Lately, I’ve had several people ask me what the big deal is about essential oils, whether they actually work, and (if they do actually work) how exactly they work. Some people hear about essential oils from friends or family, but may be skeptical because their doctor doesn’t recommend using them and says they are a “quack” remedy. Others may see the benefits of essential oils but want to know how to tell their friends and family about the benefits without seeming like they are snake oil salesmen.
The first thing I want to make clear is that the efficacy of any essential oil/aromatherapy depends on how it is being applied and for what reason it is being used, as well as the quality of the oil itself. (For instance, you don’t want to mistake lavender-scented oil for lavender essential oil, as they are two vastly different things.) If you want wound healing, it would be unwise to apply an essential oil that has properties that are generally irritating to the skin, such as Cassia or Lemongrass. If you are looking to relax someone, using an oil that is known to stimulate the nervous system (such as Oregano or Basil) is going to be counterproductive. However, when essential oils are used properly and within a reasonable spectrum to assist someone medically, then, yes, they can be very effective and “actually work.”
There are multiple ways in which aromatherapy can be applied. The most common, for obvious reasons because of the name, is via inhalation of the oils. Essential oils affect the limbic system of the brain, which is responsible for memory and emotion. This is why smelling grandma's soup recipe can create warm and fuzzy emotions, whereas smelling something with which you associate a negative experience can trigger the opposite emotional reaction.
Another common way to apply essential oils is via direct application through massage oils, creams, gels, or even neat (undiluted) in rare cases. This allows the oils to be directly absorbed into the bloodstream so that, in addition to acting on the limbic system of the brain, they can provide other direct physical benefits, such as increased circulation, relief from muscle soreness, wound healing, etc. There are even some studies that have shown promise with certain essential oils (oregano being the top one that comes to mind) being used in the future to help combat cancer, if they can figure out how to deliver it.
How do essential oils accomplish all of this? It's a receptor-driven response. Much like how pharmaceuticals work by attaching to chemoreceptors on your cells to trigger a certain reaction from your body (or mind, in the case of psychological drugs), essential oils work in exactly the same way. They're kind of a "natural" drug, if you will. Essential oil molecules are readily absorbed by the olfactory epithelium (because they are lipophilic substances). Once that scent is registered by the chemoreceptors, a nerve impulse is generated and passed into the olfactory bulb. That nerve impulse travels up the olfactory tract and the interpretation of the scent is shown by the response of the limbic system, which includes the amygdala, hypothalamus, and hippocampus, among other sections associated with memory, instinct, and emotional responses. Certain chemicals cause the brain to produce hard-wired responses.
Essential oils are incredibly complex, chemically speaking. Depending on the oil, they can contain monoterpenes, such as limonene, myrcene, alpha-pinene, beta-pinene, beta-ocimene, delta-limonene, and others (found in the citrus fruit oils, pines, basil, and lemongrass species); sesquiterpenes, such as bisabolene, beta-cadinene, chamazulene, alpha-cedrene, alpha-curcumene, alpha-farnesene, beta-santalene, and others (found in German Chamomile, Myrrh, Juniper, Yarrow, Wormwood, Cedarwood, Ginger, Rose, and Sandalwood); monoterpene and sesquiterpene alcohols (I'll stop listing individual examples since that takes up a lot of typing, but you get the idea); phenols; phenylpropanoids; esters; aldehydes; ketones; oxides; sesquiterpene lactones; and coumarins.
Several essential oils have also been shown in scientific studies to have potent antibacterial properties, especially when they are mixed together. Here are several scientific studies showing various methods of application and benefits of essential oils:
As well as two studies demonstrating the efficacy of essential oils against MRSA:
Now, an important thing to note is that, while these oils generally produce natural emotional and physiological responses in the brain and body, those responses can be corrupted by negative experiences that occurred while those scents were present. Let's say that a young woman was sexually assaulted multiple times by a man whose cologne had a strong element of Patchouli essential oil. While Patchouli is normally very relaxing due to its earthy nature (and is even considered to be an aphrodisiac, depending on how you define that term), this particular young woman would probably never be able to smell Patchouli again without extreme feelings of fear or revulsion, along with a whole host of other emotions unique to her personality and level of healing from such an experience. So, even the natural bodily response to smelling essential oils is only so powerful. However, generally speaking, the limbic system will respond to the chemicals within the essential oils in the way that the chemicals naturally cause the body to react. For instance, esters are known to be anti-inflammatory and relaxing, so a diffusion of an essential oil that is high in esters (lavender, bergamot, clary sage, petitgrain, and neroli, for instance, which all have linalyl acetate, among other chemicals) will yield a calming result.
Here's where most people get hung up (and why I deplore companies like doTerra and Young Living which advocate unsafe practices or don’t train their representatives on proper use of essential oils). Essential oils are incredibly potent. If you look at some of the scientific articles about using essential oils as antibiotics, you'll see that they found extremely low concentrations were effective. This is because the oils are the concentrated products of tens, hundreds, or even thousands of plants, depending on the oil. It takes 2000-4000 kg of rose petals to produce just 1 kg of the essential oil (4400–8800 pounds to yield just a little over 2 pounds). One drop of peppermint oil is equivalent to around twenty to thirty cups of the tea made from the leaves. So you really don't need much, and because they are so potent they should never be used internally without the oversight of a certified aromatherapist, as some of them can cause kidney and liver damage. Even having the scent of an oil in the room at a subliminal level has been shown to influence the mind and body of whoever was exposed to it.
If you are looking to apply it to the body, almost all oils need to be extremely diluted in a vegetable oil carrier (we're talking 2.5% to 5% concentration maximum, and even less than that for children and the elderly) to prevent causing chemical burns to the skin. So, a one-ounce blend of oils would have no more than fifteen drops of essential oils total in one ounce of carrier oil. In rare cases, such as short-term therapeutic use (a muscle strain or tear, for instance) a concentration as high as 30-50% can be used, but a patch test is always a good precaution in such cases to make sure that the recipient is not going to experience a sensitization reaction. (Patch tests are always a good idea for any dilution, actually, but are especially important the higher you get on the dilution scale.)
Fortunately, essential oils are starting to gain the positive attention of doctors of Western medicine, thanks largely to both the scientific studies done that show their efficacy as well as the success stories that their own (responsible) patients tell them. Sadly, there are still plenty of doctors out there who are extremely averse to use of essential oils -- or any form of alternative medicine for that matter -- because they've either never been shown how effective it can be or they have seen it misused. (e.g. Seeing chemical burns on someone who used an essential oil improperly, or watching someone with cancer opt for no stronger treatment than a drop of oregano oil with each meal.) However, it can be hoped that, as more people educate themselves on how essential oils actually work and use them properly to support their health in responsible ways, that more doctors and health professionals in general will come to recognize their significant benefits and efficacy.