Pennyroyal oil (Mentha pulegium)
Despite serious safety concerns, pennyroyal is used for the common cold, pneumonia, fatigue, ending a pregnancy (abortion), and as an insect repellant.
In manufacturing, pennyroyal oil is used as a dog and cat flea repellent, and as a fragrance for detergents, perfumes, and soaps.
Origin of Pennyroyal Oil
Pennyroyal is a perennial herb that grows up to 50cm (20 in) tall with smooth roundish stalks and aromatic, gray-green oval leaves. Lilac flowers are produced in distinct whorls in late summer and autumn. The plant has a fibrous creeping root.
It is a herbal remedy of ancient repute, and was used to purify the blood, for digestive and menstrual problems and feverish colds. It also has a deserved reputation as an insect repellent.
It is indeed a wonder why such a poisonous plant or oil has been in use as a folk medicine from ancient times. Although it is also true that most of the medicines (particularly in homeopathy) are based on poisons collected from plants and animals. It is the accuracy in the number of doses, frequency of administration, and diagnosis of a disease that their use as a medicine depends upon.
Other Names: Mentha pulegium, commonly (European) pennyroyal, also called squaw mint, mosquito plant and pudding grass.
Extraction: Pennyroyal oil is extracted from the fresh herb or slightly dried herb by steam distillation.
Chemical composition: The main chemical components of pennyroyal oil are pulegone, menthone, iso-menthone and neomenthone.
Blends well with: citronella, geranium, lavandin, rosemary, and sage.
Uses for Pennyroyal Essential Oil
The health benefits of pennyroyal essential oil can be attributed to its properties as an antimicrobial, anti-bacterial, antirheumatic, antiarthritic, antiseptic, astringent, cordial, decongestant, depurative, digestive, emmenagogue, insecticide and stomachic substance.
Abortifacient: pennyroyal’s use as an emmenagogue and abortifacient is from ancient times. However, its action as an abortifacient was linked to its toxicity. The amount required for abortion also endangered the pregnant woman’s life.
Antimicrobial & Antibacterial: The antimicrobial and antibacterial properties of pennyroyal oil are the results of its toxicity. Even in trace quantities (mere parts per million) this poisonous oil is deadly to microscopic living beings (microbes). Even a few milliliters can cause death to a human. It kills microbes and bacteria and protects us from the infections caused by them. It also exhibits antifungal activity.
Antirheumatic & Antiarthritic: Being a depurative, it promotes the removal of toxins like uric acid from the body, thereby eliminating the biggest cause of rheumatism. Anesthetic effect on the nerves also helps withstand the pain of rheumatism and arthritis. Its cordial or warming effect heats up the affected area and gives a more comfortable feeling. Finally, its stimulating effect on blood circulation increases blood flow to important organ systems, bringing warmth to the affected places.
Antiseptic: Wounds and internal organs, particularly the urinary tract, urethra, kidneys, and uterus may become septic due to infection by the germs. The highly poisonous nature of the pennyroyal oil makes it an antiseptic since it kills the germs or bacteria that cause sepsis. However, this oil should be used in very mild doses, as it is highly poisonous and an irritant.
Astringent: Traditionally, this oil is used as a gum strengthener, which is probably due to its astringent properties. This makes the gums contract and tighten their grip on the teeth. The effects of its astringency can also be felt on other parts of the body since it induces muscle contraction, pulls up loose hanging skin, gives the face a lift, strengthens hair roots, and helps stop hemorrhaging by contracting the blood vessels.
Cordial: Due to its stimulating property, the essential oil of Penny Royal increases blood circulation, which in turn warms up the whole body, thus behaving as a cordial. This warming effect gives relief from feelings of cold that often result from a fever.
Decongestant: The toxicity of this oil makes it an antiviral and fights infections in the lungs. This also loosens the phlegm and catarrh deposition in the lungs and the respiratory tracts, as well as promoting their expectoration. This way, it behaves as a decongestant for the lungs and respiratory tracts.
Depurative: There are certain reports that say that this oil can be used as a depurative, that is, a blood purifier. Certain components of this oil may help neutralize the toxins in the blood. Since it promotes blood circulation, it also helps proper mixing of fresh oxygen with the blood. In this way, it can purify the blood and keep the organs and cells properly oxygenated. An animal study found that pennyroyal essential oil increased hemoglobin, white and red blood cells, but did not have any effect on other blood indices. The increase in white blood cells indicates that it can strengthen the immune system.
Digestive: In an animal study published in 2018, it was found that pennyroyal essential oil improved performance, organ weight, serum lipids and intestinal morphology. It increased nutrient absorption in the intestines. Pennyroyal is been in used in folk medicine to facilitate digestion. This property is also reportedly present in its essential oil and it promotes digestion by stimulating the secretion of digestive juices.
Emmenagogue: Pennyroyal essential oil is sometimes used in herbal medicine as an emmenagogue. It is believed to open blocked and delayed menstruation cycles. The resultant stimulation of certain hormones like estrogen and progesterone makes the cycle more regular. However, there is little scientific evidence to support this.
Insecticide: this oil is toxic to humans and to other animals, it is toxic to insects as well. It is a very efficient insect killer and is highly effective if used in fumigants, sprays, and vaporizers. Insects also try to stay away from this oil. This oil is highly praised and reputed as an insect repellant. An experiment undertaken to study the acaricidal effects of different herb essential oils found that the pennyroyal derivative was the most effective.
Stomachic: Used in extremely low doses, this oil can cure stomach problems and can settle the stomach. It cures infections in the stomach, helps maintain the acid-base balance in the stomach by stimulating secretion of acids and bile into the stomach, and soothes inflammation and irritation in the digestive tract.
Word of Caution
This oil is highly poisonous to humans and other animals. Ingestion in even small doses can cause death. It is a strong abortifacient as well, and should, therefore, be strictly avoided during pregnancy. It is not used in aromatherapy, as inhalation in small quantities can seriously damage the lungs, the respiratory tracts, and the liver. Utilized in extremely high dilutions to treat ailments topically is recommended only with the support of a certified Aromatherapist. Furthermore, although several medicinal properties of this oil have been discussed above, most of them are reported to have been in use traditionally and their authenticity is not guaranteed.
Side Effects & Safety
When taken by mouth: Pennyroyal oil is UNSAFE. It can cause serious liver and kidney damage, as well as nervous system damage. Other side effects include stomach pain, nausea, vomiting, burning of the throat, fever, confusion, restlessness, seizures, dizziness, vision and hearing problems, high blood pressure, lung failure, and death.
When applied to the skin: Pennyroyal oil is UNSAFE when applied to the skin undiluted. 0.05% maximum dilutions are recommended.
Special Precautions & Warnings:
Pregnancy and breast-feeding: It is UNSAFE to take pennyroyal by mouth or apply it to your skin when pregnant or breast-feeding. There is some evidence that pennyroyal oil can cause abortions by causing the uterus to contract. But the dose needed in order to cause an abortion could kill the mother or cause life-long kidney and liver damage.
Children: It is UNSAFE to give children pennyroyal by mouth. Infants have developed serious liver and nervous system injuries, or even death, after taking pennyroyal.
Kidney disease: The oil in pennyroyal can damage the kidney and make existing kidney disease worse.
Liver disease: The oil in pennyroyal can cause liver damage and might make existing liver disease worse.