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What is Pennyroyal?

Both plants are members of the mint family and both are referred to as pennyroyal. H. pulegioides (American pennyroyal) grows in woods through most of the northern and eastern US and Canada while M. pulegium is found in parts of Europe. Pennyroyal is a perennial, creeping herb with small, lilac flowers at the stem ends. The leaves are grayish green and, like other mint family members, very aromatic.

Scientific Name(s)

Hedeoma pulegioides, Mentha pulegium

Common Name(s)

Pennyroyal also is known as American pennyroyal, squawmint, mosquito plant, and pudding grass.

What is it used for?

Traditional/Ethnobotanical uses

Pennyroyal has been recorded in history as far back as the first century AD, when it was mentioned by Roman naturalist Pliny and Greek physician Dioscorides. In the 17th century, English herbalist Nicholas Culpeper wrote about some uses for the plant including its role in women's ailments, venomous bites, and digestion. European settlers used the plant for respiratory ailments, mouth sores, and female disorders. The plant's oil has been used as a flea-killing bath, hence the name pulegioides (from the Latin word meaning flea), and has been used externally as a rubefacient (counter-irritant). In addition, the oil has found frequent use among natural health advocates as an abortive and as a means of inducing delayed menses. The oil and infusions of the leaves have been used in the treatment of weakness and stomach pains.

Miscellaneous uses

Pennyroyal has been used as an insect repellent, antiseptic, fragrance, flavoring, as an emmenagogue (to stimulate menstrual flow), carminative, stimulant, antispasmodic and for bowel disorders, skin eruptions, and pneumonia. The abortive effect of the oil is thought to be caused by irritation of the uterus with subsequent uterine contraction. Its action is unpredictable and dangerous. The dose at which the herb induces abortion is close to lethal, and in some cases it is lethal. Pennyroyal is not considered safe for ingestion for any use.

What is the recommended dosage?

Pennyroyal usually is used as the volatile oil as an abortive. Because of severe toxicity at doses of 5 g, it should not be used.


No longer considered safe.


Documented adverse effects. Avoid use. Abortive, hepatotoxic (toxic to liver), and neurotoxic.


None well documented.

Side Effects

Pennyroyal may cause abdominal pain, nausea, vomiting, lethargy, increased blood pressure and increased pulse rate, and dermatitis. In tea form, small amounts have been used without reported side effects.


In large portions, pennyroyal can cause abortion, irreversible renal damage, severe liver damage and death. A small amount of oil can produce delirium, unconsciousness, shock, seizures and auditory and visual hallucinations.


1. Pennyroyal. Review of Natural Products. factsandcomparisons4.0 [online]. 2005. Available from Wolters Kluwer Health, Inc. Accessed April 19, 2007.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.