What is pennyroyal plant?

What You Need to Know About Pennyroyal

For 35 years, the writers and readers of Mother Earth News have shared hundreds of ways to use herbs to make life more enjoyable. In our archived articles, European and American pennyroyal (Mentha pulegium and Hedeoma pulegiodes) have been recommended as a way to deter fleas, as a vapor to relieve nasal congestion caused by colds, and as an infusion to cleanse the body of toxins.

We stand by using the pennyroyal plant to deter pests, but new information on the active ingredient in both species of pennyroyal, pulegone, merits a recall of taking pennyroyal into your body. In 1996, two California infants died after being given mint tea, in which the mint turned out to be pennyroyal. Most other pennyroyal incidents involve the use of pennyroyal essential oil (generally used for therapeutic or homeopathic purposes or as an insect repellent), which is so potent that it should be considered a poison. In the interest of safety, never use pennyroyal essential oil for anything, not ever.

Two thousand years ago, pennyroyal was the herb used to terminate unwanted pregnancies. Dr. Art Tucker, research professor at Delaware State University and author of The Big Book of Herbs , says that pennyroyal induces abortions by first damaging the mother’s liver. Death sometimes follows. In a well-documented case from 1994, a college student who drank only 2 teaspoons of pennyroyal oil in teas over a two-day period died from it. In 1992, a healthy dog died after licking a similar amount from its fur.

Obviously, there are good reasons to leave pennyroyal oil alone. However, the pennyroyal plant itself, as the most pungent member of the mint family, may have several good uses around your house.


As a flea deterrent . Dried pennyroyal leaves can be scattered around pets’ bedding area, and you can roll up some fresh stems in you dog’s bandana before you go tromping through the woods. Pennyroyal oil used in flea collars has largely been phased out because it caused miscarriages in cats, so only use the fresh leafy stuff, please. If a pet or person could be expecting, don’t use pennyroyal at all.

As a pest repellent. Crushed pennyroyal stems stuck in your hat and pockets really will repel gnats and mosquitoes. Dog owners often see their dogs rolling in pennyroyal patches, and dog instincts can usually be trusted.

In the garden. We’ve heard from folks who have successfully kept flea beetles off of eggplant by underplanting the eggplant with pennyroyal, and it may be of use as a companion plant to other pest-prone crops, too. If you have worked with pennyroyal as a companion crop, please share your experiences in the comments section below. Should you decide to try intercropping with pennyroyal, be aware that pennyroyal can be invasive, though it’s not as thuggish as other mints.

12 Best Benefits of Pennyroyal Essential Oil

The health benefits of pennyroyal essential oil can be attributed to its properties as an anti-microbial, anti-bacterial, anti-rheumatic, anti-arthritic, antiseptic, astringent, cordial, decongestant, depurative, digestive, emmenagogue, insecticide and stomachic substance.

What is Pennyroyal Essential Oil?

Pennyroyal essential oil is extracted form a plant belonging to the mint family. It is a grass-like creeper herb bearing the scientific name Mentha Pulegium. Its leaves smell like mint when crushed. The essential oil of pennyroyal is derived from the fresh plant by steam distillation and contains isomenthone, neomenthone, menthone and pulegone as its chief components. This oil is high in pulegone content and this makes it a deadly poison.

It is indeed a wonder why such a poisonous plant or oil has been in use as a folk medicine from ancient times. But again, 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.

Benefits of Penny Royal Essential Oil

Antimicrobial & Antibacterial

Research published in 2019 in the journal BioMed Research International found that the pennyroyal essential oil has strong antimicrobial properties.

The antimicrobial and antibacterial properties of pennyroyal oil are the results of its toxicity. You can imagine that even in trace quantities (mere parts per million) how deadly this poisonous oil might be for those tiny microscopic living beings (microbes) if it is so deadly for humans.

Even a few milliliters can cause death. It kills microbes and bacteria and protects us from the infections caused by them. It also exhibits antifungal activity.

Anti-Rheumatic & Anti-Arthritic

The depurative property, which is seen as the numbing effect of this oil on the nerves, as well as its cordial and stimulating effects on the blood circulation, make it an ideal combination as an anti-rheumatic and anti-arthritic treatment.

Being a depurative, it promotes the removal of toxins like uric acid from the body, thereby eradicating the biggest cause behind rheumatism. The numbing 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, while also curing them of rheumatism and arthritis.


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.


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 blood cells, 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.


In an animal study published in 2018 for the journal Heliyon, 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.


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.

It was also used as an abortifacient. Writing for the book Essential Oil Safety (Second Edition), writers Robert Tisserand and Rodney Young pointed out pennyroyal’s use as an emmenagogue and abortifacient 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, found the authors.


Since 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 very 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.


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.


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.


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.


Used in very 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 also soothes inflammation and irritation in the digestive tract.

Other Benefits

It is also used to treat flatulence, ailments pertaining to the gall bladder and liver, jaundice, hepatitis, and tumors.

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. 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.

There are no sufficient research studies or proof for or against these medicinal properties except its properties like toxicity, insect repelling, and abortifacient. So, the utmost care should be taken while using this oil, either internally or externally. So, before we use it for its medicinal properties, we must take serious precautions to see that it is only used under the supervision of an expert practitioner.

Blending: Penny Royal Essential Oil blends well with the essential oils of citronella, geranium, lavandin, rosemary, and sage.

Recently, I was reading one of my favorite blog sites when I came across this bit of advice. “The second best essential oil for repelling ticks is American Pennyroyal.” The writer went on to tell the reader to apply a few drops of oil to a dog’s fur.

I couldn’t believe what I was reading! I wanted to scream. Dogs not only lick their fur but also absorb 60% of what is applied to their skin. From an herbalist’s perspective, yes, pennyroyal is an effective insect repellent, but just because something works doesn’t mean it should be used.

Every herbalist has different teachers who have inspired them in their practice, a set of herbs that they favor, and a methodology that they utilize in their practice. No matter how we all differ, one element of herbalism that we can all agree on is the need for safety.

Does Natural Mean Safe?

Safety is one of the main reasons people are scrambling to find an effective natural alternative to pesticide laden pest control options. Many dog and cat owners are willing to try anything to avoid using these toxic chemicals. Knowing this, manufacturers have created a deluge of “natural” flea and tick products to address the growing concern. Thinking, “Well it is worth a try, anything is better than that toxic stuff I have been using,” people will try a product without researching the ingredients and sometimes without even reading the label.

Natural does not mean safe, and many misinformed owners are putting their dogs at greater risk by blindly entering the all-natural pet care world with unquestioning trust of the manufacturer.

The most popular pharmaceutical replacements for fleas and ticks are herbs and essential oils. All of these natural substances have within them the power to address a myriad of issues that our pets face every day. That being said, the use of many plants and their essential oils demands respect and knowledge. One such herb and essential oil that is a favorite of many makers of flea and tick protection is pennyroyal.

What is Pennyroyal?

Pennyroyal is also known as American pennyroyal (Hedeoma pulegiodes), European pennyroyal (Mentha pulegium) and Mountain pennyroyal (Mondardella odoratissima). It has been used as an insect repellent for centuries because insects absolutely detest its heady pungent odor. All species of pennyroyal belong to the Lamiaceae family and go by the common names of mosquito plant, tickweed, pudding grass, squamint, lurk-in-the-grass, and run-by-the-ground. Most people in the US just refer to it as pennyroyal, the smallest member of the mint family.

Toxic Effects

Considering it’s so small, pennyroyal really packs a punch. The main chemicals found in the plant’s essential oils include pulegone, methone, iso-menthone, octanol piperitenone, and trans-iso-pulegone. Of all these substances, pulegone is the most concentrated and threatening. Pulegone turns into the liver damaging chemical menthofuran when it enters the body. Pulegone is known as a keytone. Keytones are found in many essential oils and not all of them are dangerous. However, the keytones found in pennyroyal essential oil are deadly and make up over 85% of the chemical constituents in pennyroyal essential oil. This high percentage of harmful keytones makes it toxic to the kidneys, nervous system and the liver.

For example, a 1992 study (Sudekum M et al, Pennyroyal oil toxicosis in a dog, JAVMA.1992) reported that .07 oz of pennyroyal essential oil was applied to a dog’s skin to help control fleas. “Within 1 hour of application, the dog became listless and within 2 hours began vomiting. At 30 hours after exposure, the dog exhibited diarrhea, hemoptysis (coughing up blood) and epistaxis (bleeding from the nose). Soon thereafter, the dog developed seizures and died. Histopathiologic (tissue) examination of the liver showed massive hepatocellular necrosis”. In other words, the dog died of liver failure.

It is astonishing that the small dose of pennyroyal oil systemically shut down the dog’s organs. No matter what the veterinary staff tried to do to save the dog, they couldn’t. This example is very sad, but stands as a testament to the dangers of using pennyroyal essential oil for any reason.

According to Susan G. Wynn DVM who is certified in herbal medicine, the effects of pennyroyal toxicity may include the following:

  • Bloody Nose
  • Diarrhea
  • Nausea
  • Seizures
  • High blood pressure
  • Accelerated heart rate
  • Unconsciousness
  • Liver damage
  • Kidney damage
  • Renal damage
  • Abortion
  • Death

But It’s Such an Effective Repellent!

You may be asking yourself if there is any way that you can safely use pennyroyal on your dog since it is so effective at keeping insects away. My answer will always be no.

You will find many people who’ll tell you to roll up some of the herb in a bandana and put it around your dog’s neck before you go outside. This may be effective, but at what risk? Others will tell you that it is ok to sprinkle pennyroyal herb in and around your pet’s bedding to keep those pesky fleas away. Again, I would not recommend it.

If you are set on using pennyroyal no matter what the risks, then I would suggest using it as a tea or hydrosol (the water by-product of the essential oil distillation process) applied externally as a flea and tick dip or rinse. But again, my advice for using pennyroyal safely is not to use it at all!

There are safe, effective, natural flea and tick treatments on the market that don’t contain dangerous ingredients. I suggest that you research each ingredient on the label before purchasing and take great care in formulating your own insect repellent recipes.

As natural canine care expands and people come to depend on herbals as a viable alternative to pharmaceuticals, safety concerns expand as well. Good intentions: most people have them, but unfortunately when it comes to natural medicine, sometime even the best of intentions can result in some really bad advice.

Mentha pulegium (Pennyroyal Creeping) Herb Plant

Pennyroyal Creeping (Mentha pulegium) Herb in 9cm Pot

Creeping Pennyroyal is a member of the mint family, Lamiaceae, and crushed Pennyroyal leaves release a very strong fragrance similar to spearmint. Pennyroyal is a traditional culinary herb, folk remedy. Pennyroyal is the smallest of the Mints and very different in habit from any of the others. Creeping pennyroyal has quadrangular stems which grow to 10cm high, and as the name suggests, creeps along the ground, easily rooting at nodes if conditions are suitable. The small oval leaves are hairy on both sides, and greyish green in colour.

This really is a lovely little plant that is perfect for ground cover, plant this so it overflows onto a path and when crushed underfoot the scent is amazing. Of course, you could plant a whole lawn of this, should you wish. Semi-evergreen in habit, with small pale green leaves; atop this, pale lavender flowers appear in whorled clusters sporadically over the summer months. It can reach a height of approximately 9″ (23 cm) but can be kept trimmed and/or walked on or for ground cover.

This is also an excellent plant for areas where ants are troublesome as they hate the scent. Creeping Penny royal is also a great nectar source for bees and other beneficial insects.

Pennyroyal will tolerate sun or shade, but prefers a moist soil, may need protection from frost in exposed areas.

Herb Usage

An essential oil is obtained from the whole plant. Rats and mice intensely dislike the smell of mint. The plant was therefore used in homes as a strewing herb and has also been spread in granaries to keep the rodents off the grain. The leaves have a strong spearmint fragrance and can be used to make a herb tea. We recommend growing for its grond cover properties and not for consumption as it has a pretty bitter taste as well as being dangerous to pregnant women.


Buy Creeping Pennyroyal Online

Our potted Creeping Pennyroyal herb plants are generally available to buy online between March and September.

Pennyroyal Mint
Botanical Name: Mentha pulegium

Pennyroyal is a small, groundcover perennial with glossy green leaves. It reaches a height of only 15cm and has an indefinite width due to its spreading nature. The plant is able to spread on the ground’s surface as well as in the soil, rooting at nodes when vegetative parts of the plant touch the ground. This creeping habit means that Pennyroyal is an ideal groundcover, which is also highly aromatic. There is also Pennyroyal ‘Upright’ which reaches up to 30cm high. This variety is similar except for the plant structure and also spreads. However, it does not root easily at the nodes.

The tiny mauve flowers appear in late spring, held in whorled clusters. They grow up the stem in tiers, extending out from near the leaf nodes. The oval leaves are a dark glossy green colour, with small hairs on either side. They are held in opposite pairs on short stalks, averaging about 2.5 cm long and 1.5 cm wide. This small herb is native to Europe and some parts of Asia, but has been naturalised in many regions whenever it finds a suitable climate. It particularly likes to grow in moist ground near watercourses.

The common name Pennyroyal was derived from the word ‘Puliol’, the old French name for thyme. This became Royal Puliol, then Puliol Royale and finally developed into Pennyroyal. In France this plant is called La Mentha Puliol. The botanical name is Mentha pulegium, with Mentha indicating that this plant is categorised as a member of the Mint genus. The species name ‘pulegium’ is derived from the Latin ‘pulex’ which means flea. This refers to the traditional use of eradicating fleas by burning and smoking the leaves, or by using the fresh plant. The Romans knew this plant simply as Pulegium. Pennyroyal may also be called Creeping Pennyroyal, Squawmint, Mosquito Plant or Pudding Grass.

There are several cultivars which have been developed by gardeners over the years. Pennyroyal has a very different form to the other members. More information about other mints can be found below.

Mint General

There are many Mint varieties known to herb gardeners and lovers of good cuisine, all varying slightly in flavour, aroma and appearance. They are categorized in the genus ‘Mentha’, which has up to 18 species, within the Lamiaceae family of plants. The Lamiaceae family is known as the mint family. However, the largest group of plants in the mint family is actually the delightful Salvias with their brilliantly coloured blooms. Many other commonly known herbs are also found in this family, including basil, sage, thyme and even lavender. One characteristic of this plant family is that they all yield essential oils, giving each plant its unique characteristics and even potential for medicinal use. Even the Scutellaria genus, with the unusually named Baikal Skullcap is found within this family.

The mints consist of mostly spreading and low growing perennial plants. The height range is from 10 cm to 1 meter, so not all are at ground level. Mint plants send out runners, or stolons, to help them spread by developing roots and shoots at the nodes. This allows plants to cover up to 1 meter in stem growth, in good conditions. They are all fast growing plants and due to the spreading nature, one plant is often sufficient for most gardeners. Some mints can be invasive and it is recommended that containers or in ground barriers be used. Mints can suffer from some pests like snails and aphids and may be affected by mint rust.Rust Free Mint may also be a useful addition to the garden in addition to the many other varieties.

Most mint plants have square stems, with leaves held in opposite pairs. They are often downy with a serrated margin, with a variable leaf shape and colours ranging from green to purple. The flowers are usually white to purple and present in false whorls or verticillaster or false whorl. The corolla is usually two lipped and has 4 lobes, with the upper lobe usually the largest.

Mint plants come from across the globe and will grow in most climates, including a wide range of regions across Australia. Some are annual varieties, but in cool climate zones perennial mints may best be treated as annuals and replaced each year. Generally they have high water requirements and prefer rich soils. Mint is grown commercially in Tasmania due to the ideal conditions of long summer days in high altitudes, where temperatures average 25C during the day to 15C at night. Ideal conditions usually require full sun, but part shade may be necessary as temperatures increase in warm summer regions.

Most mints have a history of traditional medicinal or herbal use for fevers, headaches and minor ailments. These plants are often used as a digestive aid in the form or herbal tea. The essential oil is also antiseptic and may be toxic in very high doses. They should be avoided by pregnant women and must not be given, or placed next to the face of babies and young children, due to the potential for breathing difficulties associated with menthol.

Mint hybridizes very easily, so there are many varieties available to suit any garden. In fact, if you have mixed plants some may hybridize in your own garden. The most popular choices are Spearmint, Peppermint and Applemint. However, many varieties in our collection, such as Ginger Mint, Eau de Cologne, Chocolate Mint and many others are also becoming well known.

Growing Conditions

Pennyroyal requires full sun for best performance and a fertile, well-drained soil. The ground should not be too damp, since the leaves will rot or be affected by mildew if they are too wet, especially in cold winters. Drier soil in winter allows some measure of frost protection and Pennyroyal should be tolerant to minus 5 C. However this mint does like to be in moist ground, so in summer extra watering will be required.

Most mint plants have roots that travel underground, however Creeping Pennyroyal also travels on the surface. This means that wherever a part of the plant touches the ground a small root system will appear. To propagate the plant, take plant sections and pot up or allow roots to develop and replant when ready. Note, however, that Pennyroyal ‘Upright’ does not take root at the nodes and cuttings would be required for propagation. Pennyroyal also grows well from seed.

If the plant becomes too invasive in any area of the garden, simply dig that section out and discard carefully. If the plant becomes too wet in winter or spring it may suffer from a rotting type of mildew. Affected leaves should be removed and less water should be provided. Pennyroyal is a good container plant.

Medicinal Uses

Pennyroyal has a long tradition of medicinal use, despite the risk from its toxic properties due to the active constituent pulegone, even at low levels. The essential oil should never be taken internally because it may lead to liver or kidney damage, multiple organ failure or death in humans and animals. Even in relatively modern times, deaths have occurred in people and animals that consumed toxic amounts, as little as 1 ounce or approximately 30 grams. As an herbal tea, Pennyroyal was popular for treating stomach disorders and bloating, respiratory infections such as colds and influenza and to induce sweating.

A darker side to Pennyroyal is found in its use to induce abortions for unwanted pregnancies. It was also used to induce menstruation. Although the leaves were usually used, the essential oil is where the active ingredients are found in greater quantities. In earlier times it was thought that the leaves alone would create the desired effect, however it is now known to be the essential oil. Despite this knowledge, Pennyroyal should not be consumed by pregnant women due to inherent risk of uterine contractions.

Culinary Uses

Pennyroyal was a common cooking herb for the Greeks and Romans and it was used for food preparation during the Middle Ages. However, its use faded over time and today this plant is rarely used. The Ancient Greeks used to flavour their wine with Pennyroyal and at one time the leaves were used to flavour the stuffing of Hog’s Puddings – which is a type of sausage made from mince, grain and other ingredient in some areas of Britain.

Culinary uses may include use of the leaves to make strong mint sauce and for adding to iced water. Pennyroyal Mint has a strong taste and should be used sparingly. Many say the flavour is less agreeable than Peppermint or Spearmint so this may also have contributed to the lowering popularity of Pennyroyal as a culinary herb. Leaves may be picked fresh when the plant is not flowering and used or frozen for later use. They are not recommended for drying.

Other Uses

Pennyroyal had many uses including being used to eradicate pests ranging from fleas to rattlesnakes. The fresh or dried leaves are also said to be good insect repellents. However, it is important to respect the toxicity of this plant and not to use the essential oil. For example, using the oil to repel fleas by placing it on an animal may result in the death of the animal, as well as the fleas. Even spreading it around in the house or outside may result in some oil being ingested by animals, children or other people as their hands, feet and bodies touch those surfaces.

Pennyroyal Flower Seeds – Mentha Pulegium Pennyroyal Seeds

Flower Specifications

Season: Perennial

USDA Zones: 6 – 9

Height: 8 inches

Bloom Season: Mid summer

Bloom Color: Lavender

Environment: Full sun to partial shade

Soil Type: Moist, well-drained, pH 6.1 – 7.5

Planting Directions

Temperature: 68F

Average Germ Time: 7 – 21 days

Light Required: Yes

Depth: 1/8 inch

Sowing Rate: 6 – 7 seeds per plant

Moisture: Keep seed moist until germination

Plant Spacing: 18 – 24 inches

Care & Maintenance: Pennyroyal

Pennyroyal (Mentha Pulegium) – Perfect for the cottage garden, this perennial from the mint family has several benefits. Grown from Pennyroyal flower seeds this creeping plant will root from leaf nodes as it spreads. Attractive whorls of lavender flowers appear in mid to late summer, and they appear above the foliage on sturdy stems. The creeping Pennyroyal plant is a useful herb that is highly scented, and has been used to make teas, repel fleas, ants, mice, and other pests and is used in many herbal insect repellents. In addition to the repellents, Pennyroyal herb uses include container plantings such as window boxes and baskets. Pennyroyal ground cover is another use of the plant, and some even use it as a lawn alternative. It is best to confine Mentha Pulegium Pennyroyal as it can be invasive.

How To Grow Pennyroyal From Seed: Start Pennyroyal flower seeds in late winter or early spring. Pennyroyal seeds require light to germinate, so only lightly cover the flower seeds. Lightly press the herb seeds into the soil and keep moist. In late spring, after danger of frost has passed, plant outdoors into a permanent home. Water regularly the first year of establishment. Once the plant has matured, little watering is necessary and no fertilizer. To create bushy plants, pinch back the tips of young Pennyroyal herb plants. Every three years the plants should be divided and replanted in fresh compost to maintain healthy growth.

Shake ‘n Seed – We are now offering shaker bottles filled with our seed starting matrix: rich soil, gardening sand, water absorbing crystals, and starter fertilizer. This not only helps dispense your seed, but it gets it off to a great start! Simply remove lid from shaker bottle, add seed from packet, put back on lid, shake the bottle vigorously for 15 seconds, and then shake your way to beautiful new plants! Use Shake ‘n Seed over good quality soil, and then gently water to keep seed moist until it sprouts. Great for ground covers or mass planting flower seeds.


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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 . 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.

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Photo: Penny Woodward

The hot dry weather brings out all manner of insects, but the most problematic at present are the ants. When we lived in an area with sandy soils they were a constant problem coming in to the kitchen and bathrooms looking for moisture. In our current house we are surrounded by heavier clay soils and ants haven’t been a problem inside, but I have had some issues with them in pots outside. I dunk the smaller pots in soapy water and then rinse through well with fresh water. The ants exit pretty quickly. But my lime in a half wine barrel is a bit too big to move, so instead I planted pennyroyal around the outside. It took twelve months but the ants that had been nesting in the soil, in the base of the pot, disappeared.

Pennyroyal (Mentha pulegium) has leaves that are slightly hairy and narrowly elliptic, while the mauve (or sometimes white) flowers grow in tiers of whorled clusters. Sometimes called fleabane, it has a camphor/peppermint scent and does best in moist, humus-rich soils in semi-shade. Grow new plants from seed or by root division in spring and summer. It spreads rapidly from underground runners and can be a problem invading river banks and other damp areas. So don’t grow it if you live near these sorts of bush regions.

There is also a native pennyroyal (M. satureioides) that has similar properties. It grows to about 30cm, with a creeping habit and opposite green leaves that taper at both ends. The flowers are white and occur in spring. This pennyroyal will grow in dry and damp places and is found Australia-wide. The whole plant has a strong mint smell and the leaves contain oil rich in pulegone, the same oil that is found in M. pulegium. Pennyroyals act by deterring insects from feeding and can be strewn on benches or shelves to repel ants or grown near the point where they enter the house. Pennyroyals are also good mosquito and flea repellents for people and pets—grow them near dog kennels and in damp corners of the garden where mosquitoes may breed.

When I’m working in the garden, if mosquitoes are a problem, I grab a few leaves and rub them on any exposed bits of skin. This will also keep flies away for short periods.

Dried leaves of pennyroyal sprinkled on bookshelves deter silverfish. In the days of early settlement native pennyroyal was strewn on the floor, hung in bunches and used to stuff mattresses to repel fleas and bed bugs. Crushed pennyroyal leaves rubbed into your pets coats will help to keep flies and fleas away, or try pennyroyal oil made using the instructions below. Alternatively place bunches of leaves in their kennels or baskets. You can make pennyroyal oil in a wide-mouthed glass jar. Fill with crushed pennyroyal leaves, cover with an unscented oil (light olive, safflower or sunflower are all suitable). Place on a sunny windowsill for about three weeks, shaking every few days. Strain and use. Try sprinkling a few drops of pennyroyal oil into water to repel mosquitoes, or rub it on your skin.Although in the mint family, the oils found in pennyroyal are not as safe as those found in spearmint and peppermint. Pennyroyal should never be eaten by pregnant women or young children, or in excess by anyone.

By: Penny Woodward

First published: February 2014

What is Pennyroyal ?

Pennyroyal is also known as pulegium, pudding grass, mosquito plant, squaw mint, and European pennyroyal. It is a perennial herb native to Europe, as well as parts of Asia.

An American species, Hedeoma pulegioides, is closely related and is also used to produce oil, as well as Micromeria fruticosa from Turkey.

Mentha pulegium is derived from the Latin ‘puleium regium,’ which comes from its ability to destroy ‘pulices,’ or fleas. In France, it was called ‘Pouliot.’ Instead of pennyroyal, it was first known as ‘hop marjoram’ and ‘puliall royall,’ which pennyroyal is a mispronunciation of.

Because of the way the herb grows, it was aptly called ‘run by the ground’ and ‘lurk in ditch’ in old England.

The plant features creeping roots common to the Lamiaceae family. It has a smooth, round stalk and blooms with small purple flowers. The fragrant leaves are oval-shaped, greyish-green, and smell like spearmint when rubbed.

The herb can be steam distilled fresh or slightly dried to produce the oil, which is clear to pale yellow. As you might expect, it will have a very fresh, herbaceous, and minty scent.

Pennyroyal oil blends well with citronella (Cymbopogon nardus), geranium (Pelargonium graveolens), rosemary (Rosmarinus officinalis), and sage (Salvia officinalis).

Pennyroyal Essential Oil Uses

Pennyroyal is an herb with a medicinal history almost as long as herbal medicine itself.

Its healing qualities date back to the first century, in the time of Pedanius Dioscorides. In his five-volume work, De Materia Medica, you can find pennyroyal mentioned for a wide variety of ailments, particularly those of women.

Likewise, the Roman naturalist Pliny the Elder described many virtues of the herb during that time as well, such as its ability to purify water.

Ancient Uses

This particular mint was one of many such herbs that were referred to as ‘pot herbs’ for their wide deployment in culinary use.

One of the pennyroyal’s former names, pudding grass, was from a time when it was mixed with currants, spices, and flour. This was then stuffed into a hog’s entrails. It was an old-time stuffing, which at the time was deemed pudding.

Flavoring & Scenting

Pennyroyal is said to resemble spearmint (Mentha spicata) in taste. It has been used throughout history to flavor wine and food, as well as to make herbal teas.

As it also smells like spearmint, it has been used to scent colognes, perfumes, detergents, and soaps.

Historical Medicinal Uses

Before there were tests to determine the toxicity of a substance, pennyroyal was considered to be one of the most important medicinal herbs.

In Culpepper’s The Complete Herbal, he begins the section on the herb by saying, “Pennyroyal is so well known unto all, I mean the common kind, that it needs no description.”

He then states the methods in which Dioscorides used the plant:

  • Thinning out thick phlegm
  • Bringing on menstruation
  • Warming any cold part
  • Abortions
  • Causing vomiting when mixed with water and vinegar
  • As an antidote to poisonous bites and stings when mixed with wine
  • Mixed with vinegar to awaken those who have fainted
  • Dried and burnt to strengthen gums
  • Soothes gout
  • Made into plaster to remove facial marks
  • Soothes itches when used as a wash
  • Bruised and mixed with vinegar to clean ulcers
  • Eliminates bruises of the eyes and burns on the face
  • Calms toothache pain when boiled in wine and mixed with honey and salt
  • Used as a wrap to take away joint pain

He goes on to write that Pliny added his own remedies to Dioscorides:

  • Mixed with other mints in vinegar and placed under the nose to rouse someone who has fainted
  • Ease headaches
  • Relieved breast and stomach aches
  • Mixed with honey, salt, and vinegar to calm cramps and ‘convulsions of the sinews’
  • Cough remedy when boiled with milk, as well as healing mouth sores
  • Brought about menstruation and abortion when drank in wine

Culpepper further notes that Matthiolus, a doctor in Siena that died in 1577, came up with his own uses for the well-rounded herb:

  • A decoction of the herb helps edema and jaundice
  • Heals headaches and other issues caused by cold
  • Clears eyesight
  • Eased burns when applied with barley
  • Soothed earaches when applied within
  • Gave energy to the lethargic

In a latter part of the book, there is an interesting synopsis of the virtues of this herb:

“Pulegium: Pennyroyal; hot and dry in the third degree; provokes urine, breaks the stone in the reins, strengthens women’s backs, provokes the menses, easeth their labour in child-bed, brings away the placenta, stays vomiting, strengthens the brain, breaks wind, and helps the vertigo.”

In yet another text, Mother’s Remedies: Over One Thousand Tried and Tested Remedies from Mothers of the United States and Canada, there were even more uses for this wonder.

One of the dosing instructions was an infusion of the herb, one ounce to a pint of water steeped but not boiled, that could be used without reserve. The other dose called for 2-5 drops of the oil.

These could be used for:

  • Stimulant purposes
  • Bringing on sweating
  • Menstrual troubles
  • Suppressed lochia (the vaginal discharge that occurs after childbirth for a couple days up to six weeks)
  • Suppressed menses
  • Flatulent colic in children

Aid Drowning ‘Victims’

Since it has such a reputation for being an enemy of bugs, it is interesting to note that in another text from days gone by, The Old English Herbals, that pennyroyal had another use.

It stated that the warm ashes of the burnt herb could be used to revive drowning flies and bees. Upon placing them in the ash, “they shall recover their lyfe after a little tyme as by ye space of one houre.”

Up until scientists discovered how dangerous the herb was, the answer to ‘what is pennyroyal good for?’ was: a lot!

Pennyroyal Essential Oil Benefits

The side effects and dangers of using pennyroyal essential oil far outweigh the benefits.


The herb derives its name from its ability to kill fleas and has been used for this and other pests throughout the ages.

The oil is still used to some degree as an insecticide and can be found in some commercial preparations. Unfortunately, you can also find countless recipes online using pennyroyal to keep fleas, ticks, and other insects off of yourself and your pets.

They generally advise a number of pennyroyal essential oil drops in some water with other oils, like peppermint, citronella, and lemongrass. Then you shake and spray on your skin or on your pets and the bugs stay away.

Please do not do this.

While at least some of the recipes I have seen recommend not to do this if you are pregnant, it is wise not to do this at all.

This applies to using the oil on animals as well. There have been reports of animals dying from pennyroyal oil poisoning when well-meaning owners have treated them for fleas with the substance. This goes for both dogs and cats.

Tisserand recommends a dermal maximum of 1.3% based on a pulegone level of 86.7% with a maximum dermal limit of 1% for that constituent. It is wholly contraindicated during pregnancy due to the hepatotoxic and carcinogenic danger of this naturally-occurring chemical.

Tea Benefits

As a tea, pennyroyal was used for many things. It was recommended to steep the herb and drink in order to use as a:

  • Anthelmintic to expel parasites and worms
  • Antispasmodic for cramping and convulsions
  • Antitussive to relieve cough
  • Carminative to reduce flatulence and abdominal bloating
  • Decongestant and expectorant to thin and reduce mucus
  • Digestive and stomachic tonic to aid in digestion and relieve stomach issues
  • Diaphoretic to induce sweating
  • Emmenagogue to induce menses
  • Febrifuge to reduce fever

Pennyroyal tea was also applied topically as a(n):

  • Antiseptic to clean and heal wounds
  • Insect repellant, particularly to keep gnats away from the face
  • Refrigerant to cool the body and reduce fever
  • Rubefacient to redden the skin as a counter-irritant

In Mother’s Remedies, it was stated that a “…five-cent package can be bought at any drug store.”

Side-Effects of Pennyroyal

According to WebMD, there are numerous detrimental effects of using pennyroyal:

  • Kidney, liver, and nervous system damage
  • Nausea, vomiting, and abdominal pain
  • Burning sensation in the throat
  • Restlessness
  • Dizziness
  • Seizures
  • Confusion
  • Hearing and vision problems
  • Abortion
  • Increased blood pressure
  • Liver failure
  • Brain damage
  • Death

They further point out that existing liver or kidney damage could be made worse by ingesting pennyroyal.

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Pennyroyal Essential Oil Research, Facts, and Studies

Food and Drug Administration (FDA)

With all of the danger surrounding pennyroyal, it is interesting to note that the herb, both American and European, is listed on the “Everything Added to Food in the United States” (EAFUC) list.

Herbal Tea Toxicity in Infants

Two infants were severely hurt, one fatally, after ingesting mint tea. Upon examination, it was determined that the teas contained pennyroyal.

The first infant developed sudden cerebral edema, liver failure, and necrosis. The child tested positive for only menthofuran but died from its injuries.

The second infant tested positive for both pulegone and menthofuran. The baby developed epileptic encephalopathy and hepatic dysfunction but survived.

Statistics of Self-Induced Abortion Attempts

There are numerous cases throughout history when women have attempted to induce abortion by using pennyroyal in various forms.

1897 In Britain, a 23-year old woman took a tablespoon of pennyroyal oil in order to induce menstruation, which had been absent for six months. She came into the hospital after vomiting for four days.

The doctor, W.T. Allen of the Parish Missionary in Liverpool, treated her with morphia (morphine), and rectal alimentation (nourishment through rectal delivery), which resolved the vomiting. However, her condition continued to deteriorate, and she died eight days after ingestion, on March 19, 1897.

The druggist who had sold the young lady the pennyroyal stated he had never heard of poisoning by the substance in his 30 years of work.

(c) 1909: A man was convicted after prescribing pennyroyal pills. The woman had a miscarriage and died two months later.

1912: This case also involved pills, which were ingested by a 16-year-old trying to abort her baby. This one was also fatal.

In 1954, there was a case in which a woman swallowed a vial of pennyroyal, purchased another the day after, and drank that as well. She went to her doctor after feeling ill, who prescribed codeine pills.

When she was later admitted to the hospital and it was discovered she had severe vaginal bleeding, she confessed to taking the poison in an effort to induce the abortion of a three-month pregnancy. This was on October 15th. She died on October 28th, after suffering severe liver and kidney damage.

1961: A 23-year old woman took three pennyroyal tablets 3-4 times a day for four days in an effort to induce abortion. She ended up having epileptic fits, hallucinations, and severe confusion. After a brief hospitalization, she survived and later delivered a daughter.

1978: An 18-year old ingested two ounces of oil to induce abortion. She died after seven days.

1994: In this case, it is unclear whether the 24-year-old woman died from complications from an ectopic pregnancy or from pennyroyal poisoning. She had drunk a pennyroyal extract-infused herbal tea prior to her death.

Herbal Toxin

An abstract from 1996 stated that the herb, which is widely available, is an “herbal toxin of public health importance.” The authors propose a greater understanding of the toxic mechanism and stricter control of the herb to the general public.

Treatment for Pennyroyal Toxicity

The antidote for overdoses of pennyroyal is glutathione, which detoxifies the metabolic toxins. In hospital settings, N-acetylcysteine is administered in a similar way as it is for acetaminophen overdose.


Pennyroyal’s claim to fame throughout the years has been as a natural abortifacient. This may be a fallacy, as pointed out by Lise Alschuler, Bastyr University botanical medicine chair:

“Pennyroyal oil has a long folk history as an abortifacient. It isn’t really. In most cases, it fails to induce abortion. What women are doing in these cases is creating such high toxicity that their own body is unable to sustain the pregnancy.

… If pennyroyal oil is to work as an abortifacient, it’s going to work because it’s poisoning the mother.”

While the plant has been used for a myriad of ways since the dawn of natural medicine, there is no way to determine a therapeutic dose of this often unreliable plant.

It is advised to stay away from pennyroyal essential oil, especially as the toxic pulegone is concentrated in it.

This is true no matter which pennyroyal you get the oil from, whether it is the European, Turkish or North American type.


DISCLAIMER: Momprepares.com is intended to be used for educational and informational purposes only. For safe use, please contact your medical practictioner or health care provider. Momprepares.com, its parent company, and subsidiaries does not assume liability for any actions taken after visiting these pages and does not assume liability if one misuses essential oils. These statements have not been evaluated by the Food and Drug Administration. This article is not intended to diagnose, treat, cure, or prevent disease.

About Mom Prepares

Mom Prepares is an essential oils and natural living blog. We bridge the gap between scientific research and the everyday essential oils user. If you’re new to essential oils, you can download our free eBook: The Beginner’s Guide to Essential Oils.

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Why not, I can see how smells could lift a persons mood and alleviate Like its cousins, pennyroyal can be used as a culinary herb and was common The last burning question is “does pennyroyal oil induce abortions?. Peppermint essential oil smells like fresh mint with a hint of pepper. Like pennyroyal (Mentha pulegium), peppermint oil contains pulegone. He spoke of it increasing the appetite, saying, “The smell of Mint does stir up the minde and the. Used in low doses even the pennyroyal essential oil can help. Because it contains cinnamaldehyde, just like the Cinnamon Bark oil, you’ll have to also use a And do a thorough research before using it for the first time. . Blends well with: The Boldo essential oil has no use in Aromatherapy because of its smell.

It bears the prefix “Mentha” in its botanical name since it smells like mint when its leaves are crushed. The essential oil of penny royal is derived. We don’t hear about pennyroyal oil often. When we do, we have reason to be greatly concerned. Although poisonings with pennyroyal oil are rare, they can be . Mentha pulegium, commonly (European) pennyroyal, or pennyrile, also called squaw mint, Galen only listed pennyroyal as an emmenagogue, as did Oribasius. Some flea collars for pets have pennyroyal oil or the herb can be crushed in the . and administration of emetics, or vomiting inducing agents, like activated.

The use of pennyroyal oil in products has become controversial when products using the oil were implicated in the deaths of two women. The herb is known to. Learn more about Pennyroyal uses, effectiveness, possible side effects, interactions, dosage, user ratings and products that contain Pennyroyal. I’d also just like to address American penny royal this is likely to be Hedeoma pulegioides, smell has similarities but is extremely bitter in comparison.

humbvapartdysp.tk: NOW Essential Oils, Pennyroyal Oil, 1-Ounce: Herbal Supplements It will not kill spiders–but they do not like the smell of the oil and steer clear. This would be a fair question. The penny royal essential oil we are offering here contains % pulegone, I confirm again I’d also just like to address American penny royal – this is likely to be – Hedeoma pulegioides, smell has similarities spearmint which are both from the Mentha genesus like European penny royal. Pennyroyal toxicity. I have some questions about pennyroyal for you guys. from them (some people really like the taste, especially of American pennyroyal), generally roll around in it and embrace it as a wonderful-smelling part of your life. effects, as would even a fraction of a teaspoon of most herbal essential oils .

Penny Royal ORGANIC Essential Oil

Adam Michael has this to say “So why sell penny royal? This would be a fair question. First of all the key chemical that causes great concern is called ‘pulegone’ which is a monoterpene ketone that is actually a starting material for the manufacture of synthetic menthol but more importantly when ingested in high doses has been proven to cause severe toxicity and in extreme cases death. Most books and papers state penny royal essential oil contains at least 60% ‘pulegone’, (Barnes et al., 2002). The penny royal essential oil we are offering here contains 1.6% pulegone, I confirm again – 1.6% pulegone, that is less than what is found in peppermint oil – Mentha pipperita (about 4%). I’d also just like to address American penny royal – this is likely to be – Hedeoma pulegioides, smell has similarities but is extremely bitter in comparison.

The other major constituent is actually pipperitone at a staggering 45.52%. Other constituents are eucalyptol (1.8 cineole), camphor, limonene and cis thujone collectively accounting for just over 16% of the oil.

The colour is clear yellow, it is of thin viscosity and obtained by steam distillation of the dried leaves and flowering tops. The smell is very clean, fresh, strong, herbaceous and similar to smelling peppermit and spearmint which are both from the Mentha genesus like European penny royal.

I was impressed to learn that this oil is also referred to as mosquito plant, pudding grass and squaw mint. I understand the mosquito reference is because penny royal is a mosquito deterrent.”

If you are pregnant please keep away from this essential oil.

Botanical Name: Mentha pulegium

Origin: Albania

Certified Organic – CERES

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