Essential oils are a popular alternative medicine therapy. These concentrated plant oils contain many beneficial and harmful compounds, some of which have pro-seizure and antiseizure properties. Findings of a recent study report a relationship between essential oil use and first-time and breakthrough seizures.

A 2019 systematic review found that lemongrass, lavender, clove, and dill may have antiseizure properties that should be explored for drug development. The review also found that other essential oils have pro-seizure effects. Consumption of essential oils such as sage, hyssop, rosemary, camphor, pennyroyal, eucalyptus, cedar, thuja, and fennel may induce seizures in those with and without epilepsy.

The investigators collected data on seizure incidence and essential oil use from four hospitals in India for four years between 2014 and 2018. They asked every patient receiving care for a first-time seizure or breakthrough seizures about their exposure to essential oils, mode of exposure, time between exposure and seizure onset, duration of seizure, type of seizure, and antiepileptic drug therapy.

The researchers recorded 55 essential oil-related seizures during data collection including 22 cases of essential oil-induced seizures in those without epilepsy and 33 cases of essential oil-provoked seizures in those with diagnosed epilepsy. They found that topical use, inhalation, or ingestion of essential oil preparations containing eucalyptus and camphor were the cause. In those without epilepsy, topical application was the cause in 73 percent of cases, inhalation in 23 percent, and ingestion in 4 percent. In those with diagnosed epilepsy, topical application was the cause in 79 percent of cases, inhalation in 15 percent, and ingestion in 6 percent.

The authors concluded that exposure to essential oils containing eucalyptus and camphor is an under-recognized cause of first-time seizures and breakthrough seizures.

• Link to full report.