The Case for an Evidence-based Aromatherapy Practice – Tisserand Institute

The current mood around aromatherapy is complex. There are companies and company representatives making ludicrous health claims which are damaging to the reputation and therefore the development of the practice. In contrast, there are the vocal cynics and critics who, using mostly offensive, ignorant language, insinuate that all complementary and alternative medicine (CAM) practice is sham, there is no evidence that it works (a very broad statement), those who practice it are quacks, and those who research it are pseudoscientists. Finally, there are practitioners who strongly support research, and then there are those who don’t. In between, some agree a little, but they do not necessarily trust the intentions of the people who conduct the research. This is the climate we are all operating in. For some, none of this may matter, but for me it is a personal challenge!

Anecdote provides a strong narrative that people can relate to, and this makes it difficult to set aside when we are thinking about evidence for practice. Often, anecdotal evidence is the starting point to much larger research studies and so it is not completely discounted, and it is why it does make an appearance in the hierarchy of evidence. However, the case study is not enough evidence on which to base clinical decision making.

Think about it like this – you might hear someone say, “my grandmother died at the age of 96, with a cigarette in her hand; she didn’t die of cancer”. Does this one experience suggest that there is no link between smoking and lung cancer? Even if you heard this half a dozen times throughout your life, from different people, would you be encouraged to go and pick up a cigarette? Probably not, because these individual stories are just that, unique experiences. Hard evidence, whilst often very dry and sometimes difficult to comprehend, tells us a very different story.

There are a number of terms we use in clinical research that help to identify why anecdote is not the most reliable form of evidence. For example, we talk about regression to the mean –that everything will even out over time, with or without intervention (Barnett et al., 2004). For example, we might apply an essential oil to treat someone experiencing cold symptoms. It is difficult to say that this person was “cured” based on the treatment, because the cold symptoms would have naturally resolved with time. It may even be difficult to claim that treatment alleviated some of the symptoms, because the client may not have reported using cold medicine or other forms of cold remedy.

In research, bias means “a deviation from the truth” (Simundić, 2013). Anecdotal evidence is subject to a number of different types of bias including selection bias, confirmation bias and evaluation bias. The introduction of any bias in any research limits the amount of trust the reader can place in the results.

Tamara AgnewTamara Agnew holds a PhD from the University of South Australia following her study on the effect of essential oils and aromatherapy on the physical and psychosocial symptoms of acne vulgaris. She is a lecturer at the University where she teaches research methods, Global National Health and First People’s Health, and she is a […]

Source: The Case for an Evidence-based Aromatherapy Practice – Tisserand Institute

Do we need more research?

There is a paucity of good clinical research in the fields of aromatherapy and essential oil research, and the primary reason for this is the lack of funding for such research. There are some studies claiming efficacy, however they are often methodologically flawed (Vickers, 2000, Agnew et al., 2014), meaning that the research design does not support the results. Studies are often subject to bias because they are under powered (there are not enough participants in the study to infer that something worked), or there are issues with the methodology. There is a catalogue of bias that can limit the results of apparently strong clinical research. It is important to highlight here that if the research is not methodologically sound, then the results are not automatically trustworthy.

Good clinical research is a prospective investigation to explore the effect of a treatment or intervention, which allows researchers to measure clinical effect using validated instruments. The publication of a study protocol holds researchers to account, meaning they cannot stray from their plan, without having to be transparent about the deviation. The design of clinical research is all about rigor – everything must be transparent so the reader can determine the quality of the research, and whether the findings can or should be implemented into their practice.

There are some very well-designed studies reporting positive outcomes. It is not all doom and gloom! For example, a recent meta-analysis reported on the effect of enteric coated peppermint oil on global symptoms and abdominal pain associated with IBS (Alammar et al., 2019). While they highlight some areas of concern, including attrition bias (excessive loss of participants without any explanation in one study) and bias related to the industry funding for research (that the published research is conducted by a stakeholder with a vested interest in the outcome in one study), the authors are confident that these generally well-designed studies prove that peppermint oil is an efficacious treatment for the symptoms of IBS.


There is a now need for aromatherapists to adjust their attitudes towards science, and overhaul approaches to practice. Aromatherapy (along with many other CAM practices) now needs to move away from expert-based to evidence-based practice. While it may not be the popular opinion, developing a strong evidence base, and applying this in the clinical setting, will help to promote aromatherapy as a reliable, rigorous, viable, accessible therapeutic intervention, rather than one that dwells on the fringes of healthcare, and is subject to biased and redundant criticism.

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