By Dr. Kathleen Regan, ND

Did you know that essential oils started with the medieval physician Avicenna (980 – 1037) from Persia who invented the process of distillation? Before that, plants containing essential oils were used in many ancient cultures for the medicinal and fragrant properties found in the whole plant. These oils were some of humanity’s first medicines! Today we have refined the extraction of essential oils with lavender, rosemary, eucalyptus, chamomile, marjoram, jasmine, peppermint, lemon, ylang ylang, and geranium being some of the most popular.

Recently, a number of essential oil companies have begun to recommend pure essential oils for oral consumption. In the multi-level marketing strategy taken by some of these companies, consumers are approached by sales people promoting the health benefits of oral essential oils as safe and effective. I am frequently asked by patients whether this is actually safe. There is no straight forward way to answer this question because there are different ways essential oils can be consumed and there is not a lot of specific research on the safety of oral dosing (especially with the pure oil).

Historically, essential oils have been applied topically to the skin and have been inhaled through the lungs. Oral consumption of isolated essential oils has often been avoided due to fear of toxicity. Essential oils are highly complex mixtures of volatile compounds, and many contain about 20 to 60 individual compounds or more. Once essential oil molecules are in the body, they have multiple actions that can be hard to predict including:

  • Physiological (ex., fennel which contains an estrogen-like compound which influences menstruation and lactation)
  • Biochemical (influencing hormones and enzymes chemically)
  • Psychological (essential oils can rapidly cross the blood brain barrier due to their lipophilic nature and small size where they can affect neurochemicals and transmitters).

Biological activity of essential oils may be due to one of the compounds or due to the entire mixture. We still don’t understand the functions of all the different components of essential oils. Furthermore, once they are taken out of the whole plant and refined to just the oil – they become very potent. This potency has the potential to cause toxicity particularly to the brain, heart, lungs, kidneys, liver, bowels and skin. There are numerous cases reported of overdose from essential oils causing serious harm and even death. Symptoms of an overdose include rapid heart rate, altered breathing pattern, cold and clammy temperature, disorientation and fainting as well as digestive upset and skin rash.

All of this being said, there are a number of research studies that have indicated the benefits of essential oils particularly in the areas of mental health, hormonal balance, bacterial/viral/parasitic infections, irritable bowel syndrome, nausea and cancer (to name a few!) It does seem that smaller doses of essential oils can be very beneficial in these conditions. Lets take a look at a few examples…

Oregano Oil – Antibacterial helping to fight the common cold and flu

Fennel Oil – Can reduce cramping both from menstruation and during labor &delivery. A historical and modern stimulant of breastfeeding. Not to mention antimicrobial, antiviral, anti-inflammatory, anticancer, anti-nausea, anti-fever hepatoprotective and memory enhancing properties.

Lemon Grass, Cinnamon, Clove – Just 3 of over 30 essential oils that have been found to help with H.Pylori, Gastritis and Peptic Ulcer.

Coriander seed, Lemon Balm, Peppermint – Just 3 of a number of essential oils that can help reduce symptoms of Irritable Bowel Syndrome particularly when there is bacterial overgrowth.

Lavender – Effective in the treatment of anxiety.

The FDA provides a list of essential oils that are generally considered safe for consumption.  It can be assumed that these oils are safe for consumption in small doses. What does this mean in terms of dose and how should they be taken?

My opinion on this as a Naturopathic Doctor is that there are a number of essential oils that are beneficial to improve wellness and promote healing of disease. However, because of the concentrated nature of the pure oil and their tendency to irritate skin and mucosal surfaces (mouth, throat, stomach, intestines), they should never be consumed as a pure oil. This is dangerous and can lead to improper dosing, significant gastric upset, disruption of intestinal bacteria and if too much is taken, a trip to the hospital. Long term use of pure essential oils (as seen frequently with oregano oil) upsets our gut bacteria leaving us susceptible to nutritional deficiency, digestive issues and immune system issues. So, I do not recommend taking the pure oil on its own. This leaves 2 other options. Essential oils can be consumed in enteric coated capsules (which means they bypass the stomach and are released slowly in the small intestines) or suspended in a substance which includes a fat such as a milk (ex., cow, nut, coconut milks) or in oils such as olive oil. Contrary to oral dosing instructions found on many websites, water or juice is NOT optimal because oil and water do not mix; this is similar to taking the pure oil on its own. Dosing should not exceed 3-4 drops per cup of milk or tablespoon of oil. This dosage may be repeated up to 3 times per day depending on the essential oil. Dosing an essential oil orally should be limited to 3 weeks and beyond that the supervision of a trained health care practitioner is recommended.




Abdelouaheb Djilani and Amadou Dicko (2012). The Therapeutic Benefits of Essential Oils, Nutrition, WellBeing and Health, Dr. Jaouad Bouayed (Ed.), ISBN: 978-953-51-0125-3, InTech, Available from:

Bergonzelli GE, Donnicola D, Porta N, Corthésy-Theulaz IE. Essential Oils as Components of a Diet-Based Approach to Management of Helicobacter Infection. Antimicrobial Agents and Chemotherapy. 2003;47(10):3240-3246. doi:10.1128/AAC.47.10.3240-3246.2003.

Ostad SN, Soodi M, Shariffzadeh M, Khorshidi N, Marzban H. The effect of fennel essential oil on uterine contraction as a model for dysmenorrhea,pharmacology and toxicology study. J Ethnopharmacol. 2001 Aug;76(3):299-304.

Seifi Z, Beikmoradi A, Oshvandi K, Poorolajal J, Araghchian M, Safiaryan R. The effect of lavender essential oil on anxiety level in patients undergoing coronary artery bypass graft surgery: A double-blinded randomized clinical trial. Iranian Journal of Nursing and Midwifery Research. 2014;19(6):574-580.

Thompson A, Meah D, Ahmed N, et al. Comparison of the antibacterial activity of essential oils and extracts of medicinal and culinary herbs to investigate potential new treatments for irritable bowel syndrome. BMC Complementary and Alternative Medicine. 2013;13:338. doi:10.1186/1472-6882-13-338.

Tisserand R. Essential oils as psychotherapeutic agents. In: Van Toller S, Dodd GH, editors. Perfumery: The Psychology and Biology of Fragrance. New York, NY: Chapman and Hall; 1988. pp. 167–180.