Pennyroyal Oil: Why It Is Dangerous
Pennyroyal oil has caused liver failure and deaths when swallowed. What the poison and liver sources say, why pennyroyal is not a safe remedy, and who to call.
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Urgent first. Pennyroyal oil taken by mouth is highly toxic. If anyone has swallowed pennyroyal oil, or may have, call Poison Help at 1-800-222-1222 (US) right away. Call 911 for collapse, a seizure or trouble breathing. [1] LiverTox, the US National Institutes of Health liver-injury database, says that when taken by mouth, pennyroyal oil is highly toxic and has been linked to several instances of toxic liver injury and death. [2] See Poisoning: what to do first and, for other countries, Poison Help by country. This page gives no preparation or use information on purpose.
Which plant, which part
LiverTox describes pennyroyal as an herbal extract or oil derived from the leaves of a mint genus plant, Mentha pulegium. [2] GBIF accepts Mentha pulegium L. (the mint family, Lamiaceae). [4] A different plant with a similar common name, American pennyroyal, Hedeoma pulegioides (L.) Pers., is also accepted on GBIF in the same family. [5] The sources we read about poisoning do not always say which plant was involved, so a label saying only "pennyroyal" does not tell you which plant is inside. We do not give any identification or foraging advice; for plant questions, ask poison help or a local botanist or extension service.Traditional use
Traditional use only, not proof, and the use caused harm. LiverTox says pennyroyal oil was used in the past as an insect repellent and an abortifacient (a substance taken to end a pregnancy). [2] A 1996 medical report says pennyroyal has long been used as an abortifacient despite its potentially lethal liver toxicity. [3] The sources we read give no region-specific history.What the sources found
| Question | What the source found | Strength of evidence | Population and form studied |
|---|---|---|---|
| Is pennyroyal oil toxic to the liver? | A 1996 report described four people who swallowed pennyroyal: one died, one received N-acetylcysteine (a liver-protecting hospital treatment), and two swallowed minimally toxic amounts. A review of 18 earlier cases documented moderate to severe toxicity in those exposed to at least 10 mL of pennyroyal oil. [3] | Evidence of harm (case reports and case series) | People who swallowed the herb or oil; not controlled trials [3] |
| Other organs | A 2023 review of herbal abortifacients lists pennyroyal among those with significant morbidity and mortality and says liver, heart, kidney and blood effects need special attention in poisoned patients. [6] | Evidence of harm (narrative review) | People who used herbal abortifacients [6] |
| Does pennyroyal treat any condition? | Proper evidence not found. We searched PubMed for pennyroyal and found poisoning reports and laboratory studies, but no trial of benefit in people. | Traditional use only | Not applicable |
| Is pennyroyal tea safer than the oil? | Proper evidence not found in the sources we read; the reports describe the herb or oil. | Insufficient evidence | Not applicable |
No amount is shown to be safe in the sources we read. The "10 mL" figure above is the level at which earlier case reports documented serious toxicity, and it is not a safe limit.
Who is most at risk
- Anyone who is pregnant. A 2023 review names pennyroyal among herbal abortifacients with serious illness and death. [6] If someone is pregnant and wants to end the pregnancy or has concerns, a clinician can discuss options that do not put the liver at risk. See pregnancy and breastfeeding.
- Children. Poison Control says children have thin skin and immature livers, which might make them more susceptible to toxic effects than adults. [1]
- People with liver disease or on medicines cleared by the liver. Specific interactions are not described in the sources we read; ask a pharmacist. See liver safety and how interactions work.
If you feel unwell or in crisis
If someone has swallowed pennyroyal to harm themselves, call 911, and in the US the 988 Suicide & Crisis Lifeline can be reached by calling or texting 988.What to do instead
Do not use pennyroyal oil. Ask a pharmacist or clinician about the symptom you were hoping to treat. For insect repellent questions see essential oils for insects. Pets: ask an animal poison line; see pet poisoning. Quality and adulteration of oils are covered in essential oil purity and adulteration.Frequently asked questions
Is pennyroyal oil dangerous?
Yes. LiverTox says oral pennyroyal oil is highly toxic and linked to toxic liver injury and death. [2] Poison Control says it is highly poisonous to the liver. [1]
Is pennyroyal tea safe?
Proper evidence not found that any form is safe. The sources we read describe harm from the herb and oil, and do not tell us tea is safe.
Has pennyroyal been used to end pregnancies?
Yes, historically, and with documented lethal liver toxicity. [3] A clinician can discuss safe options.
What should I do if someone swallowed pennyroyal oil?
Call Poison Help at 1-800-222-1222 (US) right away. Call 911 for collapse, a seizure or trouble breathing. [1]
Is pennyroyal the same as American pennyroyal?
No. They are different plants, Mentha pulegium and Hedeoma pulegioides, with a shared common name. [4][5]
References
- Essential oils: Poisonous when misused (Poison Control). Read 2026-10-23.
- Pennyroyal Oil (LiverTox, National Institutes of Health). Read 2026-10-23.
- Pennyroyal toxicity: measurement of toxic metabolite levels in two cases and review of the literature. Ann Intern Med 1996. Read 2026-10-23.
- Mentha pulegium L. (GBIF Backbone Taxonomy). Read 2026-10-23.
- Hedeoma pulegioides (L.) Pers. (GBIF Backbone Taxonomy). Read 2026-10-23.
- Toxicities of herbal abortifacients. Am J Emerg Med 2023. Read 2026-10-23.