Chinese Name : 薄荷
Latin Name : Herba Menthae
This herb is the aboveground portion of Mentha haplocalyx Briq. or M. x piperita of European origin and other species of the family Labiatae or Lamiaceae. It is grown mainly in the Jiangsu, Jiangxi, and Zhejiang provinces of China, and other parts of the world. Idaho, Wiscousin, and Oregon are the major producers of peppermint and spearmint, and their essential oils. The plant is collected in summer, dried, and cut into pieces for use unprocessed.
Peppermint is cultivated in home gardens and cooked with other vegetables to add flavor. Carminative, antispasmodic, astringent, and and sudorific are qualities ascribed to the plant. Traditionally, peppermint was used for fevers, colds, nervous disorders of children, nosebleeds, fluxes, insect bites, and diseases of the nose, teeth, and throat.
Peppermint is one of the most commonly used herbs for treating Wind-Heat-type colds and influenza at an early stage.
Use of Peppermint in TCM
Pungent in taste and cool, it acts on the lung and liver meridians
Effects, Medicinal Uses, and Combinations
- Disperses Wind-Heat exopathogens:
- For symptoms of fever, headaches, a slight aversion to cold with a little sweating, conjunctival congestion, sore throat, and red eyes due to Wind-Heat colds, peppermint is commonly used with schizonepeta, forsythia fruit, and lonicera, as in Yin Qiao San or Yin Qiao Jie Du Pian (R-46).
- For the common cold with a swollen and sore throat, peppermint is combined with chrysanthemum, arctium fruit, platycodon root, and schizonepeta.
- Relieves measles: for treating measles, German measles in the early stages, and pruritus, mentha is blended with forsythia fruit, cicada slough (chan yi), and arctium fruit.
- Invigorates stagnant Liver-Qi marked by chest pain and distending costal pain. Peppermint can also be used with white peony root, bupleurum root, and other herbs, as in Xiao Yao Wan (R-41).
In a decoction of 3 to 6 g. when making a decoction, avoid boiling the herb too long.
Peppermint should not be used by those who have an Exterior deficiency with excessive or spontaneous sweating.
Side Effects and Toxicity
Peppermint tea does not have any side effects even when consumed for a long period. Peppermint oil should not be applied to the noses of children as it may provoke glottic spasms and respiratory arrest. The ingestion of excessive peppermint oil has been associated with interstitial nephritis and acute renal failure. The estimated lethal dose of menthol for humans is about 2 to 9 g. No mutagenic or carcinogenic effects of peppermint oil have been reported.
The leaves and stems of the peppermint plant contain about 0.1 to 1.0 percent of volatile oil that is composed mainly of menthol (29 to 48 percent), and methyl acetate (3 to 10 percent), with smaller amounts of menthofuran and limonene. To date, eighty-five chemicals have been isolated from peppermint oil. Peppermint oil is a colorless to pale green liquid with a pungent odor and burning taste, and cool aftertaste. Menthol can be crystallized at low temperatures. Other ingredients present in peppermint oil include viridiflorol, pulegone,1,8- cineole, and pipperitone. Other constituents include flavonoids, phytol, tocopherols, carotenoids, betaine, choline, azulenes, rosmarinic acid, and tannin.
- Peppermint is a CNS stimulant when taken orally in small dose, and induces skin blood vessel dilation and sweating. It has sweating and antipyretic properties.
- Peppermint extracts have antiviral action against Newcastle disease, herpes simplex, vaccinia, Semliki Forest, and West Nile virus in egg and cell cultures.
- Peppermint oil has an antispasmodic action on the isolated segments of ileum of rabbits and cats.
- Menthol has analgesic, anti-inflammatory, antiallergenic, and expectorant properties.
- Menthol and/or menthone compounds act on the nerve endings of the sensory nerves, treat numbness, and relieve pain and itching.