Table of Contents > Herbs & Supplements > American pennyroyal (Hedeoma pulegioides), European pennyroyal (Mentha pulegium) Print

American pennyroyal (Hedeoma pulegioides), European pennyroyal (Mentha pulegium)

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Also listed as: Hedeoma pulegioides L., Mentha pulegium L., Pennyroyal, Pulegone
Related terms
Background
Evidencetable
Tradition
Dosing
Safety
Interactions
Attribution
Bibliography

Related Terms
  • Aloe herbal horse spray, alpha-pinene, American false pennyroyal, American pennyroyal, beta-pinene, brotherwort, chasse-puces, churchwort, Cunila pulegioides, dictamne de Virginie, European pennyroyal, fleabane, flea mint, fretillet, Hedeoma phlebitides, hedeomal, herbal horsespray, herbe aux puces, herbe de Saint-Laurent, Iranian Mentha pulegium, Labiatae (family), la menthe pouliot (French), Lamiacae (family), lurk-in-the-ditch, Melissa pulegioides, mentha pouillot, menthone, Miracle Coat spray-on dog shampoo, mock pennyroyal, mosquito plant, Old World pennyroyal, paraffins, pennyroyal essential oil, petit baume, piliolerial, piperitenone, poley, pouliot royal, pudding herb, pudding grass, pulegium, pulegium oil, Pulegium vulgare, pulegone, pulioll-royall, Pulegium regium, run-by-the-ground, squaw balm, squaw mint, squawmint, stinking balm, tannins, terpenes (pulegone), tickweed.
  • Combination product example: PNC (contains pennyroyal, red raspberry, lobelia, blue cohosh, black cohosh, and blessed thistle).

Background
  • The essential oil of pennyroyal is considered toxic. Death has been reported after consumption of the extract and oil. A characteristic noted in most cases of pennyroyal overdose is a strong minty smell on the person's breath. Menthofuran, a toxic compound found in pennyroyal, can be detected in the urine, blood, or other tissues. Overdose management includes washing out the mouth and/or taking activated charcoal as an emergency treatment for poisoning.
  • Liver failure caused by pennyroyal is similar to liver failure caused by acetaminophen (Tylenol®). Since N-acetylcysteine (NAC) is used to treat liver failure caused by acetaminophen, it may also be used to treat liver failure caused by pennyroyal. More research is needed in this area.
  • Historically, the essential oil of pennyroyal has been used as an abortion inducer and menstrual flow stimulant. Yet, it may do so at lethal or near-lethal doses, making this action unpredictable and dangerous. Additional studies focusing on the less toxic parts of the pennyroyal plant and the menstrual cycle are needed before a conclusion can be reached.

Evidence Table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *


Traditionally, pennyroyal oil has been used to cause abortion. However, the use of pennyroyal is dangerous and illness and death have been reported.

C


Traditionally, pennyroyal oil has been used as a menstrual flow stimulant. However, the use of pennyroyal is dangerous and illness and death have been reported. Additional research is needed on the pennyroyal plant and the menstrual cycle.

C
* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)


Tradition / Theory

The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

  • Acne, antibiotic, antispasmodic (suppresses gut spasms), anxiety, asthma, cancer, carminative (relieves gas), colds/flu, cough, cramps, diaphoretic (promotes sweating), diarrhea, digestion, dizziness, fainting, fever, flavoring agent, fragrance (detergents, perfumes, soaps, potpourri), gallbladder disorders, gout, hallucinations, headache, hysterical affections (uncontrolled emotions manifesting as bodily disorders), improving urine flow, increasing lifespan, insect repellent, intestinal disorders, itchy eyes, joint problems, kidney disease, leprosy, liver disease, marks from bruises and burns, mouth sores, nosebleeds, pneumonia, pregnancy and labor, premenstrual syndrome, purifier (water, blood), respiratory problems, sedative, skin conditions (itching, burning), skin rejuvenator (improving skin smoothness), snake bites (venomous), stimulant, sunstroke, toothache, uterine fibroids (noncancerous growths in the uterine wall), whooping cough.

Dosing

Adults (18 years and older)

  • Note: There is no proven safe or effective dose for pennyroyal. The following doses have been used, but may be toxic.
  • In the form of a pennyroyal extract (1:2), weekly doses of 20-40 milliliters have been taken by mouth, but may be toxic.
  • In the form of an oil, doses of 0.5-3 drops have been taken by mouth, but may be toxic.
  • In the form of a tea/infusion, 1-2 cups of tea made from 1-2 teaspoons of dried leaves per cup of boiling water, steeped for 10-15 minutes have been taken by mouth daily, but may be toxic. For cough, congestion, and upset stomach, a tincture of 1.25-2.5 milliliters of pennyroyal in tea water has been taken by mouth up to twice daily, but may be toxic.
  • In the form of a tincture, doses of 30-60 drops have been taken by mouth twice daily or 1-2 milliliters have been taken by mouth three times daily, but may be toxic.
  • If an essential oil is to be used on the skin, it should first be mixed with another oil. The dilution ratio may vary. A 2 percent dilution is sometimes used when making whole body oil or lotions, and a 1 percent dilution is sometimes used for children and the elderly. However, safety and effectiveness are unproven, and skin preparations have been associated with side effects throughout the body.
  • For use as an insect repellent, crushed plant material and a pennyroyal tincture mixed with skin cream have been rubbed on the body, but may be toxic.

Children (under 18 years old)

  • There is no proven safe or effective dose for pennyroyal in children.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

  • Avoid in people with known allergy or sensitivity to pennyroyal, its parts, or its plant family. Allergic skin reactions and rashes have been reported.

Side Effects and Warnings

  • Note: If an essential oil is to be used on the skin, it should first be mixed with another oil. The dilution ratio may vary. A 2 percent dilution is sometimes used when making whole body oil or lotions, and a 1 percent dilution is sometimes used for children and the elderly. However, safety and effectiveness are unproven, and skin preparations have been associated with side effects throughout the body.
  • Pennyroyal is possibly safe when the flowers, leaves, and stems are mixed with other herbs and consumed as a tea taken by healthy adults for a short time. Pennyroyal is possibly safe when the flowers, leaves, and stems are used as an oil applied to the skin for a short time.
  • Pennyroyal herb and oils have been associated with toxicity and side effects. Cases of human overdose and death have been reported in infants, children, and adults. Typically, the first symptoms of poisoning, from either pennyroyal oil or leaves, occur in the stomach and bowels, and are often apparent soon after ingestion.
  • Use cautiously with all medicinal forms of pennyroyal and in people who have been using pennyroyal medicinally for longer than one week.
  • Avoid in children and pregnant or breastfeeding women.
  • Avoid in people with kidney disease.
  • Avoid in people with known allergy or sensitivity to pennyroyal, its parts, or its plant family.
  • Pennyroyal may cause abnormal clotting, abnormal heart rhythms, abortion, agitation, anemia, bad breath, bleeding, blood in the urine, brain damage, brain swelling, breast milk contamination, burning of the throat, changes in blood pressure, changes in heartbeat, changes in pupil size, chills, coma, confusion, death, decreased urine flow, diarrhea, dizziness, epilepsy, excess acid in the body, excessive sweating, fatigue, fever, hallucinations, hives, kidney problems, liver inflammation, loss of consciousness, lower blood sugar, lung damage, malaise (uneasiness), menstrual bleeding, nausea, nosebleeds, organ failure (brain, liver, lung, kidney, heart), psychosis, rashes, restlessness, retching, seizures, shock, skin discoloration, skin sensations, slow breathing, stiff muscles, stomach and intestinal abnormalities, stomach pains, urinary tract problems, vaginal bleeding, and vomiting.

Pregnancy and Breastfeeding

  • Avoid in pregnant and breastfeeding women due to the risk of abortion, stimulation of menstruation, transference through breast milk, and uterine contractions.
  • Many tinctures contain high levels of alcohol, and should be avoided during pregnancy.

Interactions

Interactions with Drugs

  • Pennyroyal may interfere with the way the body processes certain drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be increased in the blood, and may cause increased effects or potentially serious adverse reactions. People using any medications should check the package insert and speak with a healthcare provider or pharmacist about possible interactions.
  • Pennyroyal may lower blood sugar levels. Caution is advised when using medications that may also lower blood sugar. People taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare provider, including a pharmacist. Medication adjustments may be necessary.
  • Many tinctures contain high levels of alcohol, and may cause nausea or vomiting when taken with metronidazole (Flagyl®) or disulfiram (Antabuse®).
  • Pennyroyal may also interact with acetaminophen (Tylenol®), agents that are toxic to the liver, agents that increase seizure risk, agents that induce abortion, antiandrogens, antibiotics, anticancer agents, anti-estrogens, antihistamines, fertility agents, hormonal agents, and insect repellents.

Interactions with Herbs and Dietary Supplements

  • Pennyroyal may interfere with the way the body processes certain herbs or supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of these herbs or supplements may be altered in the blood, and may cause potentially serious adverse reactions. It may also alter the effects that other herbs or supplements possibly have on the P450 system.
  • Pennyroyal may lower blood sugar levels. Caution is advised when using herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.
  • Pennyroyal may also interact with antiandrogens, antibacterials, anticancer herbs and supplements, anti-estrogens, antioxidants, black cohosh, blue cohosh, herbs and supplements that are toxic to the liver, herbs and supplements that increase seizure risk, herbs and supplements that induce abortion, hormonal herbs and supplements, hormone replacement therapy (HRT), iron, licorice, N-acteylcysteine, and turmeric.

Attribution
  • This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography
  1. Anderson IB, Mullen WH, Meeker JE, et al. Pennyroyal toxicity: measurement of toxic metabolite levels in two cases and review of the literature. Ann Intern Med 4-15-1996;124(8):726-734.
  2. Anderson IB, Nelson SD, and Blanc PD. Pennyroyal metabolites in human poisoning. Ann Intern Med 1997;126(3):250-251.
  3. Bakerink JA, Gospe SM Jr, Dimand RJ, et al. Multiple organ failure after ingestion of pennyroyal oil from herbal tea in two infants. Pediatrics 1996;98(5):944-947.
  4. Black DR. Pregnancy unaffected by pennyroyal usage. J Am Osteopath.Assoc 1985;85(5):282.
  5. Buechel DW, Haverlah VC, and Gardner ME. Pennyroyal oil ingestion: report of a case. J Am Osteopath Assoc 1983;82(10):793-794.
  6. Carmichael PG. Pennyroyal metabolites in human poisoning. Ann Intern Med 2-1-1997;126(3):250-251.
  7. Ciganda C, and Laborde A. Herbal infusions used for induced abortion. J Toxicol.Clin.Toxicol 2003;41(3):235-239.
  8. Conway GA, Slocumb JC. Plants used as abortifacients and emmenagogues by Spanish New Mexicans. J Ethnopharmacol. 1979;1(3):241-261.
  9. Giorgi DF, Lobel D, Morasco R, et al. N-acetylcysteine for pennyroyal oil toxicity. Vet Human Toxicol 1994;36(4):358.
  10. Khojasteh-Bakht SC, Chen W, Koenigs LL, et al. Metabolism of (R)-(+)-pulegone and (R)-(+)-menthofuran by human liver cytochrome P-450s: evidence for formation of a furan epoxide. Drug Metab Dispos 1999;27(5):574-580.
  11. Mack RB. "Boldly they rode ... into the mouth of hell". Pennyroyal oil toxicity. N.C.Med J 1997;58(6):456-457.
  12. Martins HM, Martins ML, Dias MI, et al. Evaluation of microbiological quality of medicinal plants used in natural infusions. Int J Food Microbiol 8-15-2001;68(1-2):149-153.
  13. Mazur LJ, De Ybarrondo L, Miller J, et al. Use of alternative and complementary therapies for pediatric asthma. Tex.Med 2001;97(6):64-68.
  14. Perez-Calderon R, Gonzalo-Garijo A, Bartolome-Zavala B, et al. Occupational contact urticaria due to pennyroyal (Mentha pulegium). Contact Dermatitis 2007;57(4):285-286.
  15. Sullivan JB Jr, Rumack BH, Thomas H Jr, et al. Pennyroyal oil poisoning and hepatotoxicity. JAMA 12-28-1979;242(26):2873-2874.

Copyright © 2011 Natural Standard (www.naturalstandard.com)


The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.


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