Essential oils – extracts of certain plants containing compounds that capture the "essence" of their scent – are an extremely contentious topic in medicine. With a huge array of oils utilized in everything from stress to childbirth, sellers often make bold claims about their efficacy and applications with, in many cases, limited or no robust evidence backing them up. This isn’t to say that every single essential oil is bad – animal studies involving peppermint, for example, suggest that it can help aid digestion. But the distinct lack of regulation and extreme claims made about many of these oils creates an industry shrouded in pseudoscience.
However, sometimes these oils can be downright dangerous.
A specific group of essential oils, including eucalyptus and camphor, have pro-convulsant properties. This means they can act within the nervous system to induce convulsions and seizures, which can be a serious problem for people with pre-existing epilepsy. Despite this, these oils are regularly found in products readily available to purchase, often without warnings of their shortcomings.
Now, a new study has discovered that these essential oils could be to blame for seizures in a significant proportion of patients admitted to four different south Indian hospitals for seizures. Once advised to avoid these oils, these patients saw a drastic improvement in their condition.
The research is one of the first to study the effects of these essential oils on seizures in adults and not just children, as previous research has looked at. Their findings were published in the journal Epilepsy Research.
To decipher whether convulsant essential oils are involved in first seizures or breakthrough seizures of patients with epilepsy and epilepsy syndromes, the researchers turned to four different hospitals. Throughout a period of four years, the researchers monitored people who entered these hospitals for their first seizure or a breakthrough seizure – a breakthrough seizure occurs after a person with epilepsy has not had a seizure for a long period of time. They were asked various questions, including whether they had taken essential oils recently, descriptions of the seizure, and any potential other medications they may be on.
The results showed that out of 350 patients, 55 (15.7 percent) had seizures associated with the use of essential oils – whether that be inhalation, ingestion, or topical use. These oil-related seizures were split further into subcategories: oil-induced seizures (EOIS), of which there were 22; and oil-provoked seizures (EOPS), of which there were 33. The most commonly implicated oils were those of eucalyptus and camphor, which are known to have pro-convulsant properties.
Whilst it is an extremely strong correlation, the authors state that further research is required before it is known for sure whether these essential oils are causative, or just associated with these seizures.
“The [essential oils] appear to be provoking these seizures but whether they are truly causative or associative must be clarified by further evidence from larger blinded studies,” state the authors within the paper.
“However, despite these limitations, [this study] is one of the largest studies on essential oil-related seizures in adults.”