Essential oil related seizures (EORS): A multi-center prospective study on essential oils and seizures in adults

Essential oils (EOs) like eucalyptus and camphor have pro-convulsant properties. These EOs are present in many over- the- counter balms and oils. The effect of exposure to these EOs and occurrence of seizure is not systematically studied. The aim of this study was to evaluate the relationship between essential oils and the first episode of seizure and breakthrough seizures in known epileptic patients.

This was a multi-center prospective study, conducted in four hospitals over four years. Every person presenting with the first episode of seizure or breakthrough seizure was asked about exposure to EOs, mode of exposure, time to onset of a seizure in relationship to exposure, duration of seizure, type of seizure, and antiepileptic drug therapy.

During the four-year period there were 55 patients with essential oil-related seizure (EORS). 22(40 %) had essential oil-induced seizures (EOIS) and 33(60 %) had essential oil-provoked seizures (EOPS). The female: male ratio was 1:1.1, the age of the patients ranged from 8 months to 77 years. In the EOIS group, 95 % had generalized tonic-clonic seizures and 5% had focal impaired awareness seizures. In the EOPS group, 42.4 % had focal impaired awareness seizures, 27.3 % generalized tonic-clonic seizures, 15 % focal to bilateral tonic-clonic seizures, and 15 % focal aware motor seizures. EOs implicated were preparations containing eucalyptus and camphor.

Exposure to essential oils of eucalyptus and camphor is an under-recognized cause of the first and breakthrough seizure. Identifying the true causative factor will prevent unnecessary antiepileptic drug therapy and future recurrence.