Oil from the eucalyptus tree (Eucalyptus globulus) is used today in many over-the-counter cough and cold products, to relieve congestion. Eucalyptus oil is also found in creams and ointments used to relieve muscle and joint pain, and in some mouthwashes.
The eucalyptus tree is native to Australia and serves as the main food for koalas. The oil was used in traditional Aboriginal medicines to heal wounds and fungal infections. Teas made of eucalyptus leaves were also used to reduce fevers. Eucalyptus soon spread to other traditional medicine systems, including Chinese, Indian (Ayurvedic), and Greek and European.
In 19th-century England, eucalyptus oil was used in hospitals to clean urinary catheters. Laboratory studies later showed that eucalyptus oil contains substances that kill bacteria. It also may kill some viruses and fungi. Studies in animals and test tubes also found that eucalyptus oil acts as an expectorant, meaning it loosens phlegm.
There are many species of eucalyptus. Some are the size of an ornamental shrub, and some grow to be giant trees. The type of eucalyptus that is most often used as medicine is called blue gum or Australian fever tree. It can grow as high as 230 feet. Its 4 - 12 inch leaves are dark green and shiny. Its blue-gray bark peels to reveal a cream-colored inner bark.
Although eucalyptus oil has been used orally to treat some conditions, the oil is toxic when taken by mouth and must be diluted. You should not take eucalyptus oil by mouth unless your doctor tells you to.
Cough and cold
Eucalyptus is used in many medicines to treat coughs and the common cold. It can be found in many lozenges, cough syrups, rubs, and vapor baths throughout the United States and Europe. Herbalists often recommend using fresh leaves in teas and gargles to soothe sore throats and treat bronchitis and sinusitis.
Ointments containing eucalyptus are also applied to the nose and chest to relieve congestion. Eucalyptus oil helps loosen phlegm, so many people inhale eucalyptus steam to help treat bronchitis, coughs, and the flu.
Plaque and gum disease
Eucalyptus oil is also rich in cineole, an antiseptic that kills bacteria that can cause bad breath. Eucalyptus is used in some antiseptic mouthwashes, along with other oils, and the mouthwashes have been shown to help prevent plaque and gingivitis.
On the skin, eucalyptus oil has been used to treat arthritis, boils, sores and wounds. The oil is also used in some insect repellents, and one study found that an oil of lemon eucalyptus product may also keep ticks away.
The leaves and oil of the eucalyptus plant are used as medicine. Eucalyptus oil consists of the volatile oil made from the fresh leaves and branch tops of the eucalyptus plant. Eucalyptus leaves contain tannins, which are believed to help reduce inflammation; flavonoids, plant-based antioxidants; and volatile oils.
Eucalyptus oil is available in many products, including liquids and ointments. The leaves of the eucalyptus plant are available fresh, dried (to be used in teas), and in liquid extracts. Commercial cough drops, syrups, vaporizer fluids, liniments, toothpastes, and mouthwashes may contain eucalyptus oil or its active ingredient, cineole. Some of the familiar over-the-counter remedies that contain eucalyptus oil include Listerine, Mentholatum Cherry Chest Rub, and Vicks VapoRub.
Do not give a child eucalyptus orally (by mouth), as it is toxic. Do not give cough drops containing eucalyptus to children under 6.
For a cold, don’t apply eucalyptus oil, salve or chest rub to the face or nose of a child under 2. Ask your doctor before using eucalyptus oil as a chest rub for your child or to inhale steam for congestion.
Do not take eucalyptus oil orally (by mouth) except under your doctor’s supervision, as it is toxic.
Eucalyptus oil (for topical application): add ½ - 1 mL (15 - 30 drops) of oil to 1/2 cup of carrier oil (sesame, almond, olive, etc.). For inhalation, add 5 - 10 drops of oil to 2 cups boiling water. Place towel over head and inhale steam
The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, contain components that can trigger side effects and that can interact with other herbs, supplements, or medications. For these reasons, herbs should be taken with care, under the supervision of a health care provider qualified in the field of botanical medicine.
Eucalyptus oil is generally safe when applied to the skin of adults. Don’t apply eucalyptus oil, salve or chest rub to the face or nose of a child under 2.
People with asthma, seizure disorders, liver or kidney disease, and low blood pressure should not use eucalyptus without first talking to their doctors.
Pregnant and breastfeeding women should not use eucalyptus.
Eucalyptus oil is toxic when taken by mouth. Do not take eucalyptus oil except under your doctor’s supervision.
If you are currently being treated with any of the following medications, you should not use eucalyptus without first talking to your health care provider.
5-Fluorouracil (5-FU) -- In an animal study, using eucalyptus oil on the skin resulted in greater absorption of topical 5-fluorouracil (5-FU), a medication used to treat cancer.
Taking eucalyptus orally may interact with several medications. You should not take eucalyptus by mouth unless under your doctor’s supervision.
Abdullah D, Ping QN, Liu GJ TI. Enhancing effect of essential oils on the penetration of 5-fluorouracil through rat skin. Yao Hsueh Hsueh Pao. 1996;31(3):214-221.
Ashour HM. Antibacterial, antifungal, and anticancer activities of volatile oils and extracts from stems, leaves, and flowers of Eucalyptus sideroxylon and Eucalyptus torquata. Cancer Biol Ther. 2008 Mar;7(3):399-403.
Biruss B, Kahlig H, Valenta C. Evaluation of a eucalyptus oil containing topical drug delivery system for selected steroil hormones. Int J Pharm. 2007;328(2);142-51.
Cermelli C, Fabio A, Fabio G, Quaglio P. Effect of eucalyptus oil on respiratory bacteria and viruses. Curr Microbiol. 2008;56(1):89-92.
Chao SC, Young DG. Effect of a diffused essential oil blend on bacterial bioaerosois. J Essential Oil Res. 1998;10:517-523.
Chen ZZ, Ho CK, Ahn IS, Chiang VL. Eucalyptus. Methods Mol Biol. 2006;344:125-34.
George J, Hegde S, Rajesh KS, Kumar A. The efficacy of a herbal-based toothpaste in the control of plaque and gingivitis: a clinico-biochemical study. Indian J Dent Res. 2009 Oct-Dec;20(4):480-2.
Jaenson TG, Garboui S, Palsson K. Repellency of oils of lemon eucalyptus, geranium, and lavender and the mosquito repellent MyggA natural to Ixodes ricinus (Acari: Ixodidae) in the laboratory and field. J Med Entomol. 2006 Jul;43(4):731-6.
Jori A, Bianchetti A, Prestini PE, et al. Effect of eucalyptol (1,8-cineole) on the metabolism of other drugs in rats and man. Eur J Pharmacol. 1970;9:362-366.
Kumar A, et al. Antibacterial properties of some Eucalyptus oils. Fitoterapia. 1988;59:141-144.
Mahdi NK, Gany ZH, Sharief M. Alternative drugs against Trichomonas vaginalis. East Mediterr Health J. 2006;12(5):679-84.
Osawa K, Yasuda H, Morita H, Takeya K, Itokawa H. Macrocarpals H, I, and J from the Leaves of Eucalyptus globulus. J Nat Prod. 1996;59:823-827.
Sadlon AE, Lamson DW. Immune-modifying and antimicrobial effects of Eucalyptus oil and simple inhalation devices. Altern Med Rev. 2010 Apr;15(1):33-47. Review.
Salari MH, Amine G, Shirazi MH, Hafezi R, Mohammadypour M. Antibacterial effects of eucaluyptus globulus leaf extract on pathogenic bacteria isolated from specimens of patients with respiratory tract disorders. Clin Microbiol Infect. 2006;12(2):194-6.
Sartorelli P, Marquioreto AD, Amaral-Baroli A, et al., Chemical composition and antimicrobial activity of the essential oils from two species of Eucalyptus. Phytother Res. 2006;[Epub ahead of print].
Serafino A, et al. Stimulatory effect of eucalyptus essential oil on innate cell-mediated immune response. BMC Immunol. 2008;9:117.
Swanston-Flatt SK, Day C, Bailye CJ, Flatt PR. Traditional plant treatments for diabetes. Studies in normal and streptozotocin diabetic mice. Diabetologia. 1990;33(8):462-464.
Thorsell W, Mikiver A, Tunón H. Repelling properties of some plant materials on the tick Ixodes ricinus L. Phytomedicine. 2006 Jan;13(1-2):132-4.
Tovey ER, McDonald LG. Clinical aspects of allergic disease: A simple washing procedure with eucalyptus oil for controlling house dust mites and their allergens in clothing and bedding. J Allergy Clin Immunol. 1997;100:464-467.
Webb NJ, Pitt WR. Eucalyptus oil poisoning in childhood: 41 cases in south-east Queensland. J Paediatr Child Health. 1993;29(5):368-371.
Woolf A. Essential oil poisoning. Clin Toxicol. 1999;37(6):721-727.