Background: Hepatic and neurologic injury developed in two infants after ingestion of mint tea. Examination of the mint plants, from which the teas were brewed, indicated that they contained the toxic agent pennyroyal oil.
Methods: Sera from each infant were analyzed for the toxic constituents of pennyroyal oil, including pulegone and its metabolite menthofuran.
Results: Fulminant liver failure with cerebral edema and necrosis developed in the first infant, who died. This infant was positive only for menthofuran (10 ng/mL). In the other infant, who was positive for both pulegone (25 ng/mL) and menthofuran (41 ng/mL), hepatic dysfunction and a severe epileptic encephalopathy developed.
Conclusion: Pennyroyal oil is a highly toxic agent that may cause both hepatic and neurologic injury if ingested. A potential source of pennyroyal oil is certain mint teas mistakenly used as home remedies to treat minor ailments and colic in infants. Physicians should consider pennyroyal oil poisoning as a possible cause of hepatic and neurologic injury in infants, particularly if the infants may have been given home-brewed mint teas.