Used internally in the recommended amounts, pennyroyal is generally safe, though an occasional person may experience intestinal upset or temporary dizziness.⁶ Pulegone and its toxic metabolites, particularly menthofuran, damage the liver and nerves if taken in sufficiently large quantities.⁷ If used during pregnancy, pennyroyal may cause foetal death by liver and brain damage as well as promote uterine contractions to expel the foetus.⁸ Therefore pregnant or nursing women should absolutely avoid pennyroyal in any form. The traditional use of the herb to induce an abortion has led to many reports of nervous system toxicity in pregnant women. Internal ingestion of pennyroyal volatile oil should be avoided by everyone. People with liver failure or kidney failure, and all children, should avoid pennyroyal. Signs and symptoms of pennyroyal toxicity include severe stomach pain, dizziness, seizures, vomiting, difficulty walking, and coma. Since 1905, 18 cases of injury (with complete recovery in every case) and four deaths related to pennyroyal have been reported in the medical literature.⁹ The majority of acute poisonings and deaths reported with pennyroyal have been in cases of women using the oil attempting to induce an abortion.