“How do essential oils work?” They (usually) smell nice. They are all natural. They are fun to explore. But when it comes to medicinal actions, how do essential oils work is one of the most frequent questions we receive. It’s immediately after “Do essential oils work?” And it is such a good question to ask, especially if you are just starting to dive into aromatherapy. (Though it’s also good to ask even if you’ve been using them for many years!)
To complicate the issue, essential oils are unlike most other botanically-based medications and other conventional medications. They have three distinct methods of action, and when someone experiences aromatherapy benefits, it may not always be clear which mechanism is at work. Let’s take a look at the possibilities:
Method One: The Placebo Effect
Yes, that placebo effect. It’s not something aromatherapists like to talk about, but essential oils do work through the placebo effect. Before you close the page and write me off, keep in mind that anything can produce a placebo effect. Pharmaceuticals are used as placebos all the time (1). Medical doctors frequently prescribe antibiotics and sedatives as placebos for patients who don’t actually need medication.
The placebo effect, which is detailed in-depth elsewhere, merely refers to the powerful mind-body connection (2). This is the mechanism by which the mind is able to control physiological outcomes within the body. The placebo is a relatively new understanding, first applied to medical research shortly after World War 2 (3).
We now understand that all healing involves some level of placebo activity (4). To understand how something works, we must first account for how much of a substance’s effects are due to the placebo. If a person uses an essential oil and then experiences a positive outcome, we would be wrong to assume the outcome was due to the oil itself and not consider the potential for the placebo effect of the oil.
That’s why placebo controlled studies are considered to be stronger evidence than other types of research. To conduct this type of study, researchers measure how much improvement is found as a result of a placebo as well as how much improvement is found with the aromatherapy. How do essential oils work with the placebo effect? The effect that is above and beyond the placebo’s effects can be attributed to the essential oil. In other words, two mechanisms of action may be at play. Researchers must conduct statistical analyses to determine whether or not those added effects occurred due to chance or to the oil’s actions.
Method Two: The Olfactory System
This is the method that probably receives the most attention in the aromatherapy realm. Many schools of thought promote the idea that this is the only way that essential oils work. This method is exclusive to scent-based interventions because it relies on the volatile components of the essential oil evaporating in such a way that they can be inhaled into the body.
Unlike other inhaled medications, aromatherapy produces physiological effects in the body through the sense of smell. The sense of smell–aka the olfactory system–is powerful in humans (5). Additionally, the sense of smell has an elevated status among the human senses. This is seen by how the brain processes odors.
Most sensory experiences, such as sound, are sent to the thalamus, which relays sensory signals to the appropriate area, including the hippocampus and amygdala. Odors, however, bypass the thalamus and are sent to the olfactory bulb. This is also connected to the hippocampus and amygdala, which enables it to produce a stronger effect on memory and emotion (6).
Practically, this means that scent memory is specific and personal, not universal. Your scent memories are exclusive to you and your experiences. In aromatherapy, it means that an oil may be calming to me and irritating to you. How do essential oils work this way? These differences are due to the conscious or unconscious memories stored deep within our brains. Each of these memories are associated with the sensory experiences that accompanied the personal experience.
Scent memory works for inhaled oils that target subjective outcomes, such as pain, anxiety, and fatigue. Furthermore, this method isn’t exclusive to essential oils. The effects of scent memory can be triggered by anything aromatic, even synthetic fragrances or environmental aromas (7).
Method Three: Chemical Activity
Just like herbal medicines and pharmaceutical drugs, essential oils contain active chemicals. Many of these chemicals are able to produce medicinal effects when applied to the body in the correct dose. Chemicals such as menthol, eucalyptol, and limonene are responsible for many of the medicinal effects of aromatherapy (8, 9, 10). To take advantage of these actions, essential oils are often applied in potent topical preparations or through ingestion.
Essential oils for wound care, essential oils for cold sores, essentials for acne–all of these approaches rely on chemical effects of essential oils. An oil’s antiviral effects answer the question “do essential oils work for cold sores?” While an oil’s anti-inflammatory effects answer the question, “do essential oils work on bruises?”
Currently, much of the scientific study of the chemical activity of essential oils is conducted in a lab. These in-vitro and animal studies are useful for informing clinical research. However, they are not fully applicable to human health just yet. These findings must be tested in human clinical trials through clinical research on essential oils before they can be confirmed. That’s one of the priorities of the Franklin Health Research Foundation.
So… How do Essential Oils Work?
Essential oils work by one or more of three distinct methods of action. They are capable of producing a placebo effect. They also produce measurable effects in the body through the olfactory bulb. And they have powerful chemicals that produce medicinal effects on the human body.
When you inhale an essential oil or apply an oil topically, and you experience a health effect, it is worth exploring how you may have produced the effect. This inquisitive thinking enables you to replicate the effect again and again for both yourself and others. It also allows you to make oil, preparation, and dose selections more effectively.
So there you have it. The three major ways in which essential oils provide us with medicinal actions. Have more questions? Drop us an email or fill out the form to send me your questions. – Dr H
- Linde, K., Atmann, O., Meissner, K., Schneider, A., Meister, R., Kriston, L., & Werner, C. (2018). How often do general practitioners use placebos and non-specific interventions? Systematic review and meta-analysis of surveys. PloS one, 13(8), e0202211.
- Hashmi, J. A. (2018). Placebo Effect: Theory, Mechanisms and Teleological Roots. International review of neurobiology, 139, 233-253.
- Gensini, G. F., Conti, A. A., & Conti, A. (2005). Past and present of”what will please the lord”: an updated history of the concept of placebo. Minerva medica, 96(2), 121-124.
- Kaptchuk, T. J., & Miller, F. G. (2015). Placebo effects in medicine. New England Journal of Medicine, 373(1), 8-9.
- McGann, J. P. (2017). Poor human olfaction is a 19th-century myth. Science, 356(6338), eaam7263.
- Phelps, E. A. (2004). Human emotion and memory: interactions of the amygdala and hippocampal complex. Current opinion in neurobiology, 14(2), 198-202.
- Reid, C. A., Green, J. D., Wildschut, T., & Sedikides, C. (2015). Scent-evoked nostalgia. Memory, 23(2), 157-166.
- A Farco, J., & Grundmann, O. (2013). Menthol-pharmacology of an important naturally medicinal “cool”. Mini reviews in medicinal chemistry, 13(1), 124-131.
- Seol, G. H., & Kim, K. Y. (2016). Eucalyptol and its role in chronic diseases. In Drug Discovery from Mother Nature (pp. 389-398). Springer, Cham.
- Sun, J. (2007). D-Limonene: safety and clinical applications. Alternative Medicine Review, 12(3), 259.