The essential oils market is booming: According to a report from Allied Market Research, the market is expected to reach $11.19 billion by 2022 (1). The report found that the Spa & Relaxation category is the fastest growing application, but Health & Wellness and Cleaning Products are expected to grow.

This category generates plenty of confusion—what does it mean if an oil is steam distilled? Can undiluted oils be applied topically? Are essential oils ingestible? What’s an absolute? If an oil isn’t “therapeutic grade,” is it adulterated or low-quality? Here are the answers.

1) DistillationEssential oils are the highly concentrated, naturally occurring volatile oils obtained from plants. Distillation process varies: Eden Botanicals writes on their website that “Steam distillation involves bubbling steam through the plant material,” vaporizing the essential oils and separating them from the plant matter. The steam is then condensed back into liquid, where the oil is separated from the water. This process is free of chemicals or alcohol, and is often the best method available for most oils.

However, it isn’t always the best method. A blog post from Mountain Rose Herbs explains: “Oils from citrus peels are cold expressed to preserve all of the aromatic botanical goodness that they possess. This process involves puncturing the skins of either the whole fruit or just the fruit peel and pressing the essential oil out. With this process, a little bit of juice is also extracted, which is then separated from the essential oil” (2).

There also are times when neither of these will do: NOW Solutions adds that there are “absolute” essential oils, which come from plants that will handle neither of these methods—often, flowers, which are too delicate for steam distillation. According to NOW, absolute essential oils “require the use of chemical solvents that are removed later in the production process.” NOW offers Rose and Jasmine absolutes, “due to the rarity and high cost of obtaining” steam-distilled versions.

Related: What’s Trending in Essential Oils

2) QualityNot all oils are quality: Dr. Michelle Schoffro Cook cautions in herWholeFoodsweb exclusive “5 Essential Oils for Stress and Depression” that cheap oils may be adulterated with toxic pesticides used in the growing process of the herbs from which the oils are extracted (3). And while certain quality standards do exist, they aren’t ranked and certified by a third-party certification agency—so beware: NOW notes that “There is no official grading system that grades essential oils as A, B, C, or Therapeutic grade. ‘Therapeutic grade’ is simply a marketing claim with no real independent meaning or value, and no credible third-party standards” (4).

This isn’t to say that there is no way to verify quality. The Essential Oils and Flavor Industry uses specifications published in books by Ernest Guenther and George Burdock (4). NOW and many other companies post test results on their site, which can be compared to published standards.

Suzanne Dean, Owner of Tea Tree Therapy, told WholeFoodsthat it's worth looking into where the company is based: In Australia, where Tea Tree Therapy is headquartered, there are in fact government-regulated standards for essential oils. Dean sent us a statement regarding how Tea Tree Therapy's tea tree oil measures up to Australian standards, noting that Australia specifies minimum and maximum amounts of certain components that the government expects to find in quality essential oils.

3) SafetyEssential oils are highly concentrated materials, such that, although the quality oils are natural and pure, one drop contains more of that oil than people would otherwise get from a plant. As such, users should follow basic rules of safety. Diffusion should take place in a properly ventilated room. For topical use, essential oils should be appropriately diluted—NOW offers a chart on their website—and some may not be suitable for topical use at all, like cassia or cinnamon (4). Essential oils not for topical use should be properly labeled as such, but customers should consult a healthcare practitioner if they have any doubts.

Internal use should be discouraged. Ingesting essential oils directly from the bottle is remarkably unsafe. An article onRemedyGrove.comnotes that, for instance, it takes 16 pounds of fresh peppermint leaf to produce one ounce of essential oil—whereas a teaspoon of dried herbs is generally enough to flavor entire baked dishes (5). Eating enough orange, peppermint, lavender, etc., to ingest a whole drop of essential oil would be difficult, and even then, in food form, it would be surrounded by other plant constituents that would aid in the digestion of the essential oil (5). Experts also caution that there could be risk of liver damage. And, of course, there’s always the possibility that the oil could interact with other medications.

When it comes to pets, customers should be particularly careful: Cats and dogs react differently to different oils, and sometimes it’s hard to tell if a pet is having a bad reaction. Customers should consult a vet before using an oil around or on a pet.

More on Essential OilsFor tips and information on carrier oils and diffusers, read “Body Beautiful.” And check out Dr. Schoffro Cook’sblog post on our sitefor information on top-selling oils.WF


  1. “Essential Oil Market by Product and Application—Global Opportunity Analysis and Industry Forecast, 2015-2022,” Allied Market Research. Published 6/2016. Accessed 11/1/2019.
  2. Christine Rice, “Why Cold Expression for Citrus Essential Oils?” com. Published 2/22/13. Accessed 11/1/19.
  3. Michelle Schoffro Cook, “5 Essential Oils for Stress and Depression,” com. Published 7/15/19. Accessed 11/1/19.
  4. “Essential Oil FAQs,” com. Published 3/3/17. Accessed 11/1/19.
  5. Lee Tea, “Is It Safe to Ingest Essential Oils? What the Sales Reps Aren’t Telling You,” com. Published 10/18/17. Accessed 11/1/19.