Essential Oils: Helpful or Harmful?

*Disclaimer: I am not a registered dietitian, naturopath, doctor, or other type of healthcare professional. This is simply the product of my own research and opinions, not to be used to replace the recommendations of a registered healthcare professional.

Recently, essential oils have been quite the controversial topic. On one hand, like Frank’s Red Hot sauce, there’s an exponentially growing body of essential oil fanatics that literally “put that sh*t on everything”. On the other hand, there’s those that believe that, not only are essential oils a hoax, but they’re actually downright dangerous. So, whose right? Are essential oils helpful or harmful? Well, the answer is: kind of both.

Before we get into some of the literature about the uses and efficacy of essential oils, let’s first discuss what essential oils actually are. Essential oils are made by steaming or pressing various parts of a plant (ex. the bark, leaves, flowers or fruit) to capture the fragrance (or the “essence”) of the plant. This oil is very concentrated; and it takes several pounds of plant material in order to produce a single bottle of essential oil. Because there are over 100 different types of essential oils and enough information out there to write books on the subject, for the purposes of this post, I will focus on the use of some of the most popular essential oils for both skincare and aromatherapy. Then, I will dive into why essential oils have been causing such controversy and the argument for why they may be more bad than good.


Aromatherapy is the practice of using natural plant extracts (or essential oils) to improve both physical and emotional health. These essential oils can either be mixed with a carrier oil (to dilute it) and absorbed by the skin; or put in a diffuser to be taken up by the olfactory system (smelled). The most commonly used essential oils for aroma therapy include: lavender, eucalyptus, rosemary, chamomile and peppermint. Most research has focused on the use of aromatherapy to manage depression, anxiety, nausea, pain, sleep disturbances and muscle tension [1]. Some studies have even found that olfactory stimulation aromatherapy can cause an immediate reduction in pain, while also changing pulse, blood pressure, skin temperature and brain activity [2].

In a 2016 meta-analysis, researchers found that aromatherapy has a significant positive effect on pain reduction for a variety of conditions [3]. Aromatherapy was shown to be most beneficial for acute pain and nociceptive pain (i.e. post-operative pain, obstetric and gynecological pain), compared to inflammatory and chronic pain [3]. Additionally, the meta-analysis found that patients part of the aromatherapy group reported higher satisfaction with lower patient anxiety and depression [3]. However, it is unclear whether these emotional benefits were from the aromatherapy itself, or the extra attention the patient received while receiving the aromatherapy treatment (i.e. the act of massaging the oils into the skin) [3].

Aromatherapy has also been found to help improve and restore immune function. In a 2013 study on early stage colorectal cancer patients, it was found that after aromatherapy treatment with ginger essential oil 3 times per week, there was a significant increase in mean lymphocyte (immune cell) count; as well as significantly lower scores for symptoms such as fatigue, pain and stress, compared to the control group [4]. Another study on breast cancer patients also found a significant increase in lymphocytes and peripheral blood leukocytes (white blood cells) with aromatherapy treatment twice a week for 4 weeks using sweet orange, lavender and sandalwood essential oils [5].

Lastly, a 2017 study found that, when bergamot essential oil was diffused in the waiting room of a mental health treatment centre, there was an increase in positive affect (feelings) compared to the control group [6]. However, although this increase was not statistically significant, other studies using bergamot essential oil on patients with mild mental disorders have found significantly reduced blood pressure, heart rate, stress response, depression and anxiety - suggesting that bergamot essential oil may be a useful addition to the treatment of mental disorders [6]. Interestingly, another study on patients with depressive disorder found that olfactory stimulation with orange and bergamot essential oil resulted in significantly reduced dosages of antidepressants; as well as restoring stress-related immune reduction [7]. However, due to the study’s small sample size, more research is required to confirm the results.

Overall, the use of aromatherapy has shown to be an effective addition to the treatment of mental disorders, immunosuppressive diseases (like cancer); as well as pain management. Aromatherapy is also desirable because it is easy to administer and has very little risk of side effects. This lack of side effects is an attractive feature, as the medications administered to treat these above conditions can typically result in a multitude of adverse side effects.


One of the reasons that essential oils may be added to cosmetics is for fragrance, however research suggests that they also play a role as anti-microbial agents to treat a variety of skin conditions and infections. One essential oil that’s most common for its anti-microbial and mild anti-fungal activity is tea tree oil. In one 2007 study comparing treatment of 5% tea tree and 5% benzoyl peroxide on mild to moderate acne, it was found that both tea tree oil and benzoyl peroxide significantly improved the appearance of both inflamed and non-inflamed acne relative to the control group [8]. It’s relevant to note that the tea tree oil took longer for the effects to be observed, however the tea tree oil group experienced fewer side effects compared to the benzoyl peroxide group [8].

Another study investigating 5% tea tree oil on wound healing and circulation found that there was a significant increase in blood flow in the tea tree oil group compared to the control; and an increase in hemoglobin (red blood cells) and oxygenation [9]. These results are promising as the increase in circulation and blood oxygenation levels are crucial for wound healing.

I think it’s important to note that although the effects of essential oils relative to a control (a placebo) have been widely studied, still more research is required comparing the effects of essential oils to conventional treatments. Recently, one 2019 study found that, although certain essential oils do possess established antimicrobial activity, the effect is still significantly weaker than synthetic antimicrobials; including antibiotics [10]. The observed antimicrobial effects are found to be correlated with oils containing phenolic, aromatic or alcohol groups (i.e. tea tree oil, sage, eucalyptus, clove, cinnamon cajuput, thyme and lavender) [10].

But, despite this reduced efficacy, these essential oils still result in fewer adverse side effects and are still an effective all-natural option. Interestingly, it was found that majority of studies have shown that essential oils enhance the efficacy of conventional antimicrobials [11]. This is promising because, with the increasing problem of antibiotic resistance, essential oils are being further investigated for potential roles in conventional treatment; as microbes have found to be less resistant to essential oils compared to conventional antibiotics. Lastly, certain essential oils (i.e. lavender, thyme, peppermint, cinnamon, clove, eucalyptus and sage) have been found to also have antiviral activity, where conventional antibiotics do not serve any protection against viruses [10].

In terms of the use of essential oils in the cosmetic industry, one 2013 study investigating the anti-fungal effects of essential oils found that all tested essential oils (cinnamon, lavender, tea tree and paperbark) showed antimicrobial activity 1-3.5 times stronger than methylparaben (a common anti-fungal preservative used in cosmetics) at a concentration of 2.5% for essential oils and 0.4% for methyl paraben [12]. This may suggest the potential of replacing parabens with essential oils in cosmetics, which is huge considering that parabens have been associated with increased risk of cancer and hormone disruption. However, more research is required to confirm these effects within the formulation of a cosmetic product, as much more essential oil is required relative to the amount of paraben.

Overall, certain essential oils have been found to play an antimicrobial role against certain viruses, bacteria and fungi; which supports their efficacy in improving a variety of microbial related skin conditions and infections. Lastly, it’s important to note that increasing the concentration of essential oil is not the answer to producing a greater effect, as many of these oils can result in irritations, allergic reactions and even be toxic at high concentrations. Thus, if you are going to be using essential oils on the skin, they must be diluted with a carrier oil (like sweet almond, jojoba, coconut or grapeseed oil) to reach a lower concentration before application.

The Controversy

So, why are essential oils so controversial these days? A large reason for this has to do with the nature of how essential oils are produced. You can think of essential oils kind of like maple syrup. It takes several buckets of sap to make one bucket of maple syrup, which is why “100% pure” maple syrup is a lot more expensive and made in smaller quantities than what you would find in a grocery store. So, like maple syrup, the “100% pure” essential oils are going to be much more expensive and harder to find than the ones are cheaper and available at any grocery or drug store. So, if you see a whole kit of essential oils for under $20 and think you’re getting a good deal, your oils are most likely not pure.

However, even more expensive oils can be impure as well, which is why you should be aware of other factors, including: how the oils are packaged, the country of origin, the name on the bottle; and the presence of the Latin name. Firstly, you want to make sure that the oils are packaged in dark glass bottles for two reasons: 1) light oxidizes the oil and will cause it to go rancid; and 2) the oils will break down and leak through plastic.

Secondly, you want to know the country of origin (where the plant is grown) because quality can vary by country. Usually, essential oil brands will include the origin of where the essential oil was packaged, but not where the plant actually came from. This is important because, in a lot of cases, the type of plant written on the label was not actually the same plant used in the oil; but is instead a cheaper, more common version. Not only that, but the oil can then be diluted with cheaper oils, contain synthetic additives, synthetic fragrances, or be contaminated with pesticides and/or heavy metals from the growing and extracting process. These additives and impurities are usually a large part of why they can be so sensitizing to users, especially when used in skincare products. However, it’s important to keep in mind that these oils can still be sensitizing in their pure form - especially when used undiluted – due to their high concentration.

Lastly, you want to make sure that the name on the packaging says “essential oil” and not “fragrance oil” or “[insert plant] oil”; and the Latin name for the plant should be clearly stated on the bottle. For example, in the case of Lavender, there are multiple species of lavender, so having the Latin name will help identify which specific species has been used. Further, the term “therapeutic grade” is a marketing term and does not actually mean anything. If you are using an essential oil for a therapeutic property, it should have a Natural Product Number (NPN) from Health Canada. For example, tea tree oil sold for its antiseptic properties should have an NPN classifying it as an antiseptic. A good rule of thumb is, the more paperwork that is disclosed or can be supplied – in the form of specification sheets, third party testing and material safety data sheets (MSDS) – the better. It’s also a good idea to consult with a naturopath, trained herbalist or an aromatherapy practitioner for brand recommendations.

So, why is this happening? Is “Big Essential Oil” the next Big Pharma? Well, the biggest reason for the rise in essential oil fraud and adultery has to do with the exponentially growing demand for essential oils. Remember, essential oils require a huge amount of time and resources to produce. To put it simply, our demand for essential oils vastly outweighs their supply. Using synthetic additive and dilutions with other oils helps make a smaller amount of oil go a longer way.

Overall, I think that, as essential oils become more and more popular, more efforts should go towards their regulation within Canada and the US in order to ensure that consumers are actually getting what’s on the label. The reality is that, these issues are not exclusive to essential oils, but to other natural health products as well – especially supplements. Because these products are not classified as drugs, the company making the product is responsible for all safety and effectiveness testing before the product goes to market. Therefore, it is crucial that, if you are going to be using these products, that you do your research before making a purchase and, if accessible, get recommendations from a healthcare professional.

Do you use essential oils? Let me know in the comments!


[1] Boehm, K., Büssing, A., & Ostermann, T. (2012). Aromatherapy as an adjuvant treatment in cancer care--a descriptive systematic review. African journal of traditional, complementary, and alternative medicines : AJTCAM, 9(4), 503–518.

[2] Shin, B. C., & Lee, M. S. (2007). Effects of aromatherapy acupressure on hemiplegic shoulder pain and motor power in stroke patients: a pilot study. Journal of alternative and complementary medicine (New York, N.Y.), 13(2), 247–251.

[3] Lakhan, S. E., Sheafer, H., & Tepper, D. (2016). The Effectiveness of Aromatherapy in Reducing Pain: A Systematic Review and Meta-Analysis. Pain research and treatment, 2016, 8158693.

[4] Khiewkhern, S., Promthet, S., Sukprasert, A., Eunhpinitpong, W., & Bradshaw, P. (2013). Effectiveness of aromatherapy with light thai massage for cellular immunity improvement in colorectal cancer patients receiving chemotherapy. Asian Pacific journal of cancer prevention : APJCP, 14(6), 3903–3907.

[5] Imanishi, J., Kuriyama, H., Shigemori, I., Watanabe, S., Aihara, Y., Kita, M., Sawai, K., Nakajima, H., Yoshida, N., Kunisawa, M., Kawase, M., & Fukui, K. (2009). Anxiolytic effect of aromatherapy massage in patients with breast cancer. Evidence-based complementary and alternative medicine : eCAM, 6(1), 123–128.

[6] Han, X., Gibson, J., Eggett, D. L., & Parker, T. L. (2017). Bergamot (Citrus bergamia) Essential Oil Inhalation Improves Positive Feelings in the Waiting Room of a Mental Health Treatment Center: A Pilot Study. Phytotherapy research : PTR, 31(5), 812–816.

[7] Komori, T., Fujiwara, R., Tanida, M., Nomura, J., & Yokoyama, M. M. (1995). Effects of citrus fragrance on immune function and depressive states. Neuroimmunomodulation, 2(3), 174–180.

[8] Enshaieh, S., Jooya, A., Siadat, A. H., & Iraji, F. (2007). The efficacy of 5% topical tea tree oil gel in mild to moderate acne vulgaris: a randomized, double-blind placebo-controlled study. Indian journal of dermatology, venereology and leprology, 73(1), 22–25.

[9] Rothenberger, J., Krauss, S., Tschumi, C., Rahmanian-Schwarz, A., Schaller, H. E., & Held, M. (2016). The Effect of Polyhexanide, Octenidine Dihydrochloride, and Tea Tree Oil as Topical Antiseptic Agents on In Vivo Microcirculation of the Human Skin: A Noninvasive Quantitative Analysis. Wounds : a compendium of clinical research and practice, 28(10), 341–346.

[10] Wińska, K., Mączka, W., Łyczko, J., Grabarczyk, M., Czubaszek, A., & Szumny, A. (2019). Essential Oils as Antimicrobial Agents-Myth or Real Alternative?. Molecules (Basel, Switzerland), 24(11), 2130.

[11] Orchard, A., & van Vuuren, S. (2017). Commercial Essential Oils as Potential Antimicrobials to Treat Skin Diseases. Evidence-based complementary and alternative medicine : eCAM, 2017, 4517971.

[12] Herman, A., Herman, A. P., Domagalska, B. W., & Młynarczyk, A. (2013). Essential oils and herbal extracts as antimicrobial agents in cosmetic emulsion. Indian journal of microbiology, 53(2), 232–237.

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