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I have covered a lot of details, therefore, my key points to remember for potential interactions of essential oils with drugs and for any intervention are listed below. These are based on my experience with clients and from my review of the literature above.
- Natural does not mean inert. Any supplement, herb, essential oil, nutraceutical, or drug will impact theorgans of elimination and excretion because they all need to be processed by the body. Interactions with them can occur with nutrients, foods, and between modalities.
- Everyone is different, with different detoxification capacities and abilities to metabolize drugs, supplements, and nutrients. This can result in "unusual" effects for some people. Therefore, it is often helpful to check clinically relevant detoxification SNPs in sensitive patients and to not dismiss them as "head cases" when they report strange responses to any intervention.
- For those on medications that must be dosed and kept within narrow ranges of blood values, allow at least 2-3 hours between taking them and using essential oils. Monitor responses more frequently and during the introduction of the essential oil or additional intervention.
If one is on anticoagulants, such as heparin or warfarin, and/or antiplatelet drugs, such as aspirin, only introduce the use of essential oils if "clotting time" is being monitored. This includes prothrombin time (PT) and international normalized ratio (INR). Some essential oils that may present with the highest risk with these medicationsinclude:
· Birch (Sweet) (Betula lenta)
· Garlic (Allium sativum)
· Oregano (Origanum onites as well as the following synonyms Origanum smyrnaeum, Origanum vulgare, Origanum compactum, Origanum hurtum, Thymbra capitata, Thymus capitatus,Coridothymus capitatus, Satureja capitate)
· Tarragon (Artemisia dracunculus)
· Wintergreen (Gaultheria fragrantissima)43,101
- According to Therapeutic Benefits of Essential Oils, Nutrition, Well-Being and Health, most components of essential oils are taken in then metabolized by limited phase I, followed by glucuronidation and sulfation through the kidneys as polar compounds or exhaled through the lungs as CO2.101
This means that if a person has reported drug and supplement effects in alignment with "sensitive" types, SNPs in phase II metabolism should be considered. Those with compromised kidney health and lung capacity should also be monitored closely. The practitioner should evaluate kidney and lung function in these patients, as they would any intervention.
Overall, there is small risk for accumulation due to their short half-life and fast metabolism.82,10
- Most studies that have reported liver toxicity with essential oils involve ingesting more than 5ml of essential oils at a time.19,102-104 Considering the appropriate dosage should be one to two drops, these reports are not really "toxicity" issues, rather they are overdosages. Furthermore, trials in vitro and in vivo have provided evidence that some essential oils can induce glutathione and act as antioxidants, protecting the liver.
- After over eleven years of using essential oils with my clients and seventeen years of personal use, I have found that some of the earliest signs of inappropriate dosage of essential oils can be complaints of headaches and/or frequent urination.
I have noticed that headaches are usually a result of their aroma, causing overstimulation of easily excitable neurons at a low threshold. This usually occurs in "sensitive patients" that note they commonly react to smell and generally have a high body burden of toxicants. Usually, after supporting their biotransformation pathways with nutrients and herbals and/or supporting functional neurology factors (e.g., oxygenation, blood sugar, mitochondrial and neurological stimulation through exercise), these clients can then introduce essential oils into their protocol. This most often occurs with inhalation methods versus ingestion.
If one is using excessively high dosages, it can overwhelm a compromised metabolic pathway in the liver and kidneys. Due to the fact the kidney is responsible for glucuronidation and sulfation of some essential oils constituents, urination may increase as the body tries to metabolize them. Therefore, be extra cautious with proper dosage and use in those with liver and kidney compromise and/ or with multiple sensitivities.
- Children and those on many medications should use three-quarters to half potency when using essential oils topically and internally. Infants should not use topical or oral routes for essential oils, unless caregivers are well-versed in diluting essential oils. (Specific dosage charts exist for pediatrics and are available online.) I have found many adult clients need less medication, and some even discontinue medications with time, if their prescribing physician works with us and is open-minded and integrative.
- Within the literature, aromatherapy is deemed overall safe and beneficial when used properly and safely.105-108
If you'd like additional details on essential oils, medication interactions, and safety on my essential oils, please visit my essential oils database under the category "children and safety" found at http://dr-lobisco.com/essential-oils-database/.
Internal Usage of Essential Oils: Controversy, Scare Tactics, and Bad Science
Now that we have knowledge of the basic overview of application of essentials and have safety information regarding their biotransformation and metabolism, it is time to discuss how to use them orally. First, let's consider the hesitancy that may be present in a practitioner.
As stated above, this is the most debated method of aromatherapists in the United States. However, this is not the case in France and Germany.5-8,109 The National Cancer Institute states:
Although essential oils are given orally or internally by aromatherapists in France and Germany, use is generally limited to inhalation or topical application in the United Kingdom and United States. Nonmedical use of essential oils is common in the flavoring and fragrance industries. Most essential oils have been classified as GRAS (generally recognized as safe), at specified concentration limits, by the U.S. Food and Drug Administration (FDA). (Refer to the International Federation of Aromatherapists website [www.ifaroma.org/] for a list of international aromatherapy programs.)
What many may not realize is that ingesting essential oils has been practiced worldwide for years via their use as flavoring agents. Currently, many are listed under the Substances Generally Recognized As Safe (GRAS) by the FDA (available at: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=182.20.)
Furthermore, Germany has a history of their internal use and has guidelines issued by The Commission E for their indications.9 For example, fennel essential oil has been used orally for a wide array of intestinal issues.9,110-114 According to the Expanded German E Commission by the American Botanical Council, this essential oil has vast applications and specific dosages of administration:
The Commission E approved the internal use of fennel oil preparations for peptic discomforts, such as mild, spastic disorders of the gastrointestinal tract, feeling of fullness, and flatulence; and also for catarrhs of the upper respiratory tract. Fennel honey was recommended for catarrhs of the upper respiratory tract in children. ESCOP approves the use of fennel syrup or fennel honey for catarrh of the upper respiratory tract in children (ESCOP, 1997).
In Germany, fennel seed is licensed as a standard medicinal tea for dyspepsia. It is also used in cough syrups and honeys (antitussives and expectorants), and stomach and bowel remedies, especially in pediatrics, as aqueous infusion, water (Aqua Foeniculi), drage (lozenge), juice, and syrup. It is often used in combination with aniseed (Leung and Foster, 1996; Wichtl and Bisset, 1994). In the United States, it is also used as a component of galactagogue preparations. Indications for use of fennel oil are similar to those for fennel seed. In Germany and the United States, fennel oil is used as an expectorant component of cough remedies, and also as a carminative component of stomach and bowel remedies in dosage forms including honey and syrup. Traditionally, it is combined with laxative or purgative herbs to counteract or modify their harsh griping effects in the bowels (ESCOP, 1997; Leung and Foster, 1996; Nadkarni, 1976; Wichtl and Bisset, 1994). The Commission E limits the use of fennel seed and fennel oil for up to two weeks and then recommends consulting a physician.111
Although the European Union is currently replacing the German E Monographs by EMA Community Monographs, they are still considered an authoritative reference, according to Mark Blumenthal, the founder and director of the American Botanical Council (ABC).115,116
I believe that this oil is a perfect example of scare tactics regarding ingestion of essential oils. Many proclaim that this essential oil is toxic, dismissing Germany's history of use and its presence in the food supply. This is mostly based on toxicology studies of one of its isolated compounds, estragole, from in vivo and in vitro trials. These are unfounded extrapolations as a 2012 review published in Evidence-based Complementary and Alternative Medicine provides evidence for. The authors state the following reasons for this:
- Studies do not assess quality of the whole fennel oil.
- Metabolism and biotransformation differences in humans and rodents.
o It was reported that human liver cells have a high level of an enzyme that provides protection against the harmful reactants resulting from estragole metabolization in rodents that produce negative effects. (Allylic epoxide hydrolase activity is seven to 10 times higher than that seen in rat liver).
o The article states, "In humans estragole usually enters the body as a component of fennel tea, or as a food that has been seasoned with herb that contains many other substances like nevadensin, epigallocatechine, other flavonoids, and anethole [in essential oil], that have a protective role and so counterbalance to the possible effect of pure estragole."19
The authors of this review conclude, "Consideration of these issues (dose, administration form, and differences in metabolism between species) raises doubts about the conclusion that fennel seed can be 'reasonably anticipated to be a human carcinogen.' It is clear that human and animal metabolism cannot be directly compared but we think data should deserve attention."
These three main points of quality, differences in metabolism and biotransformation, and essential oil synergy should be kept in mind by practitioners when determining the safety and application of essential oils. Furthermore, one should always be cautious to not take at face value headlines and hype that are aimed to produce fear of natural substances.
Table 1: Essential Oils Conversion and Measurement Chart
1 oz. = 30 ml
1 oz. = 600 drops essential oils
1 oz. = 2 Tbsp. or 6 tsp.
Using these conversions:
6 drops of EO per oz. of carrier oil = 1% dilution (1% of 600 drops)
3 drops of EO per Tbsp. or 3 tsp. = 1% dilution (1% of 300 drops)
1 drop of EO per tsp. = 1% dilution
1 drop of essential oil = approximately 0.02 to 0.03 grams =
20-30 milligrams = 20000 micrograms (µg)
30 mg = approximately 1 drop*
*Compiled from references 117-121
*Due to FDA regulations, my affiliations, and legalities, I am unable to make specific references or recommendations of brands.
**There is one branded essential oil company with approval for internal ingestion from the FDA. It is the only dietary supplement line of essential oils.
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Part 2, published in our January issue, looks at the clinical application of ingested essential oils for intestinal discomfort.
References (for Parts 1 and 2, .pdf) were not in our print editions.
Sarah LoBisco, ND, is a graduate of the University of Bridgeport's College of Naturopathic Medicine (UBCNM). She is licensed in Vermont as a naturopathic doctor and holds a bachelor of psychology degree from State University of New York at Geneseo. Dr. LoBisco is a speaker on integrative health, has several publications, and has earned her certification in functional medicine. Dr. LoBisco currently incorporates her training as a naturopathic doctor and functional medicine practitioner through writing, researching, private practice, and her independent contracting work for companies regarding supplements, nutraceuticals, essential oils, and medical foods. Dr. LoBisco also enjoys continuing to educate and empower her readers through her blogs and social media. Her recent blog can be found at www.dr-lobisco.com.