I'm a Certified Massage Therapist and, I'll be frank, this Essential Oil craze has me worried. Don't get me wrong, I love essential oils and I use them when I do massage or Reflexology. They really do help ease sore muscles, relieve swollen or inflamed tissue, and help with a myriad of health problems. However, in almost all cases, essential oils need to be used with the help of someone trained in their use.
As a Massage Therapist, I have a nominal amount of training so that I can use the oils that will assist the people I work on in relaxing and/or healing their muscles/tendons. But! If you want to use EOs for holistic health reasons you need to do one of two things; 1) go to a Nationally Certified Aromatherapist, or 2) research, research, research before using any oils in any amount in any way. Some oils can cause seizures if you happen to be prone to those. Children under a certain age should not have EOs used on them. You also need to let your physician know if you're using EOs (same as when you use over-the-counter supplements) because some oils might react badly with some medication. That's not to say don't take doctor prescribed medication, that's simply a caution. Doctors need this information the same as they need your medication information. Remember, medications can sometimes interact badly with each other, too.
I'm also leery of any site that promotes their oils as "Therapeutic Grade" because, if you have a good company selling as pure a product as there is, it's all "therapeutic grade", you can't get any better than "100% pure peppermint oil" (or whichever oil you're considering). And, please, be wary of those who make claims of being able to "cure" or "fix" whatever problems you have. Oils do NOT cure anything! They are a supplement or an aide to whatever is going on with you at that time. Sometimes, prescribed medication, alone, is not enough. Perhaps you need the assistance of an Acupuncturist. Please, tell me you wouldn't be insane enough to try this on yourself (unless you happen to be a trained Acupuncturist). Holistic medicine, when it's done by certified, conscientious professionals, works hand-in-hand with your doctor(s).
Here are a few facts about Certified Aromatherapists:
1) Certified Aromatherapists are required to study chemistry, same as any doctor or nurse, so they know how certain oils will act and react together and to prescribed medications. If they're not sure, they will advise you to check with your doctor or get your permission to speak with him/her themselves. ANYone who tells you that you don't need to check with your doctor, or tell him/her about the oils you're using, is hiding something. Or, to put it another way, they're an Old Fashioned Snake Oil Salesman!
2) They want to work with your doctor (see above) because they want you healthy. They may even give you a simple recipe for spraying around the house during cold season to help combat those nasty cold germs! (you can find those recipes on-line, as well but, again, be aware of the oils and, if you have kids under a certain age - which will be noted - don't use them)
3) They never make claims that they can cure or fix something that your doctor cannot nor do they make claims that they can tell you have this or that health problem but, don't bother checking with your doctor on it because no medical tests will be able to detect it (it's in the pre-diagnostic stages!) and to attempt such a test might trigger the condition to explode into full blown (fill in your favorite disease here). Again, can you say Snake Oil Salesman?
4) Aromatherapists tailor their oil solutions to each individual. I'm not saying there aren't recipes for certain things (i.e., the oils I use for massage are usually 3 drops of this and 5 drops of that and 2 drops of the other thing in a carrier oil solution) but, holistically speaking, there's no one "off the rack" solution for every health dilemma. And, again, you don't want the oils you're using to react negatively with any prescribed medications. If you're working with an Aromatherapist for, say, depression, he/she is going to tailor their suggested blend to work with where you are, emotionally as well as medically, then monitor you to see if changes need to be made to the blend. What would work for me won't necessarily work for you.
5) NO reputable Aromatherapist is going to tell you to take oils internally for any reason. At least, not without closely monitoring you. I've used peppermint oil on my gums when I've had an ache in a tooth or my jaw, I've even used it - sparingly - under an Aromatherapist's advisement for stomach troubles, and I've used a few oils as a mouthwash (but I spit that out, not swallow it!), but I would NEVER even dream of swallowing EOs due to their natures. If you can't put it directly on your skin without diluting it in a carrier oil (and they will tell you they should ALL be diluted!) why would you put it in your stomach!?
Finally, folks, I can only say once more - research, research, research! Just because something is suddenly popular doesn't mean those promoting it know what they're talking about. My best suggestion is to find an Aromatherapist who would be willing to answer your questions (they all would, by the way) but, if you're not sure where to start, go to the web site for the National Association for Holistic Aromatherapy (here) or the Aromatherapy Registration Council (here). They'll be glad to either answer your questions or put you in touch with a Certified Aromatherapist. Please, the best defense to your health is YOUR continued education.