Mentha pulegium.   European pennyroyal, Pudding Grass   Family Labiatae     
A common wild or garden plant, in Britain, France and Germany. American Pennyroyal is Hedeoma pulegrioides.
PART USED: Aerial parts
TASTE and ODOR: Mint like, though characteristic.
ACTIONS
GROUP: The circulatory system- Diaphoretics
1. Diaphoretic.[1,2,3]
2. Carminative.[1,2,3]
3. Emmenagogue-[1,2,3] principally used for delayed menses.
4. Antiseptic.
5. Spasmolytic.[1]
6. Stimulant.[3]
Topically- Refrigerant.[1] Antiseptic.[1] Insect repellent.[1]
INDICATIONS
1. Common cold.[1,3] Catarrh. Coughs. Bronchitis. Whooping cough. Pneumonia. Pleurisy. Tuberculosis.
2. Delayed menstruation.[1,3] Dysmenorrhea.
3. Flatulent dyspepsia.[1,2,3] Intestinal colic.[1,2,3]
4. Joint pain.  Gout.[3]
5. To prevent insect bites- the oil is an insect repellant- not to be used during pregnancy.[3]
Topically- Cutaneous eruptions.[3] Itching.[3] Formication (a sensation of insects creeping on the skin). Gout.
SPECIFIC INDICATIONS: Delayed menstruation owing to chill or nervous shock.[1]
CONTRAINDICATIONS: Pregnancy.[1] In effective doses it is abortifacent and toxic.[3]
COMBINATIONS
PREPARATIONS:   3X /day
Dried herb  1-4 g,[1] or by infusion[1] 1:20.
Fluid extract  1:1 in 45% alcohol 1-4 ml.[1] 0.5-5 ml.[3]
Pennyroyal oil (BPC1934)  0.05-0.2 ml.[3]
Spirit of Pulegium 0.6-1.2 ml.[3]

ORIGIN: Britain and Europe, a common garden plant.
DESCRIPTION: Prostrate or erect, the stems quadrangular and much branched, often purplish. Leaves; shortly stalked, oval or elliptical, 6-20 mm long, 0.5-10 mm in width, margin entire or crenate, pubescent. Flowers; numerous, pale purple-mauve, in whorled clusters commencing half way up the stem.
References
Inner Path can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.
Constituents
Research
In small doses and as an infusion it is used for delayed menses, however in larger doses it is abortifacient and toxic.[1]
References
Weiss, Rudolf Fritz Herbal Medicine Translated from the Sixth German Edition of Lehrbuch der Phytotherapie by A. R. Meuss. (1988) ISBN 0-906584-19-1 British Library Calaloguing in Publication Data Beaconsfield publishers Ltd, Beaconfield, England.

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.
Abstract
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.
PMID: 15770540 DOI: 10.1055/s-2005-837819 Planta Med. 2005 Mar;71(3):214-8. ncbi.nlm.nih.gov

Pennyroyal toxicity: measurement of toxic metabolite levels in two cases and review of the literature
I B Anderson, W H Mullen, J E Meeker, Khojasteh-BakhtSC, S Oishi, S D Nelson, P D Blanc
Abstract
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.
Ann Intern Med 1996 Apr 15;124(8):726-34. doi: 10.7326/0003-4819-124-8-199604150-00004. PMID: 8633832 DOI: 10.7326/0003-4819-124-8-199604150-00004 pubmed.ncbi.nlm.nih.gov

Pennyroyal oil toxicosis in a dog
M Sudekum 1, R H Poppenga, N Raju, W E Braselton Jr
Abstract
A dog was treated for fleas with the application of pennyroyal oil obtained by the owner at a health food store. Vomiting ensued within 2 hours, and despite emergency treatment, the dog died within 48 hours. At necropsy, pennyroyal oil was determined to be the cause of death.
J Am Vet Med Assoc 1992 Mar 15;200(6):817-8. PMID: 1568929 pubmed.ncbi.nlm.nih.gov

Reduction of inflammation and colon injury by a Pennyroyal phenolic extract in experimental inflammatory bowel disease in mice
João Rocha, Rosa Direito, Ana Lima, Joana Mota, Margarida Gonçalves, Maria Paula Duarte, João Solas, Bruno Felício Peniche, Adelaide Fernandes, Rui Pinto, Ricardo Boavida Ferreira, Bruno Sepodes, Maria-Eduardo Figueira
Abstract
Purpose: Little is known about the pharmacological effects of the phenolic compounds of Pennyroyal (Mentha pulegium). This Mediterranean aromatic plant, used as a gastronomic spice and as food preservative by the food industry has been studied mainly due to its essential oil antibacterial properties, composed primarily by monoterpenes. With this work, we aimed to evaluate the effects of a phenolic extract of pennyroyal in the impairment of inflammatory processes in Inflammatory Bowel Diseases (IBD) and in the potential inhibition of progression to colorectal cancer (CRC).
Methods: To that purpose, we evaluated the effect of pennyroyal extract administration in a model of TNBS-induced colitis in mice and further determined its effect on human colon carcinoma cell proliferation and invasion.
Results: The phenolic extract of pennyroyal exhibited antioxidant properties in in vitro assays and administration of the extract in a rat model of carrageenan-induced paw oedema led to significant anti-inflammatory effects. Further results evidenced a beneficial effect of the phenolic extract in the attenuation of experimental colitis and a potential antiproliferative effect on cultured colon cancer cells, effects not previously described, to our knowledge. A reduction in several markers of colon inflammation was observed following administration of the extract to colitis-induced mice, including functional and histological indicators. A successful inhibition of cancer cell invasion and proliferation was also observed in in vitro studies with HT-29 cells. Furthermore, the extract also led to a reduced expression of iNOS/COX-2 in the colon of colitis-induced mice, both being crucial mediators of intestinal inflammation.
Conclusions: Taking into consideration the central role of inflammation in the pathophysiology of CRC and the recognised connection between inflammatory events and cancer, these results enlighten the relevance of the phenolic constituents of pennyroyal as important pharmacological sources in the investigation of new treatment options for patients with inflammatory bowel diseases.
2019 Oct;118:109351. doi: 10.1016/j.biopha.2019.109351. Epub 2019 Aug 22. PMID: 31545244 DOI: 10.1016/j.biopha.2019.109351 pubmed.ncbi.nlm.nih.gov