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As a public health researcher, I’d be remiss to say that every study in the medical literature represents accurate data and essential oil science is no exception – the studies have to be studied sometimes!

Somehow, researchers with poorly designed studies or alternative motives got their articles published by reputable and sometimes not-so-reputable journals and the blogosphere is filled with confusion and essential oil myths, including essential oils scientific evidence.

Examining Essential Oil Studies

Out of the thousands of peer reviewed studies I have reviewed, I have observed that a majority of studies misrepresenting essential oils did so to downplay their therapeutic effect(s); not inflate them to sensationalize some unsubstantiated healing claim. However, there are always exceptions to the rule and I’ll begin with the most well-known one: Boswellic acids in frankincense essential oil.

This post, therefore, is an attempt at:

  1. Busting common essential oil myths about essential oils scientific evidence in the medical literature.
  2. Itemizing a growing collection of bad essential oils scientific evidence studies.
  3. Providing logical, evidenced-based rebuttals to the false conclusions and data points that these misleading studies draw.
  4. Helping clear up the confusion on Google and create trusted essential oils scientific evidence for bloggers and health care practitioners.

Please note that this article is not static. It’s a growing collection of bad essential oils scientific evidence and tips on how to sniff them out, and I will update this post as I continue to do research. If you’d like to share some bad essential oils scientific evidence, please leave the URL in the comment section below and let’s make this a team effort!

Sniffing Out Poor Studies

Whether or not you are a novice EO user or an advanced practitioner in aromatic medicine, it’s important that you tread the medical literature lightly or else you could be found guilty of not only spreading essential oil myths, but in providing dangerous, ineffective advice!


Because published research studies that discuss the therapeutic effects and safety concerns of essential oils scientific evidence can be misleading and many of them cannot be taken at face value. This has caused literally thousands of well-intentioned bloggers and health care practitioners to fall down a slippery slope as they discuss their essential oils scientific evidence findings from

I’ll confess, I was one of those novice essential oil researchers not too long ago. Thankfully, some friendly aromatherapists like the founder of the Atlantic Institute of Aromatherapy, Sylla Sheppard-Hanger, went out of their way to notify me of my mistakes.

I quickly realized that the public health background didn’t cut it and that I needed more formal training in aromatherapy to ensure that I accurately reported the truth about essential oils scientific evidence in my interviews, articles and books. Since then, I’ve edited (and continue to update) my articles and books and will not stop as my understanding of aromatherapy develops as my essential oils scientific evidence peels off layer by layer of this all-too-mysterious healing art.

NOT ALL STUDIES ARE CREATED EQUAL So, how do you sniff out the bad essential oil myths regarding essential oils scientific evidence?

Unfortunately, it’s not an easy answer. It requires a thorough understanding of essential oil chemistry and advanced research concepts like epidemiology and biostatistics to be really good at it.

Instead of telling you to “leave it to the pros,” I’d rather empower you to DIY with some trusty tips. But be careful. You can get yourself in trouble really quick and there are serious safely and therapeutic ramifications if you used these precious plant-based compounds incorrectly.

To help you on your journey, here are six guidelines to remember:

  1. Extracts are NOT essential oils. Unlike essential oils, extracts contain volatile and non-volatile components. This means that the chemical constituency and, therefore, the safety consideration and therapeutic effects are quite different.  Because of language barriers (many EO studies are done oversees) and simple ignorance, many studies evaluate extracts but call them essential oils in their articles. A common trend I’ve noticed is that these articles use the words “extracts” and “essential oils” interchangeably. I’ll point out some key ones below.
  2. Isolated chemical constituents are NOT essential oils. Putting things into context is important. Far too many studies draw from therapeutic and safety conclusions based on one or two chemical constituents that make up the essential oils that are being discussed in the article. Yes, each chemical that makes up an essential oil can determine safety and therapeutic efficacy to a large degree, but it is still only one of sometimes 200+ chemicals and is not an isolated compound. The bottom line is that we need to be careful about misleading conclusions based off of constituent studies.
  3. Human studies are rare.  It’s important to remember that a vast majority of essential oils scientific evidence is either in vitro (cells in a petri dish) or animal studies. Relatively few trials have been conducted on humans. This is not to invalidate these studies, but (like isolated chemical constituent studies) to put things into proper context. Beware of research studies that draw from conclusions based off of non-human research.
  4. Abstracts can be misleading. This is a tough one for people to understand, but an abstract is not a research study. It’s a snap-shot and oftentimes lacks key data points and contextual information. The solution is to read the entire article, which I understand is not always possible because many studies are pay-to-read. If you cannot find a free version, then do NOT base a firm conclusion off of the abstract until you read the entire report to make sure everything lines up.
  5. Research & researchers are not infallible. Just because something is “peer-reviewed” doesn’t mean it’s 100% correct. And don’t forget that researchers are people. Simple, prone-to-mistake people, just like you and I. Errors abound in the medical literature and we need to do our best to find them out.
  6. Author bias. Do a quick search of the author to find out if there is any financial bias. PubMed makes this super easy and will tell you if they represent an organization that has ties to a particular brand or company.

Debunking 3 Common Myths

Remember, this is a growing collection of bad essential oils scientific evidence and if you’d like to share some studies, please leave the URL in the comment section below and let’s make this a team effort!

1.  Boswellic Acids in Frankincense Oil

Article Title: Boswellia sacra essential oil induces tumor cell-specific apoptosis and suppresses tumor aggressiveness in cultured human breast cancer cells.

  • “More abundant high molecular weight compounds, including boswellic acids, were present in Boswellia sacra essential oil prepared at 100 oC hydrodistillation.”

Article Title: Differential effects of selective frankincense (Ru Xiang) essential oil versus non-selective sandalwood (Tan Xiang) essential oil on cultured bladder cancer cells: a microarray and bioinformatics study.


This was a tricky one for me. When I first started to report on essential oils, I was assigned the task to discuss how frankincense essential oils could possibly attenuate cancer cells. Being the public health researcher that I am, I followed my normal course of action and conducted a thorough literature review. When these two studies came up from the journal BMC Complement Alternative Medicine, I didn’t think because I have used their resources before and they always seemed to be legitimate.

DON’T BE FOOLED Not being a chemist, I was initially misled by this study and took these results at face value.

As any chemist will tell you, however, the molecular weight of boswellic acid is too heavy for it to be included in the chemical cornucopia of what we fondly refer to as essential oils because they are not volatile. Remember, essential oils are the volatile organic compounds extracted from the steam distillation process. Meaning, they are low weight and readily evaporate.

This should be common knowledge in the essential oil community, and even Wikipedia puts it this way, “While boswellic acids are a major component of the resin the steam or hydro distilled frankincense essential oil does not contain any boswellic acid as these components are non-volatile and too large to come over in the steam distillation process (the essential oil is composed mainly of the much lighter monoterpene and sesquiterpene molecules with small amounts of diterpenoid components being the upper limit in terms of molecular weight).”

Why is this important? Because frankincense is widely touted for its anti-tumor, cancer-fighting prowess and a myth has developed that it is because of the supposed boswellic acids that are contained in the essential oil. Subsequently, you’d want to supplement with Boswellia resins (not frankincense essential oil) if you’re trying to benefit from the cancer-fighting properties of boswellic acid. This is why specific boswellic acid supplements have been formulated to help people boost their immunity, reduce their risk of various inflammatory disease!

To summarize, quoting chemist Dr. Robert Pappas, “If there is any Boswellic acid in any true water distilled or steam distilled frankincense oil it’s a miniscule amount and it’s not going to be in there as a result of the molecule being actually distilled, but would have to be by some secondary process, perhaps from harsh stirring or spattering that goes on during the distillation process because the resin is typically vigorously stirred during the entire distillation.  However any trace amount may have gotten in there, let’s be clear on this,  the molecule itself is not volatilizing and then recondensing like all essential oil molecules must be able to do during a typical distillation process.”

Does this mean that frankincense is not helpful against cancer. No, not at all!

The jury is still out as to the exact mechanism(s) explaining why frankincense essential oil is so beneficial to cancer patients. However, advances in recent research suggest that Beta-elemene – a cancer fighting terpene found in frankincense and myrrh with the ability to cross the blood brain barrier – may be partly responsible.

As stated by the Memorial Sloan Kettering Cancer Center, “Beta-elemene is a compound found in plants such as celery, mint, and in many others used in traditional medicine. Although the pure form is not used as dietary supplement, some cancer patients use herbs high in beta-elemene as treatment. Beta-elemene was shown to prevent growth of cancer cells in laboratory cells by different mechanisms. A few poorly designed studies done in humans showed that it may improve quality of life in cancer patients. It is unclear if raw herbs containing beta-elemene have the same effects in humans. More research is needed.”

Some even suggest that the amount of β-elemene that frankincense and myrrh contain could very well explain why so many people claim that both oils have been instrumental to them Beating Cancer God’s Way.

At the end of the day, once we know the basic properties of an herb, root and resin we are able to determine the best ways to utilize it.

Article Title: Frankincense oil derived from Boswellia carteri induces tumor cell specific cytotoxicity.

  • “In search of the active medicinal ingredients of frankincense resins, Chevrier et al. reported that ethanol extract of Boswellia carteri resin comprises 7 boswellic acids. Akihisa et al. reported that methanol extract of Boswellia carteri resin consists of 15 triterpene acids, including boswellic acids, and 2 cembrane-type diterpenes.”

Article Title: Differential effects of selective frankincense (Ru Xiang) essential oil versus non-selective sandalwood (Tan Xiang) essential oil on cultured bladder cancer cells: a microarray and bioinformatics study.


This is an easy one. Trying to explain the tumor inducing found in frankincense oil, researchers mistakenly fell into the trap of comparing apples to oranges. Read the titles and quotes above carefully. Note the title refers to frankincense “oil,” but the study is actually about “extracts.” See the difference?

At first glance, it’s super easy to misquote these studies, which is why you need to read the entire article and not just the abstract!

2.  Lavender Causes Breast Growth in Boys

Article Title: Prepubertal Gynecomastia Linked to Lavender and Tea Tree Oils.

  • “The patient’s mother reported applying a compounded “healing balm” containing lavender oil to his skin starting shortly before the initial presentation.”


The long and the short of it is that three boys obscurely developed idiopathic cases of prepubertal gynecomastia (when boys experience enlarged, tender breast buds) for a short period of time (1 – 5 months).

It was determined that all three patients were using either a shampoo, lotion, soap or balm that included lavender oil and Melaleuca alternifolia (tea tree) oil as ingredients. The researchers extrapolated that these essential oils were “estrogenic” based off of a preliminary in vitro evaluation. In their words, “On the basis of the three case reports and the in vitro studies, we suspect that repeated topical application of over-the-counter products containing lavender oil or tea tree oil was the cause of gynecomastia in the three patients.”

There are several epidemiological reasons why this conclusion is false and is out of the scope of this article to cover each one, but I’ll leave you with this thought: just because lavender and tea tree oils were two common ingredients in the products that these three boys were using does not prove that they were the cause!

This is a classic statistics blunder that many make. “Correlation does not imply causation,” because there are countless other variables that are not being considered (diet, environmental triggers, medicines, and etc.).

Suffice it to say that essential oils safety expert Robert Tisserand emphatically states that, “Lavender oil does not mimic estrogen nor does it enhance the body’s own estrogens.

It is therefore not a ‘hormone disruptor’, cannot cause breast growth in young boys (or girls of any age), and is safe to use by anyone at risk for estrogen-dependent cancer.” And Tisserand’s conclusion has been supported by more recent research.

In 2013, for instance, the International Journal of Toxicology published a study confirming that lavender is not estrogenic, at least in female rats. Whether it is for humans remains to be seen, but there is literally no research to prove otherwise.

Essential Oils - Scientific Evidence and Unsafe Myths

3. Lavender & Rosemary Oil “Don’t Work”

Article Title: No effects of rosemary and lavender essential oil and a placebo pill on sustained attention, alertness, and heart rate.

  • “Essential oils (EOs) are widely used for various purposes, however, their claimed effects are often not supported by empirical data.”


This one is a doozy, and I’ll try to be nice. 😉

My gut instinct tells me that these researchers are quite heavily biased against EOs and put together a bunk study to prove their point. The first sentence in the abstract states, “Essential oils (EOs) are widely used for various purposes, however, their claimed effects are often not supported by empirical data…”

Here are some of the problems with the study.

The researchers attached an expectation to the placebo – telling people that they would receive a pill containing rapidly absorbed substances of herbal origin that would improve their alertness. Because they did not give the same disclaimer with essential oils, this negates the entire placebo experiment. Still, inhaling EOs performed similarly to the anticipation loaded placebo, which suggests that the EOs performed as we’d expect them to! Yay for EOs! 😉

The key here is essential oil “dosage.”

1) There is a huge difference between therapeutic dosage and “perceived” smell, which is what they tested for.

2) Simply spraying an EO once in a room is not the typical approach to aromatherapy treatment.

3) We are not told how far people were from the experimenter who was spraying the EO and whether or not they could actually smell the EOs.

4) In fact, the amount they used was exceptionally substandard. “Oils were sprayed in the room of the experiment with a dosage of 1 drop (appr. 20 mg) per 1 m3 of air,” cannot even compare to our gold standard studies that test 10, 225, and 450 mg/m3 after 20 minutes of exposure!

To have a pill as a placebo to compared against inhaled EOs also doesn’t make any sense further negates the study design. That’s like comparing apples to zucchini.

There’s so much that doesn’t make sense about the study. It’s so poorly designed and there’s so much lacking that we’d have a field day picking it apart.

Have you found any additional bad essential oil myths about essential oils scientific evidence?



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