sickness, motility disorders, mouth and throat inflammation, mosquito repellant, mouthwash, musculoskeletal pain, myalgia (muscle pain), neuralgia (nerve pain), pruritis (itching), respiratory infections, rheumatic pain, sun block, tendonitis, toothache, tuberculosis, urticaria (hives), vomiting.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

Peppermint oil should be used cautiously, as doses of the constituent menthol over 1 gram per kilogram of body weight may be deadly. For intestinal/digestion disorders, doses of 0.2 to 0.4 milliliters of peppermint oil in enteric-coated capsules, dilute preparations, or suspensions taken three times daily by mouth have been used or studied. Lozenges containing 2 to 10 milligrams of peppermint oil have been used. 10% peppermint oil (in methanol) has been applied to the skin (forehead and temples) multiple times per day for headache relief. Some sources recommend using peppermint oil preparations on the skin no more than 3 to 4 times per day. For inhalation, 3 to 4 drops of oil added to 150 milliliters of hot water and inhaled up to three times per day or 1% to 5% essential oil as a nasal ointment has been used to relieve congestion.

As an infusion, 3 to 6 grams of peppermint leaf has been used daily. Doses of other liquid preparations depend on concentration, for example, 2 to 3 milliliters of tincture (1:5 in 45% ethanol) three times daily, or 1 milliliter of spirits (10% oil and 1% leaf extract, mixed with water) has been taken. Various doses of dried herb extract have also been used, ranging from 0.8 gram daily up to 4 grams taken three times daily, although safety is not clear.

Children (younger than 18 years)

There is not enough scientific information available to recommend the safe use of peppermint leaf or oil in children.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergic/hypersensitivity reactions may occur from using peppermint or menthol by mouth or on the skin, including throat closing (laryngeal spasm), breathing problems (bronchial constriction/asthma symptoms), or skin rash/hives/contact dermatitis. People with known allergy/hypersensitivity to peppermint leaf or oil should avoid peppermint products.

Side Effects and Warnings

Peppermint is generally regarded as being safe in non-allergic adults when taken in small doses, for example as tea.

Peppermint oil may be safe in small doses, although multiple adverse effects are possible. When used on the skin, peppermint oil has been associated with allergic/hypersensitivity reactions, skin rash/hives/contact dermatitis, mouth ulcers/sores, chemical burn and eye irritation. Lung injury has occurred following an injection of peppermint oil. Peppermint oil taken by mouth may cause headache, dizziness, heartburn, anal burning, slow heart rate, or muscle tremor. Very large doses of peppermint oil taken by mouth have resulted in muscle weakness, brain damage, and seizure.

Peppermint oil should be used cautiously by people with G6PD deficiency or gallbladder disease. Use in infants or children is not recommended due to potential toxicity.

Menthol, a constituent of peppermint oil that is included in mouthwashes, toothpastes, mentholated cigarettes, and decongestant "rubs" or lozenges, has been associated with multiple adverse effects, such as serious breathing difficulties, asthma, skin bruising (purpura), and mouth sores. Although small amounts may be safe in non-allergic adults, higher doses may be deadly in humans or cause brain damage. Use on the skin may also cause rash, severe skin damage (necrosis), or kidney damage (interstitial nephritis). Inhalation of large doses of menthol may lead to dizziness, confusion, muscle weakness, nausea, or double vision.

Pregnancy and Breastfeeding

Peppermint oil and menthol should be avoided during pregnancy and breastfeeding due to insufficient information and potential for toxicity.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs

Peppermint oil by mouth may increase blood levels of the drugs felodipine (Plendil®) and simvastatin (Zocor®). Peppermint oil increases levels of cyclosporine in the blood. Peppermint oil used on the skin with 5-fluorouracil (5-FU) may increase the rate of absorption of 5-FU.

Peppermint oil may interfere with the way the body processes certain drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be increased in the blood, and may cause increased effects or potentially serious adverse reactions. Patients using these medications should check the package insert and speak with a qualified healthcare provider including a pharmacist about possible interactions.

Peppermint may also interact with antacids, other calcium channel blockers or drugs that lower high blood pressure. Caution is advised.

Interactions with Herbs and Supplements

Peppermint oil may interfere with the way the body processes certain herbs or supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of other herbs or supplements to be too high in the blood. It may also alter the effects that other herbs or supplements possibly have on the P450 system. Patients using these medications should check the package insert and speak with a qualified healthcare provider including a pharmacist about possible interactions.

Peppermint (Mentha x piperita L.)

Background

Synonyms

Evidence

Dosing

Safety

Interactions