Essential oils are concentrated extracted plant chemicals that have a strong smell of the plant they were extracted from - their "essence". These oils are often heated in a diffuser, or evaporated via a wick, in order to spread their smell. Of course, if nice smells were all these oils were about, there wouldn’t be much for me to be skeptical about.

However, an entire branch of pseudoscience has built up around essential oils - aromatherapy. Not happy with the joy they can bring from hiding the smells of dog hair and mould, some people claim that these smells can help treat medical conditions. I will accept that peppermint or eucalyptus can help to clear a blocked nose, but the idea that you can heal cuts, cure dandruff, ease your joint pain or boost your libido with flower smells is just plain silly (and all of those claims came from a major online "health" shop in NZ).

Sadly, attached to these claims we sometimes see another layer of skullduggery that’s of interest to skeptics - the dreaded Multi Level Marketing scheme. This is the case with doTERRA, an MLM that has recently found a footing in New Zealand. I’ve chatted with doTERRA sellers at several trade fairs (often called Mind, Body, Spirit festivals), and have been appalled by the level of unsupported medical claims they were happy to make, and the hollow promises of riches if you join their the pyramid shaped business structure somewhere near the bottom. Having said that, I usually walk away from the doTERRA stand smelling fantastic.

Now, thanks to a recent study (opens new window) into essential oils published in the journal Epilepsy Research, we know that they may be responsible for causing seizures in some people who use them. An analysis of 350 cases of seizure patients admitted to four Indian hospitals found that 55 of them were related to use of camphor or eucalyptus essential oils. Of these, 40% had never even had a seizure before.

The authors, as is often the case, are calling for more work to be done to study the potential effects of essential oils on the people who use them regularly, and suggest that doctors might want to start enquiring about essential oil use in those who present with seizures - especially those who suffer a "breakthrough" or first seizure.

For now, given the lack of evidence that essential oils do what they’re claimed to do, and the risk of seizures, I’d recommend that people stick to using them to make their bathroom smell nice. Also, don’t pay for supposedly superior products that come from a Multi Level Marketing scheme - you’re likely not paying extra for any healing properties, you’re just sending your money up a chain of "independent consultants" that reaches all the way back to the US. And those consultants all take a chunk of money in return for having convinced unwary people to join them in a scheme that has a more than 90% chance of losing them money.