Essential oils conquered medicine cabinets across the West. But do they work?

Loyal customers keep buying products while essential oils skeptics scoff. But the question lingers: What does the science say?

Don’t look now, but deep in your eyelids you likely have tiny mites called demodex. 

Don’t worry, they (probably) won’t hurt you. 

They’re usually benign and sometimes even beneficial, says Keyur Savla, a Ph.D. candidate in vision science at the University of Alabama, as they can perform dead-cell cleanup. But these microscopic creatures also cause serious irritation and infections if they proliferate, which is more common among immune-compromised patients. 

Despite years of training in vision science, Savla hadn’t heard of demodex until his Ph.D. adviser began reviewing demodex treatments for a prestigious British publisher. Savla assisted in the research, spending over a year parsing through existing studies, culminating in a July 2020 article in the Cochrane Database of Systematic Reviews, titled “Tea Tree Oil for Demodex Blepharitis.” 

Yes, tea tree oil

As in, an essential oil — those tiny dark glass bottles of aromatics found in nearly every medicine cabinet along swaths of the I-15 corridor, where essential oils have become a source of good scents, wealth and some healthy skepticism. Critics say the products are overpriced and oversold; boosters swear by them. But many others simply wonder whether there’s evidence that the products work.  

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Two of the industry’s biggest players: Young Living and doTERRA, each of which do well over $1 billion in annual sales, are headquartered in the Beehive State. Given the volume of sales, there’s little question about the product’s popularity — each month thousands of homes are continually infused, suffused and amused by a potpourri of some 90 different essential oils products sold in 10 mL vials. But skeptics say the science to support the broadest claims of these oils has been elusive at best. 

Suddenly, though, essential oils are popping up in legitimate medical research reviews. It’s worth asking: Have essential oils arrived?

Interviews with medical professionals and industry experts, along with hundreds of pages of research and marketing materials, reveal a growing, and in some cases promising, scientific effort to understand what if any benefits are derived from essential oils. Currently, many of the hopes and claims that are marketed still appear to outpace scientific support. Whether these two realities can be reconciled remains to be seen. 


That essential oils have “arrived” at hospitals across America is now a matter of record. No, they’re not curing COVID-19, but major American research hospitals, from Harvard to Stanford, are in fact using aromatic oils as part of a growing push toward “integrative medicine.”  

The aim is to incorporate promising nontraditional methods into more mainstream medical settings, says Ana Baldioli, a physical therapist and the Inpatient Integrative Medicine Coordinator at UCLA Health in Los Angeles.

“Hospitals are stressful,” Baldioli says. “So we try to engage the ‘parasympathetic’ nervous system, which helps the body rest and digest, to counter the ‘sympathetic’ system, which triggers fight or flight.”

At UCLA Health, integrative medicine runs a gamut from therapeutic massage, energy healing (Reiki), traditional Chinese medicine, acupuncture, music, animal therapy, essential oils and more. 

UCLA Health provides three essential oils at every nursing station: lavender, lemon and peppermint, chosen for their popularity and lack of side-effects. The oils are not diffused into the air, Baldioli explains, but rather put on a tissue or cotton ball.

In explaining the role essential oils play, Baldioli cites an example of a reluctant patient who needed a PICC line inserted in her vein. The stress was too much until she was offered a back massage, followed by soothing music, lavender oil and a foot massage during the procedure.

Another case involved an older man with cardiac trouble who was struggling to sleep, his heart racing at 120 bpm. “They played music and gave him lavender oil,” Baldioli says, “and within a few minutes his heart rate had dropped to 80 and he was snoring.” 

Baldioli says UCLA practitioners are careful not to make medical claims regarding the results. And the examples Baldioli cites are anecdotal, not clinical. Anytime she cites possible benefits, Baldioli is quick to use the phrase “patients report.”

Some tools used in integrative medicine programs, like Reiki massage, are at least as controversial as essential oils: research is disputed, and skeptics believe the placebo effect is doing some (if not all) of the heavy lifting. 

But Baldioli thinks placebo would be a feature, not a bug. “We want the placebo effect,” Baldioli tells me. “If we can leverage the power of the mind, give someone something to believe, we’ll use it.”

A woman fills a capsule with essential oils at her home in Santa Clara on Wednesday, Oct. 9, 2019. | Ravell Call, Deseret News

Essential oils are volatile chemicals. They release from a leaf, flower or bark when plants are heated by steam. The oils are “hydrophobic,” so when the steam cools into water, the evaporated oils separate for capture.

The term “essential oils” has been widely used since the 1750s, but the term is still easily misunderstood. It doesn’t mean that the oils are “essential,” as in indispensable, but rather that they are the “essence” (i.e., smell or taste) of the plant or tree from which they’re distilled.

Steam distillation is an old art, probably originally spreading from Persia and the Middle East. In 1556 a German physician named Walter Reiff wrote that lavender oil “is commonly brought to us from the French Provence, filled into small bottles, and sold at a high price.” 

He could have been describing modern day Utah County. 

Those tiny bottles were used medicinally at a time when bad air — “miasma” — was thought to cause various diseases. No surprise, then, that aromatic herbs and oils, which at the very least do smell good, were viewed as cures or preventions. Much later, in the 1880s, germ theory displaced ideas about miasma. 

But the science and industry of plant aromatics was just getting started.

In 1871 the first major essential oils company, Fritzsche Brothers, was founded in New York City, and in the 1920s, a Fritzsche executive by the name of Ernest Guenther began decades of research and world travel, culminating in 1947 in his six-volume “The Essential Oils.”

Guenther’s contribution drives home the chemistry of essential oils. That they are emitted by plants with pleasant odors can mask the fact that these are, first and always, chemicals. If these oils have any salubrious effects beyond placebo, it will be because of these chemicals.

The chemical in tea tree oil that fights demodex, for instance, is “terpinen-4-ol.”

Guenther’s work remains a classic, but a 1949 review in the journal “Nature” hits at a point that still resonates: on the question of what actual function these oils serve, the reviewer notes “too many tentative solutions … for any of them to seem very satisfying.”

In the intervening years, essential oils have found their way into foods, cleaning supplies, fragrances and cosmetics. Fritzsche Brothers prospered, and in 1990, Fritzsche’s successor company was bought by Givaudan, a Swiss corporation, which remains the world’s dominant player in flavors and fragrances with annual sales of around $7 billion.


As the plodding science drags against soaring consumer hopes and revenue demands, some essential oil companies have overplayed their hand.

Sellers have been warned by The Food and Drug Administration and the Federal Trade Commission that they cannot “advertise that a product can prevent, treat, or cure human disease” without offering “reliable scientific evidence, including, when appropriate, well-controlled human clinical studies.”  

Multilevel-marketing firms and their distributors may be held accountable for making misleading or unsubstantiated product claims. Some essential oil companies try to walk the line between marketing and science by deploying bendable phrases that imply potential benefits, but avoid asserting claims. They often use phrases like “said to” or “thought to” or “often used for” in marketing materials. 

But sometimes a company will just let ‘er rip. 

One smaller firm, for example, begins its web description of Angelica Root Oil cautiously enough with “has a reputation for” and “in China is used to,” but then suddenly says the oil has the ability to “clean infections, fight viruses, assist with respiratory ailments, help with indigestion, regulate menstruation, and aid sleep.”

Oh, and it might also “purify the blood.”

More prosaically, and more typical of the industry, another company claims its oils help aid against “the threat of seasonal illnesses.”

According to Nicole Stevens, Director of Clinical Research at doTERRA, the “immune support” claims boil down to something very similar to what Ana Baldioli at UCLA told me: They support the immune system by helping convince the brain to “rest and relax” instead of entering “fight or flight” mode. 

“Lifestyle experiences (such as sleep, diet, stress, drugs, etc.) can put strain on the immune system,” Stevens said via email, adding that essential oils can “help the body function better overall, including the immune system, through mechanisms like stress reduction and improved sleep.”

Essential oils company doTerra’s sprawling campus in Pleasant Grove is pictured on Thursday, July 8, 2021.
Essential oils company doTERRA’s sprawling campus in Pleasant Grove is pictured on Thursday, July 8, 2021. | Spenser Heaps, Deseret News

But others hold out hope that the oils can do much more, and they’re waiting on science to prove it. 

One prominent, level-headed optimist is Robert Tisserand, known for his book “Essential Oil Safety: A Guide for Health Care Professionals,” now in its second edition. An icon in the field, he helps direct an eponymous institute in Southern California.

In our conversation, Tisserand cited ongoing research in Brazil looking at how citrus oil may help fight an aggressive brain cancer. He also said essential oils could soon be helping fight antibiotic resistant bacteria, in synergy with traditional antibiotics. The oils may disarm a key weapon the bacteria use to expel the antibiotic, he says.  

Tisserand can name many other such examples of ongoing research, some of it promising but still early. He discusses a study showing that diffusing certain oils into the room can lower bacterial, fungal and viral counts. But these, too, have not yet reached the stage of any systematic review. And, on the flip side, not much is known about the impact of diffused oils on indoor air pollution.

But Tisserand also points to a handful of essential oil products that are moving into the medicine cabinet. In Germany, lavender oil is used in oral capsules to fight anxiety, with support in clinical trials. Another essential oil has been commercialized to treat acute bronchitis, also supported by randomized controlled studies. 

And then there’s the farm. 

“Essential oils are now widely used in raising pigs and chickens and other animals instead of antibiotics,” Tisserand tells me. Typical mixtures might involve “cinnamon, thyme and oregano.”

And what about tea tree oil, the nemesis of our friends, the demodex? Keyur Savla’s research for Cochrane Review looked at six studies with 562 participants. They concluded that while they still lacked the highest degree of confidence in tea tree oil (the Cochrane standard is quite rigorous), for Savla and others it remains a primary form of treatment. 

Peppermint oil has a slightly different story. The herb has long been thought to be effective in treating the upper and lower digestive tract, and Tisserand referred to a sizable body of research on the topic. 

But not so fast, says Dr. Ellen Stein, a gastroenterologist at Rutgers University. She cites recent controlled research that has shown high placebo effects and only slight benefit from the oil itself. But Stein said she still suggests peppermint to patients. “It’s low cost and low side effects,” she says over the phone. “I advise patients if it works for them, they should use it.” 

Settled science, of course, can be a moving target and Stein knows that the shadow of placebo is there. But like Baldioli at UCLA Health, she can live with that, just like so many consumers who swear by the products.


Robert Tisserand does urge caution about ingesting essential oils. 

“For most essential oils,” Tisserand says, “there is no information about what would be an appropriate dose.” 

The same is true, really, of any delivery method for these products.

For example, some marketing for “Thieves Oil” makes reference to an elaborate backstory about its purported use during the black plague outbreak. Thieves Oil, the Young Living website says, offers “immune system support” and is “cleansing to the digestive system.”  The website also recommends its use on the feet during “cold winter months.”

When I asked about the foot rubbing advice, a Young Living spokesperson replied via email, “Some customers choose to rub oils on their feet because they contain larger pores, which is believed to assist in the absorption of the oil and provides a soothing effect.” 

But other questions remain about how much of a given oil is prudent to put on one’s foot to absorb, and for what measurable effect? Or, how much of another oil should one put in a diffuser, and for how large a space? Or, how much, if any essential oil is safe to ingest?

DoTERRA’s website, for instance, recommends ingesting cinnamon oil, aka casia, “to support healthy cardiovascular, metabolic, and immune function.” Nicole Stevens points to studies that do show metabolic benefits from cinnamon, including a 2020 study led by Giulio Romeo at Harvard that used 500mg daily over 12 weeks, with promising results for pre-diabetic subjects. 

But it’s unclear whether ingesting “one or two drops” of cinnamon oil in lemon oil and water, as suggested on doTERRA’s website, could measurably improve metabolic health — or how the oil compares to swallowing an alternative, like, say, cinnamon powder.

DoTERRA’s research team has published over 20 peer reviewed papers, with more on the way. Some of doTERRA’s current work includes clinical trials testing current products. Other work is basic lab research, including agar plate testing to look at whether an oil can fight specific bacteria, viruses or fungi.

This kind of research may be a long way from clinical trials, but it’s a movement in the direction of more rigorous study by larger distributors like doTERRA and Young Living, something that has been too often missing in an industry marked by sales pitches and lofty claims. 

Some in the industry are hopeful that change will come as research grows, allowing sellers to be more narrow and also more accurate in their claims. Tea tree oil, for example, has also been studied for gum disease, and substantive research suggests that a diluted tea tree oil mouthwash may be as effective as commonly prescribed chlorhexidine, but with fewer side effects.

And then there’s lavender oil. A 2017 research review in the journal Mental Health Clinician has the headline, “Essential oil of lavender in anxiety disorders: Ready for prime time?” Scholars review evidence “from multiple high-quality randomized trials suggests a role … in the treatment of anxiety disorders.” They also note its low cost and low side effects.

In another win for lavender, research at the University of Kentucky suggests that putting the oil on a nearby object reduced hospital intensive care stays for infants who had pre-birth narcotics dependency. An added bonus in this study: The NICU setting eliminates placebo on the patient side.

So while Ana Baldioli and her team at UCLA Health may be open to placebo as a side benefit, there is some evidence that more may be in play. 

“We don’t have all the answers in peer-reviewed publications, but the science is proceeding exactly as it should to fill in the gaps of our understanding,” says Nicole Stevens at doTERRA. “Our mindset has been to do the best we can with current scientific knowledge, and when we know better, do better.”

But reviewing the marketing materials, it’s clear the industry is still riddled with vague and often unsupportable claims. 

“So many pressing questions,” René-Maurice Gattefoss wrote in his groundbreaking “Aromatherapy” book in 1937, “but we will answer them as best we can on the basis of our experience, meager as it is before the immensity of the problem. At least the questions have been raised.” 

That was some 85 years ago. For critics, that’s a long time to wait for answers. But science does move slowly. The question is whether marketing materials can keep the same pace.