Contact Dermatitis

Essential Oils Debunked: Separating Fact From Myth

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Essential oils (EOs) are present in products we use at home, at work, and in our environment. In recent years, there has been an increasing trend to use EOs rather than products containing chemicals perceived as harmful by consumers. In this review, we separate the facts from the myths surrounding EOs and provide scientifically sound answers to common questions.

Practice Points

  • Essential oils (EOs) are present in many consumer products, including foods, cosmetics, pharmaceuticals, and household products; patients can develop contact allergy to EOs.
  • Common EO allergens include tea tree oil, ylang-ylang oil, lavender oil, peppermint oil, jasmine absolute, geranium oil, rose oil, turpentine oil, and sandalwood oil.
  • In general, EOs have good safety profiles, but caution must be taken when storing them.
  • When patch testing for potential EO contact allergy, supplemental testing with both commercially available EOs as well as a patient’s own products is necessary given there is strong variability in the composition of EO products.



What is an essential oil?

An essential oil (EO) is defined by the International Organization for Standardization as a ‘‘product obtained from a natural raw material of plant origin, by steam distillation, by mechanical processes from the epicarp of citrus fruits, or by dry distillation, after separation of the aqueous phase—if any—by physical processes.’’1 Steam distillation is the primary method used for the production of commercial EOs,2 and believe it or not, most EOs contain 100 to 250 individual chemical components.3

The term essential oil often is incorrectly used for a variety of products obtained from plant material by methods other than distillation or cold-pressing, such as extraction. Products that are obtained via the extraction method include absolutes found in fine fragrances; hydrolates such as rose water; concretes such as jasmine or violet leaves; and vegetable oils including olive oil, coconut oil, and sesame oil.2 These products are not true EOs.

Where do EOs come from?

Essential oils are produced in many countries around the world.4 Individual oils may be obtained from species of different plants, from different parts of the same plant, or from various cultivars (plants selectively bred to obtain desirable levels of chemical constituents such as monoterpenes or sesquiterpenes and biochemical properties such as antibacterial or antioxidant activities).3,5 It is estimated that EOs can be obtained from approximately 30,000 plant species, but only 150 EOs are produced commercially.2,6

Why are people using EOs? What is their claim to fame?

Essential oils are employed by the flavor, food (eg, soft drinks, milk, candies, chocolate, meats, sausages, alcoholic beverages, spices, herbs, tea, preservatives, animal foods), fragrance, cosmetic, tobacco, and pharmaceutical industries. They also are used in household products (eg, detergents, fabric softeners, air fresheners, candles, incense) and for medicinal purposes (eg, folk and traditional medicine, phytotherapy, balneotherapy, aromatherapy).2 The oils usually are applied to the skin but also can be administered orally, inhaled, diffused through the air, or used by other means.4 One 2019 survey of Minnesota State Fair attendees (N=282) found the most common reasons for using EOs were a desire for alternative treatments (53.4%), the opinion that EOs are safer than traditional therapies (47.6%), and/or failure of standard medical treatments (10.7%). The survey results also indicated that 46.7% of EO users utilized EOs to treat medical conditions or symptoms.7 Of note, review of the website of an international company that produces EOs confirmed that EOs are marketed not only for adults but also for children to help them concentrate,8 sleep,9 improve the appearance of their skin,10 soothe upset stomachs,11 and decrease sniffles due to colds.12

Why are people selling EOs to family and friends? They must be making major bucks!

In general, the cost of EOs depends on the complexity of cultivated plant species; the mode of harvesting, which is sometimes done by hand; and the yield of oil. Prices range from $4.50 to an incredible $150,000 per kilogram.2 On average, one bottle containing 5 to 15 mL of an EO or oil blend can cost anywhere from $7 to $251.13 In the United States, the consumer EO market is partially composed of multilevel/network marketing companies in which direct consumer sales occur via a hierarchy of individual distributors. Goodier et al7 found that 36.4% of participants who obtained EOs from family and friends purchased them through multilevel/network marketing companies. In 2018, individual distributors of an international EO-producing company made on average anywhere from $4 to as much as $1.54 million annually by selling the company’s EO products and enrolling additional members/individual distributors to purchase or sell the company’s EO products.14

Sometimes EOs are described as natural and pure, but are they really?

Just because a product is labeled as “pure” or “natural” does not ensure that it is a good-quality EO. Organically produced (ie, grown without the use of herbicides or pesticides) plant material can include up to 30% of extraneous herbs and weeds, which can change the composition of the oil.2

Lesser-quality EOs are the result of adulteration, contamination, inadequate oil production, or aging.2 Adulteration (eg, cutting, stretching, bouquetting) occurs when foreign substances are introduced into pure EOs for the benefit of a higher profit; to ensure a sufficient supply of oils; or to meet demands for cheaper oils by “stretching” a more expensive, pure oil by combining with a cheaper, less pure oil. Inadequate oil production leading to lower-quality oils can occur when a biomass is incorrectly distilled, either from too much steam or temperatures that are too high or due to lack of adequate cooling units. Aging occurs when the oils are not stored properly, resulting in a change in the chemical composition due to esterification, reduction, and oxidization of chemicals, which leads to the formation of peroxides and hydroperoxides that can be contact allergens.15


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