Complementary & Alternative Medicine
Index of Herbal Medicines, Supplements and Therapies
The decision to use products containing or claiming to contain eucalyptus oil should be carefully considered.
Eucalyptus Oil (Eucalyptus globulus)
Be aware that the U.S. Food and Drug Administration does not strictly regulate herbs and dietary supplements. There is no guarantee of strength, purity or safety of products containing or claiming to contain eucalyptus. Decisions to use herbs or supplements should be carefully considered. Individuals using prescription drugs should discuss taking herbs or supplements with their pharmacists or health care providers before starting.
Scientists have studied eucalyptus oil for the following health problems:
Eucalyptus oil and eucalyptol (1,8-cineole, a main chemical in eucalyptus oil) are often added to nonprescription decongestant products. However, there is limited scientific study of eucalyptus oil or eucalyptol taken by mouth or inhaled as a decongestant during colds or upper respiratory tract infections. Better research is necessary to make a clear recommendation.
Dental plaque, gingivitis
There is promising research supporting the use of mouthwashes that contain eucalyptus extract or eucalyptol in addition to other ingredients (for example, Listerine). However, it is not known if eucalyptus oil by itself is effective or safe for this use.
Several animal studies report that eucalyptus applied to the skin can reduce pain. However, there is no reliable research in humans to support the effectiveness of eucalyptus oil applied to the skin for headache pain relief.
Preliminary research shows that Citriodiol spray, containing eucalyptus, may reduce the number of tick bites and thereby tick-borne infections, although additional studies are warranted.
Eucalyptus oil has been suggested for many other uses, based on tradition or on scientific theories. However, these uses have not been thoroughly studied in humans, and there is limited scientific evidence about safety or effectiveness. Some of these suggested uses are for conditions that are potentially very serious and even life-threatening. You should consult a health care provider before using eucalyptus oil for any unproven use.
Emphysema and bronchitis
Flu (influenza virus)
Inflammatory bowel disease
Sprains and strains
Urinary tract infection
There are several reports of allergic skin reactions occurring in people using eucalyptus oil products on their skin. Laboratory tests have shown that people with asthma or other allergies may be more likely to have a reaction to eucalyptus. An herbal survey found that 12 percent of asthmatic patients use eucalyptus. Ironically, eucalyptus may cause allergic reactions and may exacerbate asthma. It has been reported that rhinoconjunctivitis and vocal cord dysfunction worsen within minutes of an exposure to eucalyptus.
Eucalyptus should not be taken by mouth unless under the careful supervision of a licensed health care professional. There have been numerous cases of toxicity with oral use, including vomiting, stomach pains, seizures, abnormal heart rhythms, bleeding, coma and death.
In animals, eucalyptus oil has been shown to lower blood sugar levels. It is not clear if these effects occur in humans.
When used on the skin, rashes and burning have been reported.
When used in baths or as aromatherapy, prolonged use has caused difficulty breathing, drowsiness and dizziness. Skin irritation has also been reported.
A strain of bacteria found on eucalyptus may cause infection. Worsening of asthma and rhinoconjunctivitis has been reported.
Cardiovascular collapse and multi-organ failure have been reported following a massive ingestion of mouthwash containing phenolic compounds (eucalyptol, menthol, thymol).
Pregnancy And Breast-Feeding
All forms of eucalyptus oil should be avoided by pregnant or breast-feeding women because of its known toxicity. It is not clear if eucalyptus oil is passed to babies through breast milk, but there have been cases of infant deaths from taking eucalyptus oil by mouth.
Interactions with drugs, supplements and other herbs have not been thoroughly studied. The interactions listed below have been reported in scientific publications. If you are taking prescription drugs, speak with your health care provider or pharmacist before using herbs or dietary supplements.
Interactions With Drugs
Eucalyptus oil taken by mouth, applied to the skin or used as aromatherapy may increase the amount of drowsiness caused by some drugs. Examples include benzodiazepines, such as lorazepam (Ativan); barbiturates, such as phenobarbital; narcotics, such as codeine; and alcohol. Caution is advised while driving or operating machinery. There is evidence that eucalyptus may interfere with the way the liver breaks down certain drugs. As a result, eucalyptus may cause the levels of these drugs in the body to be too high, leading to serious side effects.
In animals, eucalyptus oil has been shown to lower blood sugar levels. Caution is advised if you are also taking drugs that may lower blood sugar levels. Patients taking oral drugs for diabetes or using insulin should be monitored closely by their health care provider while taking eucalyptus oil. Dosing adjustments may be necessary. Use of aromatherapy for long periods of time may also cause this reaction. The drug 5-fluorouracil may be more absorbed through the skin when applied with eucalyptus oil. If you are taking 5-fluorouracil for a skin condition, speak with your health care provider or pharmacist before you also use eucalyptus oil.
Interactions With Herbs And Dietary Supplements
Eucalyptus oil taken by mouth, applied to the skin or used as aromatherapy may increase the amount of drowsiness caused by some herbs or supplements, such as valerian.
Caution is advised while driving or operating heavy machinery. Eucalyptus oil may lower blood sugar levels. Oral use or use as aromatherapy for long periods of time should be avoided in people taking other agents that lower blood sugar levels, such as bitter melon
). In theory, eucalyptus oil may increase the blood levels of herbs broken down by the liver, such as chasteberry (Vitex agnus-castus
). Eucalyptus oil may increase the effects of plants that contain chemicals called pyrrolizidine alkaloids, such as comfrey (Symphytum officinale
The doses listed below are based on scientific research, publications or traditional use. Because most herbs and supplements have not been thoroughly studied or monitored, safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients even within the same brand. Combination products often contain small amounts of each ingredient and may not be effective. Appropriate dosing should be discussed with your health care provider before starting therapy; always read the recommendations on a product's label. The dosing for unproven uses should be approached cautiously, because scientific information is limited in these areas.
Eucalyptus should not be taken by mouth, except under the supervision of a licensed health care professional. Fatal reactions have been reported.
Adults (Aged 18 Or Older)
Aromatherapy or inhalation: A dose of two to four drops of eucalyptus oil in a vaporizer or a tincture containing 5 percent to 10 percent eucalyptus oil has been used.
On the skin: An oil-based formula containing 5 percent to 20 percent eucalyptus or an alcohol-based formula containing 5 percent to 10 percent has been used. Concentrations higher than this may cause skin irritation. Always read product labels. In one study, topical lemon eucalyptus extract spray (Citriodiol) was applied daily for two weeks to the lower extremities to reduce tick attachment.
Children (Younger Than 18)
Eucalyptus oil should not be given to young children or infants in any form (including aromatherapy) because of reports of severe reactions. For older children, use should only be under the supervision of a licensed health care professional.
Eucalyptus oil has been suggested for many conditions, but no use is well supported by scientific research. Eucalyptus oil should not be taken by mouth unless under the supervision of a licensed health care professional, because of reports of severe reactions or death. People with allergies or asthma may be at higher risk of adverse effects associated with eucalyptus. Aromatherapy, baths or inhalation may be safe for short periods of time, but lengthy therapy should be avoided because of the risk of serious reactions. On the skin, you should only use eucalyptus oil products with a low concentration because of the risk of skin irritation. All eucalyptus oil products should be avoided by pregnant or breast-feeding women, infants and children. Consult your health care provider immediately if you experience side effects.
The information in this monograph was prepared by the professional staff at Natural Standard, based on thorough systematic review of scientific evidence. The material was reviewed by the Faculty of the Harvard Medical School with final editing approved by Natural Standard.
- Natural Standard: An organization that produces scientifically based reviews of complementary and alternative medicine (CAM) topics
- National Center for Complementary and Alternative Medicine (NCCAM): A division of the U.S. Department of Health & Human Services dedicated to research
Selected Scientific Studies: Eucalyptus Oil
Natural Standard reviewed more than 275 articles to prepare the professional monograph from which this version was created.
Some of the more recent English-language studies are listed below:
- Darben T, Cominos B, Lee CT. Topical eucalyptus oil poisoning. Australas J Dermatol 1998;39(4):265-267.
- Galdi E, Perfetti L, Calcagno G, et al. Exacerbation of asthma related to eucalyptus pollens and to herb infusion containing eucalyptus. Monaldi Arch Chest Dis 2003;59(3):220-221.
- Gardulf A, Wohlfart I, Gustafson R. A prospective cross-over field trial shows protection of lemon eucalyptus extract against tick bites. J Med Etnomol 2004;41(6):1064-1067.
- Hindle RC. Eucalyptus oil ingestion. N Z Med J 1994;107(977):185-186.
- Huggins UT, Kaplan A, Martin-Harris B, et al. Eucalyptus as a specific irritant causing vocal cord dysfunction. Ann Allergy Asthma Immunol 2004;93(3):299-303.
- Juergens UR, Dethlefsen U, Steinkamp G, et al. Anti-inflammatory activity of 1.8-cineol (eucalyptol) in bronchial asthma: a double-blind placebo-controlled trial. Respir Med 2003;97(3):250-256.
- Schaller M, Korting HC. Allergic airborne contact dermatitis from essential oils used in aromatherapy. Clin Exp Dermatol 1995;20(2):143-145.
- Soo Hoo GW, Hinds RL, Dinovo E, Renner SW. Fatal large-volume mouthwash ingestion in an adult: a review and the possible role of phenolic compound toxicity. J Intensive Care Med 2003;18(3):150-155.
- Tibballs J. Clinical effects and management of eucalyptus oil ingestion in infants and young children. Med J Aust 1995;163(4):177-180.
- Tovey ER, McDonald LG. A simple washing procedure with eucalyptus oil for controlling house dust mites and their allergens in clothing and bedding. J Allergy Clin Immunol 1997;100(4):464-466.
- Webb NJ, Pitt WR. Eucalyptus oil poisoning in childhood: 41 cases in south-east Queensland. J Paediatr Child Health 1993;29(5):368-371.
Last updated May 26, 2005
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