Pennyroyal Toxic?

Updated 2026-03-06| 4 min read| 2,988 found this helpful

All parts of pennyroyal are toxic to humans and common domestic animals if ingested

Toxic components are pulegone and menthofuran, monoterpenes present in the plant's essential oil

Ingestion can lead to severe complications including liver necrosis, DIC, seizures, and fatal outcomes

FAQ

Is Pennyroyal toxic to Humans?

Nausea, vomiting, gastrointestinal bleeding, central nervous system seizures, coma, coagulation disorders, disseminated intravascular coagulation (DIC), liver necrosis, death (Moderate)

Is Pennyroyal toxic to Cats?

Expected to align with human symptoms, including gastrointestinal distress, neurological dysfunction, organ damage, and fatal outcomes if untreated (Moderate)

Is Pennyroyal toxic to Dogs?

Expected to align with human symptoms, including gastrointestinal distress, neurological dysfunction, organ damage, and fatal outcomes if untreated (Moderate)

Is Pennyroyal toxic to Horses?

Expected to align with human symptoms, including gastrointestinal distress, neurological dysfunction, organ damage, and fatal outcomes if untreated (Moderate)

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Toxicity Details

Humans

Moderate

Nausea, vomiting, gastrointestinal bleeding, central nervous system seizures, coma, coagulation disorders, disseminated intravascular coagulation (DIC), liver necrosis, death

Cats

Moderate

Expected to align with human symptoms, including gastrointestinal distress, neurological dysfunction, organ damage, and fatal outcomes if untreated

Dogs

Moderate

Expected to align with human symptoms, including gastrointestinal distress, neurological dysfunction, organ damage, and fatal outcomes if untreated

Horses

Moderate

Expected to align with human symptoms, including gastrointestinal distress, neurological dysfunction, organ damage, and fatal outcomes if untreated

Toxicity Snapshot

Toxic PartsAll parts of the plant

Exposure RouteIngestion of raw plant material or concentrated essential oil, accidental dermal absorption of undiluted essential oil

Toxic CompoundsPulegone; Menthofuran

First Aid & Prevention

First 30 Minutes

• Immediately remove any remaining pennyroyal plant or product from the reach of the exposed person/animal
• Contact a medical professional or veterinarian immediately for guidance on decontamination steps
• Do not induce vomiting, give food/drinks, or administer home remedies unless explicitly instructed by a healthcare provider

Contact Vet Immediately

• If your pet has ingested any quantity of pennyroyal plant or its essential oil
• If your pet exhibits symptoms including vomiting, seizures, lethargy, unusual bleeding, or jaundice after suspected exposure
• If your pet has had dermal exposure to concentrated pennyroyal essential oil

Prevention

• Avoid planting pennyroyal in yards or gardens accessible to children and domestic animals
• Clearly label any pennyroyal-containing herbal or essential oil products to prevent accidental ingestion or misuse
• Never apply pennyroyal essential oil to the skin or fur of pets, as it is highly toxic even in small doses

Treatment & Prognosis

• Decontamination via induced vomiting or activated charcoal administration as directed by a medical professional or veterinarian
• Supportive care including IV fluid therapy, anti-seizure medication, and coagulation support as clinically indicated
• Long-term monitoring of liver function and coagulation parameters for 24 to 72 hours post-exposure to identify delayed toxic effects

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Professional Toxicology

Scientific NameMentha pulegium L.

AliasesSquaw mint、Mosquito plant、Pudding grass

Toxicity Grade

HumansModerate

CatsModerate

DogsModerate

HorsesModerate

Target Organs

Gastrointestinal tractLiverCentral nervous systemVascular system

Mechanism of Action

• Toxic monoterpenes in pennyroyal's essential oil are rapidly absorbed after ingestion, causing direct cytotoxic damage to body tissues

• Metabolites of pulegone and menthofuran induce hepatocellular damage leading to liver necrosis, and disrupt normal blood coagulation pathways

• Neurotoxic effects of the compounds trigger central nervous system seizures and coma in severe exposure cases

Other Species Risk (CliniTox)

Information from CliniTox veterinary text.

Ruminants (cattle, sheep, goats): Ingestion of significant quantities of pennyroyal in forage can cause liver damage, coagulation disorders, and potentially fatal outcomes

Small companion mammals (rabbits, guinea pigs, hamsters): Even small amounts of ingestion can cause gastrointestinal distress, neurological dysfunction, coagulation disorders, and death if left untreated

Confusion Risk

The following plants look similar and may be confused:

Other Mentha species Mentha spp.

Visually similar to edible culinary mint varieties; key differentiator is pennyroyal's distinctly pungent, camphor-like aroma compared to milder culinary mints

Lemon balm Melissa officinalis

Shares serrated leaf structure with pennyroyal; key differentiator is lemon balm's strong citrus scent, and it is non-toxic

White dead-nettle Lamium album

Shares square stem and opposite leaf arrangement common to Lamiaceae family plants; key differentiator is its distinctive white hooded flowers, and it is non-toxic

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Related Toxic Plants

Perilla mint

Perilla frutescens

Severe

Ground ivy

Glechoma hederacea

Moderate

Spanish lavender

Lavandula stoechas

Low

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Data Sources

1. CliniTox (Universität Zürich)

This information is for reference only and does not constitute medical advice. If ingestion or poisoning is suspected, seek medical or veterinary attention immediately.