When I see a client, I process a lot of information about the physical state of the client, where they are emotionally, their own preferences for different oils etc. There are a number of scientific studies that look at the effectiveness of different oils for various conditions. Rosemary and Vetiver for instance both have some evidence t back their use in ADHD. Other oils have some research backing for use in anxiety. Many have evidence that they can destroy bacteria or viruses in the lab though their effectiveness in treating systemic infections is less well documented. Perhaps the most important scientific data is that on essential oil safety and contraindications for various oils. At least using that we can follow the dictum, “Do no harm!”
On top of that there is of course a vast body of anecdotal evidence. Sadly much of what is taught in aromatherapy training schools does not have more than this anecdotal evidence to back it up. Yes there is a lot of this evidence. Every practitioner builds up masses of it and often shares this in formal or informal ways – case studies and chatting to colleagues both come to mind.
When I trained, I did a lot of my case studies at an in-patient adolescent mental health unit and went on to treat about another 40-50 clients there before I left. While a significant number of those I treated rated this as a really important part of their treatment and something that really helped them, a large part of this was the psychological effects of receiving touch in a safe environment and while I have knowledge of the oils used, it will never be the sort of evidence that will be accepted by the scientific community.
So, when treating clients, I use a combination of the limited scientific evidence there is along with a combination of what I was taught during my training, my reading of aromatherapy text books since then and my gut feeling of which oils are most likely to work, taking into account any feelings a client has about an oil. For those with depression I often let them smell both Bitter Orange and Bergamot and choose between them. (About 60% choose Bergamot but I need a few more clients before I can claim statistical significance for this!) I was also amused and saw it as a positive sign when a client recently described this process as like going to the optician!
I also think it important that I try and work out the reasons behind my gut feelings when I think a particular oil is the one to choose from over 60 in the boxes I carry. Just as when I was working more in psychotherapy gut feelings are often based on knowledge that is out of awareness and by spending time tracking this down we are able to expand our knowledge and perhaps even more importantly pass it on. If enough practitioners report similar anecdotes, eventually this can lead to clinical studies being done.
Before we can call ourselves a scientific discipline a lot more evidence needs to be gathered, published, challenged and refined.