Peppermint

Mentha x piperita L.

[Fam. Lamiaceae]

Overview

Peppermint is one of the most popular herbs for use in teas, flavorings, and confections (e.g., chewing gum and candies). Both peppermint leaf and peppermint oil are official in the U.S. National Formulary, while peppermint water and peppermint spirit have official monographs in the United States Pharmacopeia (USP, 2002). The U.S. is the world’s leading producer of peppermint oil (Fugmann et al., 1997), supplying more than 4,000 metric tons of oil annually (NASS/USDA, 2000). Three peppermint products are ranked in the top ten list of best selling single-herb teas (SPINS, 2000). Although most traditional uses of peppermint are based on teas used as a digestive aid, most clinical studies have investigated the actions of peppermint oil in enteric-coated capsules used internally to treat irritable bowel syndrome (IBS) and externally to treat tension headache.

Description

Peppermint leaf preparations consist of the fresh or dried leaf of Mentha x piperita L. [Fam. Lamiaceae]. The whole, dried leaf must contain not less than 1.2% (ml/g), and the cut leaf must contain not less than 0.9% volatile oil (Ph.Eur., 1997). Peppermint oil consists of the essential oil, obtained by steam-distilling freshly harvested, flowering sprigs (Blumenthal et al., 1998), and is neither partially, nor wholly dementholized (USP, 2002).

Primary Uses

Internal

Gastrointestinal

Crude Preparations

Indigestion and relief of bloating due to excess gas
production (Health Canada, 1996)

Spastic complaints of gastrointestinal tract, gallbladder, and bile ducts (Blumenthal et al., 1998; Braun et al., 1996)

Essential Oil

Non-ulcer or functional dyspepsia (Freise and Köhler, 1999; Madisch et al., 1999; May et al., 1996, 2000)

Irritable bowel syndrome (IBS) (Liu et al., 1997; Carling et al., 1989; Lawson et al., 1988; Nash et al., 1986; Dew et al., 1984; Rees et al., 1979; Pittler and Ernst, 1998)

External

Neurology

Essential Oil

Tension headaches (Göbel et al., 1994, 1996)

Other Potential Uses

Internal

Essential Oil

Catarrh of the respiratory tract and inflammation of the oral mucosa (Blumenthal et al., 1998)

Colonic spasm during barium enema (Sparks et al., 1995; Jarvis et al., 1992)

Colonic spasm during colonoscopy (Duthie, 1981; Leicester and Hunt, 1982)

Fecal odor in patients with colostomies (McKenzie and Gallacher, 1989)

External

Essential Oil

Myalgia and neuralgia (Blumenthal et al., 1998)

Dosage

Crude Preparations

Internal

Concentrated peppermint water (BP): 0.25–1.0 ml (BP, 1980; Karnick, 1994).

Dried leaf: 3–6 g (Blumenthal et al., 1998); 2–3 g, 3 times daily after meals for flatulent digestive pains (Bradley, 1992) 2–4 g, 3 times daily (Health Canada, 1996).

Infusion: Approximately 150 ml of boiled water poured over 1.5 g of dried leaf, steeped for 5–10 minutes in a covered vessel, tea bag squeezed over the cup, can be administered 2–5 times daily (Morant and Ruppanner, 2001; Braun et al., 1996; Hänsel et al., 1992–1994; Meyer-Buchtela, 1999), on an empty stomach to relieve upset stomach (Robbers and Tyler, 1999).

Note: Peppermint tea infusion yields ca. 21% of total available essential oil (Duband et al., 1992). At 10 minutes of steeping time, the maximum amount of volatile oil is obtained including ca. 24% of the menthol and 19.5% of the menthone (Hänsel et al., 1992–1994; Meyer-Buchtela, 1999). Steeping time limited to 5 minutes maximizes yield of menthol and menthone, as they volatilize rapidly (Niesel, 1992). After 5 minutes of steeping, 42–55% of the available rosmarinic acid is released, depending on the leaf particle size or surface area (Carius, 1990; Meyer-Buchtela, 1999).

Peppermint spirit USP: 20 drops (1 ml) with water (Robbers and Tyler, 1999).

Tincture [1:5 (g/ml), 45% ethanol]: 5–15 ml (Blumenthal et al., 1998; Erg.B.6, 1953); 2–3 ml, 3 times daily (Bradley, 1992; Health Canada, 1996).

Essential Oil

Internal

Essential oil: 6–12 drops total daily dose, according to German Commission E (Blumenthal et al., 1998) [Editors’ note: Caution: Peppermint oil is highly concentrated; therefore, divide into 3 doses and dilute in water or juice.]; 0.05–0.2 ml 3 times daily (Health Canada, 1996).

Essential oil in enteric-coated capsule: 0.2 ml oil (187 mg), 3 times daily with water before meals, for irritable colon (Morant and Ruppanner, 2001; Blumenthal et al., 1998; Krogh, 1989; Liu et al., 1997).

External

Essential oil: Drops rubbed in the affected skin areas, should be diluted with lukewarm water or vegetable oil (Blumenthal et al., 1998). 10 g in ethanol 90% solution, spread across forehead and temples. Repeated application after 15–30 minutes for tension headache (Göbel et al., 1996).

Inhalant: 3–4 drops of essential oil added to hot water and the steam vapor inhaled deeply (Blumenthal et al., 1998).

Nasal ointment: Semi-solid preparation containing 1–5% essential oil (Blumenthal et al., 1998).

Tincture: Aqueous-alcoholic preparation containing 5–10% essential oil for local application (Blumenthal et al., 1998).

Combination Preparations

Internal

Essential oil: 90 mg peppermint oil, 50 mg caraway oil, in enteric-coated capsule, 1 capsule 3 times daily, with water before meals, for non-ulcer dyspepsia (Freise and Köhler, 1999; Madisch et al., 1999).

Duration of Administration

The Health Canada labeling standard warns patients not to take peppermint internally for more than two weeks, or if symptoms recur when treating indigestion, unless directed by a healthcare provider (Health Canada, 1996). [Editors’ note: In Canada, all non-prescription drugs are given a duration use related to the indicated condition. This is based on the reasoning that the patient should be checked by a healthcare practitioner to look for underlying causes if the symptoms have not cleared up in the specified time.] The German Standard License monograph warns that for acute gastrointestinal complaints that last for more than one week or periodically recur, see a doctor (Braun et al., 1996).

Chemistry

Peppermint leaf contains up to 7% phenolic acids (caffeic, chlorogenic, and rosmarinic) (Bruneton, 1999); 3.5–4.5% labiate tannins; 0.5–4.0% terpene rich volatile oil, and flavonoids (glycosides of apigenin, diosmetin, and luteolin) (Hänsel et al., 1992–1994; Meyer-Buchtela, 1999). Peppermint oil (European pharmacopeial grade) must contain 30–55% menthol, 14–32% menthone, 2.8–10.0% menthyl acetate, 3.5–14.0% cineole, 1.5–10.0% isomenthone, 1–9% menthofuran, 1–5% limonene, and no more than 4% pulegone or 1% carvone (Ph.Eur., 1997).

Pharmacological Actions

Internal

Human

Crude Preparations: Antispasmodic action on the smooth muscles of the digestive tract, choleretic, carminative (Blumenthal et al., 1998; Bradley, 1992).

Essential oil: Antispasmodic, carminative, cholagogic, antibacterial, secretolytic/mucolytic (Blumenthal et al., 1998); relaxes smooth muscle (Micklefield et al., 2000); relieves colonic spasms (Leicester and Hunt, 1982); carminative on lower esophageal sphincter (Sigmund and McNally, 1969).

External

Human

Essential oil: Analgesic in tension headache (Göbel et al., 1994, 1996); menthol vapors stimulate cold receptors in nose (Burrow et al., 1983).

Internal

Animal

Peppermint tea increases bile secretion (Steinmetzer, 1926); peppermint oil applied locally suppresses free acid flow (Necheles and Meyer, 1935); peppermint oil shortens emptying time of stomach by 46% (Sapoznik et al., 1935); and inhibits serum cholinesterase (Caujolle et al., 1944); flavonoids are choleretic (Pasechnik, 1966; Pasechnik and Gella, 1966); aqueous extract acts as a sedative and diuretic (Della Loggia et al., 1990).

In vitro

Oil is bacteriostatic against Candida albicans, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa (Koscik, 1955); and bactericidal against Bacillus anthracis and swine erysipelas bacteria (Abdullin, 1962) and isolated human coli (Taylor et al., 1984b). Leaf extract is antiviral against Newcastle disease (NDV), herpes simplex, vaccinia, Semliki Forest, and West Nile viruses (Herrmann and Kucera, 1967); flavonoids inhibit ileum muscular contractions and relax gastrointestinal smooth muscle (Lallement-Guilbert and Bézanger-Beauquesne, 1970; Hill and Aaronson, 1991); alcoholic extract is anti-spasmodic (Forster et al., 1980; Forster, 1983); and inhibits colonic motility (Taylor et al., 1984a).

Mechanism of Action

The pharmacological actions are due partly to the volatile oil (Harries et al., 1978), to flavonoids and phenolic acids (Bruneton, 1999; Steinegger and Hänsel, 1988), and to the labiate tannins (Schilcher, 1997).

Some studies have proposed that the mechanism for the carminative action is peppermint’s ability to reduce the tonus of the esophageal sphincter, releasing entrapped air (Demling and Steger, 1969; Giachetti et al., 1988).

Based on in vitro experiments, the antispasmodic effect of the volatile oil is due to the inhibition of smooth muscle contractions through blocking calcium influx into muscle cells (Hawthorne et al., 1988; Hills and Aaronson, 1991; Taylor et al., 1984b).

Peppermint inhibits enterocyte glucose uptake by direct action at the brush border membrane. In serous membranes, it inhibits the response to acetylcholine without reducing the effect of mucosal glucose. This is consistent with a reduced availability of calcium, which causes a relaxing effect on the intestinal smooth muscle (Beesley et al., 1996).

After ingestion of an enteric-coated capsule, the menthol is not metabolized in the small or large intestine, but it reaches the colon. A third of the menthol is reabsorbed, and the rest acts locally on the smooth muscle. About 35% of the applied menthol is found in the urine after 24 hours (Morant and Ruppanner, 2001).

Contraindications

Crude herb: Gallstones (Blumenthal et al., 1998; Braun et al., 1996); esophageal reflux (Sigmund and McNally, 1969).

Essential oil: Achlorhydria (absence of free hydrochloric acid in gastric juice) (Morant and Ruppanner, 2001; Rees et al., 1979); obstruction of bile ducts, gallbladder inflammation, and severe liver damage. In case of gallstones, to be used only after consultation with a healthcare provider. Peppermint oil should not be used on the faces (particularly the noses) of infants and small children (Blumenthal et al., 1998). Peppermint oil is contraindicated for infants and small children due to the potential risk of spasms of the tongue or respiratory arrest (Schulz et al., 1998).

Pregnancy and Lactation: No known restrictions (Blumenthal et al., 1998; McGuffin et al., 1997).

Adverse Effects

None known according to Commission E (Blumenthal et al., 1998; Braun et al., 1996). Twelve cases of oral-contact sensitivity to peppermint oil and/or menthol have been reported in patients with intra-oral symptoms in association with burning-mouth syndrome, recurrent oral ulceration, or a lichenoid reaction (Morton et al., 1995).

Drug Interactions

None known (Braun et al., 1996; Blumenthal et al., 1998; ESCOP, 1997). Menthol-containing preparations may interfere with gastrointestinal-stimulant drugs (e.g., cisapride) used to treat nighttime heartburn due to the reflux of stomach acid into the esophagus (Austin et al., 2000). Concurrent administration of peppermint oil with antacids or ingestion during meals can cause the oil to be released from capsules prematurely resulting in a loss of effectiveness (Morant and Ruppanner, 2001).

American Herbal Products Association (AHPA) Safety Rating

Class 1: Herb that can be consumed safely when used appropriately (McGuffin et al., 1997).

Regulatory Status

Austria: Dried leaf official in Austrian Pharmacopoeia, ÖAB 1990–1996 (Meyer-Buchtela, 1999; Reynolds et al., 1993; Wichtl, 1997).

Belgium: Permitted as Traditional Herbal Medicine (THM) digestive aid (Bradley, 1992; WHO, 1998).

Canada: Peppermint Leaf Labeling Standard: Schedule OTC Traditional Herbal Medicine as an aid to digestion (Health Canada, 1996). Also permitted as a homeopathic drug. In both cases requires premarket authorization and assignment of a Drug Identification Number (DIN) (Health Canada, 2001). Food ingredient without claim (Health Canada, 1997).

European Union: Whole, dried leaf containing no less than 1.2% essential oil; cut, dried leaf containing not less than 0.9% essential oil; and steam-distilled oil from fresh, flowering, aerial parts are official in the European Pharmacopoeia (Ph.Eur., 1997).

France: Dried leaf official in French Pharmacopoeia, Ph.Fr. X (Bradley, 1992; Reynolds et al., 1993). Traditional Herbal Medicine for internal and external use with specific indications listed in the French Expl. Note, 1998. (Bradley, 1992; Bruneton, 1999; WHO, 1998). Oil is aromatherapy drug (Goetz, 1999).

Germany: Peppermint leaf and oil are approved drugs of the Commission E monographs (Blumenthal et al., 1998). Peppermint leaf tea is an approved drug in the German Standard License monographs (Braun et al., 1996).

Italy: Dried leaf official in Italian Pharmacopoeia (Reynolds et al., 1993).

Russian Federation: Dried leaf official in the State Pharmacopoeia of the Union of Soviet Socialist Republics, Ph.USSR X (Bradley, 1992; Reynolds et al., 1993).

Sweden: Classified as a natural remedy intended for self-medication, requiring premarketing authorization. A monograph for a peppermint-containing muliple-herb product, Uva-E tablet, is published in the Medical Products Agency (MPA) “Authorised Natural Remedies” (MPA, 1998, 2001; WHO, 1998).

Switzerland: Dried leaf official in Swiss Pharmacopoeia Ph.Helv.VII (Reynolds et al., 1993; Wichtl, 1997). Peppermint oil is a Category C nonprescription drug with sale limited to pharmacies. Peppermint tea is a Category D nonprescription drug with sale limited to pharmacies and drugstores (Morant and Ruppanner, 2001; WHO, 1998).

U.K.: Herbal medicine for oral use. General Sale List, Schedule 1, Table A (Bradley, 1992; Wichtl and Bisset, 1994). Peppermint leaf and oil official in the British Pharmacopoeia, BP 1993 (Health Canada, 1996).

U.S.: Generally Recognized as Safe (GRAS) (US FDA, 1998). Dietary supplement or conventional food depending on label claim statement (USC, 1994). Peppermint leaf and oil have official monographs in the National Formulary. Peppermint water and peppermint spirit have official monographs in the United States Pharmacopeia (USP, 2002).

Clinical Review

Twenty-three studies (1,185 total participants) are outlined in the following table, “Clinical Studies on Peppermint.” All but one of these studies (Nash, et al., 1986) demonstrated positive results for various gastrointestinal and neurological conditions. Included are 14 double-blind (DB) studies investigating treatment of non-ulcer or functional dyspepsia (Freise and Köhler, 1999; Madisch et al., 1999; May et al., 1996, 2000), IBS (Liu et al., 1997; Carling et al., 1989; Lawson et al., 1988; Nash et al., 1986; Dew et al., 1984; Rees et al., 1979); spasm during barium enema (Sparks et al., 1995); and tension headaches (Göbel et al., 1994, 1996). In 1998, a meta-analysis of DB, placebo-controlled trials indicated that peppermint oil could provide symptomatic relief of IBS, though the authors cited methodological flaws in most of the studies (Pittler and Ernst, 1998). In 2000, a systematic review of randomized, controlled trials concluded that peppermint oil for irritable bowel syndrome requires further study (Jailwala et al., 2000).

Branded Products*

Colpermin^®: Tillotts Pharma AG / Hauptstrasse 27 / CH–4417 Zeifen / Switzerland / Tel: +41–61–935–2626 / Fax: +41–61–935–2625. Enteric-coated capsules containing 187 mg (0.2 ml) peppermint leaf oil with 368 mg excipients per capsule, and E 132 coloring agent.

Enteroplant^®: Dr. Willmar Schwabe Pharmaceuticals / International Division / Willmar Schwabe Str. 4 / D-76227 Karlsruhe / Germany / Tel: +49-721-4005 ext. 294 / www.schwabepharma.com / Email: melville–eaves@schwabe.de. Enteric-coated capsules containing 90 mg peppermint leaf oil and 50 mg caraway seed oil.

Euminz^®: Lichtwer Pharma AG / Wallenroder Strasse 8-14 / 13435 Berlin / Germany / Tel: +49-30-40-3700 / Fax: +49-30-40-3704-49 / www.lichtwer.de. Liquid preparation containing 10 g of peppermint leaf oil and ethanol (90%).

Peppermint oil BP: Manufacturer information unavailable.

*American equivalents, if any, are found in the Product Table beginning on page 398.

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