About Eucalyptus Essential Oil
Eucalyptus essential oil (E. smithii, E. globulus, E. radiata) are distilled from the leaves of the tree. Both E. globulus and E. radiata are rich in 1,8-cineole or eucalyptol. This active ingredient is also the ingredient which poses a risk to very young children. Eucalyptus citriodora (also frequently referred to as lemon eucalyptus) is rich in citronellal and is not an acceptable substitute for other eucalyptus options.
Actions & Indications
Eucalyptus essential oils are frequently used in botanical medicine for coughs and colds. They have a long tradition of use, but the specifics regarding various species are not often discussed. While many aromatherapists prefer E. radiata or E. smithii, most clinical research is on E. globulus. Therefore, the research included on this page is specific to E. globulus unless specified otherwise.
Eucalyptus essential oil is an immune modulator, expectorant, and anthelmintic agent, according to the scientific evidence available. Eucalyptus oils are frequently used for respiratory complaints, though safety considerations make this application controversial. The research on eucalyptus essential oil is summarized as follows.
Sore Throat: Inhalation of eucalyptus and peppermint oils is often used for upper respiratory health, but spraying the oils directly on the throat in a sore throat spray has been found to effectively reduce upper respiratory symptoms including sore throat, hoarseness, and cough. These results are rapid, with symptom reduction apparent only 20 minutes after application.
Laboratory Research Studies
Respiratory Complaints: A 2008 study evaluated E. globulus oil on several bacteria and viruses that are related to common respiratory infections. A total of 120 isolates were used for evaluation. The essential oil was administered in a laboratory setting to determine the MIC (minimum inhibitory concentration) and the variation of effectiveness. While most of the microbes evaluated were susceptible to the eucalyptus oil, the researchers noted differences in their results when compared to results from previous studies. These variations might explain the varying results obtained when natural products such as eucalyptus oil are used in crude form, not as a standardized product. This revisits the debate about standardization. If essential oils are to be used for aromatic medicine, the natural variations in chemical composition will result in inconsistent results from the oils.
A similar study conducted in 2008 evaluated the effects of eucalyptus oil on the immune system in both an in vivo and an in vitro setting. The study found that eucalyptus oil was able to successfully stimulate the immune system, improving immune function, and that it did so without stimulating the production of pro-inflammatory cytokines, which are linked to many immune disorders. Therefore, the oil appears to have the ability to improve immune function, without worsening the symptoms or effects of inflammatory disorders.
The practical application of these studies indicates a need for standardization with an oil that can be both beneficial and harmful, depending on the dose. It also indicates a need for additional research to evaluate the efficacy and potential safety of the internal use of eucalyptus oil for respiratory complaints. Human studies on the oil for respiratory infections and complaints do not yet exist.
Clinical Research Studies
Upper Respiratory Infections: Eucalyptus essential oil has been used to treat URIs in children for over 100 years. It is a core ingredient in Vicks Vapor Rub and helps to promote clear breathing. In a 2010 study, a vapor rub was compared to placebo to establish efficacy and safety for nighttime coughing. Eucalyptus was found to reduce cough severity, congestion, and sleep difficulty for both children and parents.
Asthma: Under trained administration, 1,8 cineole (the active component of eucalyptus EO) was ingested at 200mg, 3x a day to patients who suffer from asthma. The outcomes being measured were quality of life, asthma symptoms, and lung function. After the six month treatment period, the 1,8 cineole patient group had significantly greater scores in all three areas. Note that internal dosing requires advanced training in aromatic medicine, so this should not be attempted at home without consulting with a professional.
COPD: Similarly to the above study, 200mg of 1,8 cineole 3x day was administered to 242 COPD patients over a 6 month period (which included wintertime). The treatment boosted lung function by reducing airway inflammation. Again, internal dosing should not be attempted without advanced training or consulting with a professional.
Eucalyptus Essential Oil Safety
- Eucalyptus essential oil should not be applied to the face or chest of babies or small children.
- Medicinal inhalation is contraindicated for children younger than the age of 2. (Note: this does not apply to routine inhalation from skincare products or household products as most personal care products do not produce a medicinal dose.)
- Ingestion for children under the age of 7 should be avoided.
- Ingestion of eucalyptus essential oil can increase detoxification of other drugs, decreasing the half life and effectiveness. Therefore, those who are taking other drugs should avoid the internal use of eucalyptus oil.
Safety Concerns: Numerous documented reports of eucalyptus poisoning among young children have led to a great debate regarding the appropriate use of this oil. A 1997 study evaluates the reports of poisoning in children by surveying 109 cases of eucalyptus oil poisoning in children younger than 5 that occurred within a single year in Victoria, Australia. This study found that 63% of children presenting to the emergency room with eucalyptus oil were admitted, compared to 47% of all poisoning cases. This indicates that eucalyptus oil poisoning is more severe than other cases of common childhood poisoning. Additional eucalyptus poisoning reports are outlined in the 2012 systematic review of essential oil adverse events. Negative effects include loss of consciousness, slurred speech, ataxia (involuntary muscle movement), and coma. Most adverse events are documented in children under the age of 7.
These safety concerns lead to cautious contraindications for the internal use of the oil. However, eucalyptus is also frequently included in many commercial preparations. For aromatic medicine, the literature appears to suggest the complete avoidance of internal use by susceptible individuals with extreme care in the suitable dosing for otherwise healthy adults. While the LD50 is outlined below, it should be emphasized that this is an average and the actual accounts have a wide variance.
Topical Application: Eucalyptus essential oil is not frequently used in skincare products. Medicinal applications must be diluted. Because dosing is critical, it should be diluted into a semi-solid preparation such as a balm or ointment, not merely combined with a carrier oil. This prevents accidental spread of the application to a greater portion of the body.
In topical applications, results can be achieved with as little as 1-3% total concentrations of eucalyptus essential oils. While greater concentrations can be safely used for specific purposes, it is rarely necessarily to exceed 3% total for an otherwise healthy adult with a total of 1-2 tsp per application, 2-3 times per day. For children 2-6, 1% concentration is sufficient as a chest rub with 1/2 tsp a sufficient dose up to 2-3 times per day.
Ingestion: A single drop on a sugar cube is recommended as the average dose for a cough or cold. This can be repeated every 2 hours, as needed. The equivalent can be obtained through a syrup, honey, or chewable preparation. Prior to ingestion, the above cautions should be evaluated. Total daily dosage: 9-12 drops for adults; 2 drops per day for children 6-12 with a dose of 1/4 drop every 4-6 hours.
LD50: E. globulus 4.4 g/kg (oral); E. citriodora > 5g/kg (oral); E. smithii 2.48 g/kg (oral) However, it should be noted that fatalities have been reported with consumption of as little as 4mls of eucalyptus oil.
Tips & notes
Cooking Tips: Eucalyptus essential oil is not used in culinary preparations.
Methods of Administration: Topical applications include semi-solid preparations such as a balm or ointment. For internal use, syrups, honeys, and chewables are ideal preparations for all varieties of eucalyptus oil as they enable the user to reduce the dosage to 1/2 a drop, which can be administered twice a day.
Cermelli, C., Fabio, A., Fabio, G., & Quaglio, P., (2008). Effect of eucalyptus essential oil on respiratory bacteria and viruses. Current Microbiology. 56:89-92.
Day, L., Ozanne-Smith, J., Parsons, B., Dobbin, M., Tibbals, J., (1997). Eucalyptus oil poisoning among young children: mechanisms of access and the potential for prevention. Australian and New Zealand Journal of Public Health. 21(3):297-302.
Posadzki, P., Alotaibi, A., & Ernst, E., (2012). Adverse effects of aromatherapy: a systematic review of case reports and case series. International Journal of Risk and Safety in Medicine. 24:147-161.
Serafino, A., et al. (2008). Stimulatory effect of the eucalyptus essential oil on innate cell-mediated immune response. Immunology. 17(9).
Worth, H., & Dethlefsen, U. (2012). Patients with asthma benefit from concomitant therapy with cineole: a placebo-controlled, double-blind trial.Journal of Asthma, 49(8), 849-853.
Worth, H., Schacher, C., & Dethlefsen, U. (2009). Concomitant therapy with Cineole (Eucalyptole) reduces exacerbations in COPD: a placebo-controlled double-blind trial. Respiratory research,10(1), 1.