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Botanical Description & Habitat

Mentha piperita


Common names:
Amb mint
Brandy mint

Native to Great Britain and found in Europe and the United States. It prefers a moist soil and is generally found in damp places and marshes.

Has a creeping root which produces an erect, purple, hairy stem. It is branched near the top and reaches two feet in height. The leaves are opposite, petiolate, ovate, and dark green in color. Small, purple flowers grow in terminal spikes from July through September.

Medicinal parts
Leaves, dried, collected just before flowering.

Historical Properties & Uses

Peppermint, and to a lesser extent spearmint and cornmint, are among the most popular herbs; their many uses as flavoring ingredients are well known.

Medicinally, peppermint is used to aid the various processes of digestion: to combat gas, increase bile flow, heal the stomach and liver, etc. Its active constituents are found in its essential oil, mainly menthol and carvone. The oil's spasmolytic, anti-ulcer, anti-inflammatory, and antibacterial properties have been experimentally verified.

Peppermint is nontoxic, though some people may be allergic to the leaves.

Peppermint leaf and oil, as well as mint oil, are approved by the German Commisssion E for internal and external uses:

Mint and peppermint oil are used internally for flatulence, GI and gallbladder disorders and catarrh and externally for myalgia and neuralgia.

Peppermint leaf is used for spastic complaints of the GI tract and gallbladder.


Blumenthal, M (Ed.): The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. American Botanical Council. Austin, TX. 1998.

Method of Action

Peppermint is a common flavoring, which makes it seem familiar and therefore "simple". Actually, its chemistry is highly complex, with over 100 components, primarily menthol.

Peppermint is a digestive aid
Experiments conducted in Russia on four dogs with chronically implanted fistula of the gallbladder, indicated a preparation of peppermint leaves, containing mostly mixed flavanoids, had a pronounced choleretic effect on the liver, markedly increasing bile output. Its effect was superior to the choleretic drug chologon (ketocholamic acid). Bile composition was changed, resulting in decreased cholates, bilirubin, and cholesterol, although the total output of cholates increased.

Peppermint stimulates gallbladder contraction, resulting in increased digestion. A peppermint infusion or tea raises bile secretion to a level about 9 times greater than normal. In addition, the antiseptic property of peppermint helps disinfect the bile duct as it is secreted in the bile. A mode of action has been proposed for peppermint and a few other essential oils: they stimulate the vagus nerve, which then leads the secretion of bile.

Peppermint has spasmolytic properties
The spasmolytic property of peppermint has been established against many convulsant drugs, including acetylcholine, histamine, serotonin, and anaphylaxotocin. Preparations used include isolated cuts of rabbit and guinea-pig intestine, isolated guinea pig lungs, cat lungs "in situ," and whole animals under conditions of anaphylactic shock. The smooth muscle spasmolytic effect is myotropic, resembling that of papaverine. Peppermint extract has been found to decrease the tone of the lower esophagus sphincters to aid the escape of air.

Peppermint oils have strong antibacterial properties
Peppermint oils are consistently among the strongest antibiotic natural oils tested. In one study, for example, peppermint ranked among the top 3 of 17 essential oils tested for inhibition of swine erysipelas, and a sporeless culture of Bacillus anthracis. Of 22 essential oils tested in another study, peppermint was on of the top 5 inhibitors of 11 species of bacteria. In a semi-solid agar held at 45 degrees, peppermint and a select few other essential oils inhibited Streptococcus faecalis, Bacillus cereus, Salmonella enteritidis, and other gram positive and gram negative bacteria.

Candy made from peppermint and other such materials has a low content of microorganisms, due to the germicidal properties of its flavoring. Peppermint oil is effective against other organisms as well, including: Staphylococcus pyogenes, Streptococcus pyogenes, Penicillium glaucum, Aspergillus albus, Neisseria perflava, Sarcina lutea, Bacillus mensentericus, Bacillus subtilis, and Micrococcus aureus. Cornmint and spearmint also have effective antibacterial properties, as would be expected. Spearmint has some antitubercular and anthelmintic action.

Peppermint has considerable antiviral activity
Peppermint contains many of the same components as lemon balm, which had been shown to have considerable antiviral activity. On that basis, peppermint was investigated and found also to inhibit several viruses, including Newcastle Disease, Herpes simplex, vaccinia, Semliki Forest, and West Nile viruses in egg and cell-culture systems. The herb contains a tannin with an affinity for Newcastle virus and mumps virus, and a nontannin fraction with antiviral effects agains herpes simplex virus.

Azulene from peppermint has antipyretic and antiulcer actions
Azulene, an isolate from the residue of peppermint oil distillation has a marked antipyretic action. A 0.1 gm/kg dose, injected intramuscularly, was effective against hot water burns on the ear of a rabbit. Administered in a dose of 0.05 gm/kg, the preparation is effective in reducing pathological changes of the mucosa in experiments on rats with butadione-induced gastric ulcer. With intraperitoneal administration, the LD50 of azulen is 1.5 gm/kg for mice and 1.165 gm/kg for rats.

Mints have some cytotoxic properties
Cornmint and peppermint oils have some cytotoxic properties, but it is unlikely the whole plant would exhibit these effects.

Drug Interactions & Precautions

Possible Interactions
If peppermint is used on a daily basis, the following drugs may be imperfectly absorbed: tetracycline derivatives, oral anticholinergics, phenothiazines, digoxin, isoniazid, phenytoin, and warfarin.

The urinary excretion of alkaline drugs, such as amphetamines or quinidine, may be inhibited by the antacid nature of peppermint.

Peppermint's analgesic effects may be additive with other analgesics and anesthetics. These effects may be inhibited by barbiturates, despite any CNS-depressant effects which may occur. The analgesic property of this herb may be reversed or even eliminated by P-chlorophenylalanine, cyproheptadine HCl, and phenobarbital.

Conversely, the CNS-depressant tendency of this analgesic may be potentiated by chlorprothixene HCl, haloperidol, and tranquilizers.

Since peppermint's action depends on the presence of cholinergic substances, it will be affected by the decrease in cholinergic-receptor stimulation produced by anticholinergics.

The presence of azulenes in peppermint may interfere with the actions of bradykinin, histamine, acetylcholine, and serotonin.

In the absence of other hard data, it may be assumed observable interactions occur between the many central nervous system drugs and the psychoactive principles in this herb.

There is evidence to show combined use of bactericidal and bacteriostatic agents will lower the effectiveness of the bacteriostatic agent. However, how this finding applies to herbal anti-infectives is still unknown.

Safety Factors & Toxicity

Some individuals may experience allergic contact dermatitis from the plant, and some hay fever has been associated with fields of peppermint.

Menthol and menthol-containing drugs can be lethal to infants if applied to the nose, as when the infant has a cold. This use should be avoided.

Mint oil has approval status by the German Commission E.

Peppermint leaf has approval status by the German Commission E.


Blumenthal, M (Ed.): The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. American Botanical Council. Austin, TX. 1998.

Preparation & Administration

Three times a day

Dried herb
2-4 grams

made from 1 tsp of dried herb

0.05-0.2 ml (Use enteric coated capsules if for Irritable Bowel Syndrome)

This herb has approval status by the German Commission E.

Recommended daily dosages in Germany are as follows:


6 - 12 drops oil.
3 - 4 drops in hot water for inhalation.

3 - 6 g leaf
5 - 15 g leaf tincture


1 - 5% essential oil for nasal ointment
5 - 20% solution.


Blumenthal, M (Ed.): The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. American Botanical Council. Austin, TX. 1998.

Note: This Herbal Preparation information is a summary of data from books and articles by various authors. It is not intended to replace the advice or attention of health care professionals.



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Essential Oil

See Peppermint Essence under Aromatherapy