I’ll make this blog post short as I want a few sentences to have a great impact!
Please please please do not use essential oils neat on the skin or ingest – long term usage in this way will almost certainly produce an adverse reaction.
Don’t listen to anyone who tells you that their essential oils are Food grade and therefore ok to ingest or a “Therapeutic grade” pure enough to be applied neat to the skin. If you want to take the risk of applying them neat to your skin you could provoke an allergic reaction at any point. Why put yourself at risk when diluting them is a far safer way and you don’t lose any of the benefits?!
This blog post from Robert Tisserand explains very clearly what happens and why this method of essential oil use should be avoided. It is specifically written about the topical use of cinnamon oil, however the last few paragraphs very clearly state the dangers of not diluting essential oils.