Bottom Line: Pennyroyal is an extremly toxic herb that has caused multi-organ failure and death in several people. It should be avoided.
Pennyroyal is a flowering plant that was used in folk medicine to treat various minor ailments, including colic and bronchitis, but is better known for its abortion-inducing effects. Scientists are unsure exactly how pennyroyal exerts these effects (which, it should be noted, have not been consistently shown to occur), but it is thought that the herb causes irritation of the uterus, leading to contractions. However, lethal doses are necessary for this to occur, injuring or killing the mother as well as the fetus. The extensive toxicity of pennyroyal is due to a substance called pugelone, which is metabolized in the liver to highly toxic molecules that cause tissue damage in the internal organs. Studies in both animals and humans show that pulegone is directly toxic to the nervous system.
**NOTE: No clinical trials have shown pennyroyal to be effective in treating any of the following conditions. Pennyroyal has been found to be extremely toxic and therefore cannot be recommended to treat such conditions.
To induce menstruation
To treat lung conditions such as asthma and bronchitis
To treat cancer
To relieve stomach and intestinal gas (colic)
To treat the common cold and the flu
To treat headaches
To induce abortion
To reduce inflammation
As an insect repellant
To relieve the symptoms of premenstrual syndrome (PMS)
Laboratory analysis of over-the-counter pennyroyal leaf products found contamination with low levels of bacteria, fungi, and yeast.
This product is regulated by the FDA as a dietary supplement. Unlike approved drugs, supplements are not required to be manufactured under specific standardized conditions. This product may not contain the labeled amount or may be contaminated. In addition, it may not have been tested for safety or effectiveness.
Toxicity: At least 24 cases of pennyroyal toxicity are have been reported, including total liver failure, acute kidney failure, hypoglycemia (low blood sugar), blood clotting problems, metabolic acidosis (acidic pH of the blood), GI hemorrhage, lung congestion, mental status changes, cerebral edema, seizures, disseminated intravascular coagulation (blood clots forming in the blood vessels), and death. There are several reports of young women who took pennyroyal oil for its abortion-inducing effects and died of multi-organ failure. One infant given pennyroyal tea for respiratory infections died from organ failure.
An herbal extract oil or tea derived from the leaves and flowering tops of the plant. This supplement is used in folklore medicine to induce abortion and menses and to treat inflammatory conditions, chronic bronchitis, minor ailments and colic in infants. Small amounts of the oil are approved by the Food and Drug Administration for use as a flavoring agent. Pennyroyal oil contains several monoterpenes, principally pulegone, which has known toxic effects on the liver and lungs. Oxidative metabolites of pugelone, such as menthofuran, are oxidized further by cytochrome P450 to reactive intermediates that form adducts with cellular proteins and cause organ damage. Ingestion of pennyroyal oil in adults or tea in children causes severe toxicity (4)(5), including hepatic failure, acute renal failure, coagulopathies, metabolic acidosis, GI hemorrhage, pulmonary congestion with consolidation, cerebral edema, seizures, disseminated intravascular coagulation, and death. This is a dangerous herb and should not be used.
The exact mechanism of action is unknown. Pennyroyal's abortifacient properties are thought due to irritation of the uterus, causing contractions, but lethal doses are necessary for this to occur and the effect is inconsistent. Pennyroyal's mint properties, attributable to the menthol component, theoretically may act in dilating respiratory passages in bronchitis or asthma when consumed as a tea (5). European and American pennyroyal oil consist of 80-90% and 16-30% (R)-(+)-pulegone, respectively, which is oxidized by cytochrome P450 to menthofuran (about 50%) and other toxic metabolites (4). Animal and human studies show that pulegone is directly neurotoxic. Menthofuran decreases glucose-6-phosphatase activity in rat models, causing hypoglycemia (1).
Absorption Studies in rats show a single 150 mg/kg intraperitoneal dose of pulegone produces peak plasma levels of 13.5 ± 3.0 mg/ml after about 15 minutes and a half-life of approximately one hour. Menthofuran levels peak at 7.0 ± 1.2 mg/ml one hour after pulegone administration, with a half-life of about 2 hours (10). Distribution Pulegone is oxidized by cytochrome P450 2E1, 1A2, and 2C19 to its proximate toxic metabolite menthofuran (about 50%), and other reactive metabolites (8). Menthofuran is thought responsible for less than half of the toxicity attributable to pennyroyal oil. Studies identify 2-Z-(2'-keto-4'-methylcyclohexylidene)propanal, an unsaturated keto aldehyde that forms adducts with cellular proteins, as the ultimate chemically reactive metabolite. Menthofuran also is metabolized to 4-hydroxy-4-methyl-2-cyclohexenone and p-cresol, a known liver and lung toxin (6). End products of cytochrome P450 oxidation of menthofuran include hydroxymenthofuran and its nontoxic tautomers mintlactone and isomintlactone (11). Pugelone may be metabolized by P450 via two other pathways to as yet unidentified electrophilic reactive species, which, together with pulegone, deplete glutathione (GSH) in liver and plasma by forming covalent adducts with its nucleophilic cysteinyl sulfhydryl group (7). Depletion of GSH further increases the hepatotoxicity induced by pulegone in rat models (9). Pennyroyal oil causes centrilobular liver necrosis in a dose-dependent manner (1). Excretion At least 14 pulegone metabolites, including menthofuran, are excreted in the urine (12) and at least 10 phase II metabolites are found conjugated to glutathione and glucuronide in bile.
Due to its abortifacient effects, pennyroyal should not be consumed by pregnant or breast-feeding women. Due to its toxic effects, pennyroyal should not be consumed under any circumstances.
Reported: Dizziness, weakness, syncope, hallucinations, abdominal cramps, nausea, GI upset, pupillary changes, hepatotoxicity, renal injury. Toxicity: At least 24 cases of pennyroyal toxicity are in the literature, reporting fulminant hepatic failure, acute renal failure, hypoglycemia, coagulopathy, metabolic acidosis, GI hemorrhage, pulmonary congestion with consolidation, mental status changes, cerebral edema, seizures, disseminated intravascular coagulation, and death. Pennyroyal oil ingestion is treated with gastric lavage, activated charcoal, and N-acetylcysteine in patients evaluated soon after ingestion. Case Report (Oil): A 24-year-old woman ingested pennyroyal extract for over 2 weeks and, after acute ingestion, developed abdominal cramps, chills, vomiting, syncope, cardiopulmonary arrest and multiorgan failure leading to coma and death. Exploratory laparotomy showed a hemorrhagic ectopic pregnancy (13). An 18-year old ingested 30 ml of pennyroyal oil and developed abdominal pain, vomiting, coagulopathy, and died one week later from cardiopulmonary arrest and multiple organ failure (5). Case Report (Tea): An 8-week old boy, after ingesting 120 ml of homegrown pennyroyal mint tea to treat a suspected infection, experienced multiple organ failure, including confluent hepatocellular necrosis, kidney hemorrhage and necrosis, bilateral lung consolidation with diffuse alveolar damage and hemorrhage, and diffuse cerebral edema with acute ischemic necrosis and isolated vacuolation of the midbrain. The infant died 4 days after admission. A 6-month old boy developed acute hepatic injury, seizures, and sinus hemorrhage after regular consumption of pennyroyal tea, and recovered after 2 months of hospitalization (4).
