Substances & Homeopatic Remedies

Mentha pulegium

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Medicinal virtues:

The herb, boiled and drank, provokes women's courses and expels the dead child and afterbirth. If taken in water and vinegar mingled together, it stays the disposition to vomit. Mingled with honey and salt, it voids phlegm out of the lungs and purges by stool. Applied to the nostrils with vinegar, it revives those who faint and swoon. The fresh herb bruised and put into vinegar, cleanses foul ulcers and takes away the marks of bruises and blows about the eyes and burns in the face, and the leprosy if drank, and also applied outwardly. It eases headache, pains in the chest and belly, and gnawing of the stomach. The decoction helps the jaundice and dropsy and clears the eyesight. One spoonful of the juice sweetened with sugar-candy is a cure for whooping cough.

Modern uses:

Like other members of the Mint family, Pennyroyal is an excellent remedy for flatulence and colicky pains in the abdomen. But its main use is for promoting menstruation and so it should not be used during pregnancy. It is stimulating and warming and is given to children with stomach and bowel upsets and also to ease feverish symptoms in measles and whooping cough. The herb is taken by infusion. Due to the presence of a rich volatile oil, the herb should never be boiled.

Planta Med. 2005 Mar;71(3):214-8.  
Inhibitory effects of the essential oil of Mentha pulegium on the isolated rat myometrium.
Soares PM, Assreuy AM, Souza EP, Lima RF, Silva TO, Fontenele SR, Criddle DN.
Laboratorio de Farmacologia dos Canais Ionicos-LAFACI, Departamento de Ciencias Fisiologicas, CCS, Universidade Estadual do Ceara, Fortaleza-CE, Brazil.

The effects of the essential oil of Mentha pulegium L. (EOMP), a plant commonly known as "pennyroyal" or "poejo" that is used in folk medicine as an abortifaceant, were assessed on the isolated rat myometrium. Myometrial strips were stimulated with 10 nM oxytocin or 10 microM PGF (2alpha). EOMP (10 - 300 microg/mL) concentration-dependently and reversibly inhibited the amplitude of oscillatory contractions, being approximately 3-fold more active against contractions stimulated by oxytocin than those by PGF (2alpha) (IC (50) values of 45.7 +/- 5.6 microg/mL and 160.9 +/- 5.9 microg/mL , respectively), although the maximal inhibitory effect occurred at the same concentration (300 microg/mL ) in both cases. This action was shared by pulegone (30 - 300 microM), the principal component of the essential oil (IC (50) values of 21.8 +/- 2.1 microg/mL and 12.7 +/- 4.6 microg/mL , respectively). Nifedipine (30 nM - 30 microM) also abolished agonist-stimulated contractions, and was approximately twice and 12 times as potent as EOMP in inhibiting oxytocin- and prostaglandin F (2alpha) (PGF (2alpha))-stimulated contractions, respectively. In conclusion, our results show that the essential oil of the abortifaceant plant Mentha pulegium exerts an inhibitory effect on the contractile activity of the isolated rat myometrium. This oil shares a common effect with the voltage-dependent calcium channel (VDCC) blocker nifedipine, although ostensibly acting via a different mechanism. It thus appears that EOMP and pulegone do not exert direct toxic effects on the myometrium per se that would cause abortion, and other possibilities such as systemic metabolism of plant constituents may rather underlie the abusive use of Mentha pulegium in popular medicine.

J Med Entomol. 2004 Jul;41(4):699-704.
Insecticidal activity of plant essential oils against Pediculus humanus capitis (Anoplura: Pediculidae).
Yang YC, Lee HS, Clark JM, Ahn YJ.
School of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea.

The insecticidal activity of 54 plant essential oils against female Pediculus humanus capitis De Geer was examined using direct contact and fumigation methods, and compared with the lethal activity of delta-phenothrin and pyrethrum, two commonly used pediculicides. In a filter paper contact bioassay with female P. humanus capitis, the pediculicidal activity was more pronounced in eucalyptus, marjoram, pennyroyal, and rosemary oils than in delta-phenothrin and pyrethrum on the basis of LT50 values at 0.0625 mg/cm2. At 0.125 mg/cm2, pediculicidal activity of cade, cardamone ceylon, clove bud, myrtle, rosewood, and sage oils was comparable with that of the test insecticides. In fumigation tests with female P. humanus capitis at 0.25 mg/cm2, eucalyptus, marjoram, pennyroyal, and rosemary oils were more effective in closed containers than in open ones, indicating that the effect of these oils was largely a result of action in the vapor phase. Neither delta-phenothrin nor pyrethrum exhibited fumigant toxicity. The essential oils described herein merit further study as potential control agents for P. humanus capitis.

Pediatrics. 1996 Nov;98(5):944-7.
Multiple organ failure after ingestion of pennyroyal oil from herbal tea in two infants.
Bakerink JA, Gospe SM Jr, Dimand RJ, Eldridge MW.
Department of Pediatrics, University of California, Davis Medical Center, Sacramento 96817, USA.

BACKGROUND: Hepatic and neurologic injury developed in two infants after ingestion of mint tea. Examination of the mint plants, from which the teas were brewed, indicated that they contained the toxic agent pennyroyal oil. METHODS: Sera from each infant were analyzed for the toxic constituents of pennyroyal oil, including pulegone and its metabolite menthofuran. RESULTS: Fulminant liver failure with cerebral edema and necrosis developed in the first infant, who died. This infant was positive only for menthofuran (10 ng/mL). In the other infant, who was positive for both pulegone (25 ng/mL) and menthofuran (41 ng/mL), hepatic dysfunction and a severe epileptic encephalopathy developed. CONCLUSION: Pennyroyal oil is a highly toxic agent that may cause both hepatic and neurologic injury if ingested. A potential source of pennyroyal oil is certain mint teas mistakenly used as home remedies to treat minor ailments and colic in infants. Physicians should consider pennyroyal oil poisoning as a possible cause of hepatic and neurologic injury in infants, particularly if the infants may have been given home-brewed mint teas.

Ann Intern Med. 1996 Apr 15;124(8):726-34.
Pennyroyal toxicity: measurement of toxic metabolite levels in two cases and review of the literature.
Anderson IB, Mullen WH, Meeker JE, Khojasteh-BakhtSC, Oishi S, Nelson SD, Blanc PD.
San Francisco Bay Area Regional Poison Control Center, San Francisco General Hospital, CA 94110, USA.

BACKGROUND: Pennyroyal is a widely available herb that has long been used as an abortifacient despite its potentially lethal hepatotoxic effects. However, quantitative data for pennyroyal constituents and their metabolites in humans have not been previously reported. OBJECTIVES: To quantify pennyroyal metabolites in human overdose, to correlate these findings with clinical variables, and to place these findings in the context of previously reported cases of pennyroyal toxicity. DESIGN: Clinical case series of pennyroyal ingestions; quantification of pennyroyal metabolites by gas chromatography and mass spectrometry; qualitative detection of protein-bound adducts of the metabolites of pennyroyal constituents in human liver by Western blot assay; and review of the literature based on a search of MEDLINE, Index Medicus, and the reference citations of all available publications. RESULTS: We report four cases of pennyroyal ingestion. One patient died, one received N-acetylcysteine, and two ingested minimally toxic amounts of pennyroyal and were not treated with N-acetylcysteine. In the fatal case, postmortem examination of a serum sample, which had been obtained 72 hours after the acute ingestion, identified 18 ng of pulegone per mL and 1 ng of menthofuran per mL. In a serum sample from the patient treated with N-acetylcysteine, which had been obtained 10 hours after ingestion, the menthofuran level was 40 ng/mL. Review of 18 previous case reports of pennyroyal ingestion documented moderate to severe toxicity in patients who had been exposed to at least 10 mL of pennyroyal oil. CONCLUSION: Pennyroyal continues to be an herbal toxin of public health importance. Data on human metabolites may provide new insights into the toxic mechanisms and treatment of pennyroyal poisoning, including the potential role of N-acetylcysteine. Better understanding of the toxicity of pennyroyal may also lead to stricter control of and more restricted access to the herb.