Eucalyptus (Eucalyptus globulus) is a tall evergreen tree native to Australia and Tasmania. Today, most commercial herbal preparations originate in Mediterranean and subtropical regions, including Spain and Morocco. The leaves and oil of the eucalyptus plant are used for medicinal purposes. Eucalyptus oil consists of the volatile oil distilled from the fresh leaves and branch tops of the eucalyptus plant.

Topical ointments containing eucalyptus oil have been used in traditional Aboriginal medicines to heal wounds and fungal infections. Teas containing eucalyptus leaves were also used to reduce fevers. The therapeutic uses of eucalyptus soon spread to other traditional medicine systems, including Chinese, Indian Ayurvedic, and Greco-European.

Throughout the 19th century in England, eucalyptus oil was used in hospitals to clean urinary catheters. Laboratory studies later revealed that eucalyptus oil contains substances with strong antibacterial properties. Studies in animals and test tubes also found that eucalyptus oil acts as an expectorant (loosens phlegm in the respiratory passages), antiseptic (prevents infection), and deodorant. Like eucalyptus oil, the leaves of the eucalyptus plant contain substances that have expectorant, antibacterial, and antiseptic properties, but the leaves are also believed to help reduce inflammation and reduce fevers. In fact, one study conducted in Russia found that an alcoholic tincture containing eucalyptus leaves helps relieve chronic ear infections. Many researchers believe that the beneficial effect of the eucalyptus tincture may have been due to its anti-inflammatory properties.

In addition, eucalyptus has been used traditionally for diabetes. A few animal studies suggests that this folkloric use may prove to have scientific merit. Mice with experimentally-induced diabetes respond to aqueous extracts of eucalyptus by increasing insulin production and reducing blood sugar. These results suggest that it would be worthwhile to study eucalyptus as an adjunctive treatment for diabetes further. Much more research is needed before it is clear how this may apply to people with diabetes.

Today, eucalyptus is commonly used in remedies to treat coughs and the common cold. It can be found in many lozenges, cough syrups, and vapor baths throughout the United States and Europe. Herbalists recommend the use of fresh leaves in teas and gargles to soothe sore throats and treat bronchitis and sinusitis. Ointments containing eucalyptus leaves are also applied to the nose and chest to relieve congestion. Eucalyptus oil helps loosen phlegm, so many herbal practitioners recommend inhaling eucalyptus vapors to help treat bronchitis, coughs, and the flu.

Because eucalyptus has such a sharp, pungent aroma, some aromatherapists recommend using it like smelling salts to revive someone who has fainted. Generally, most aromatherapists suggest placing a drop or two of eucalyptus oil on a cloth and holding it under the nose of the individual who has fainted. Eucalyptus oil is also rich in cineole (a potent antiseptic that kills bacteria responsible for bad breath), so some professional herbalists may also recommend eucalyptus tinctures to treat bad breath.

Eucalyptus is native to Australia, where it is the primary food in the diet of koala bears. Today, eucalyptus is grown in Mediterranean and subtropical regions around the world. 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 medicinally is called blue gum or Australian fever tree. It can grow as high as 230 feet. Its 4- to 12-inch leaves are dark green and shiny. Its blue-gray bark peels to reveal a cream-colored inner bark.

Eucalyptus leaves contain tannins (which are believed to help reduce inflammation), flavonoids (such as quercetin which has antioxidants properties), and volatile oils.

Eucalyptus oil is a rich source of the potent antiseptic substance cineole (sometimes referred to as eucalyptol).

Eucalyptus oil is available in liquids or ointments and the leaves of the eucalyptus plant are available fresh, dried (to be used in tea), and in tinctures (solution made from herb and alcohol, or herb, alcohol, and water). Commercial cough drops, syrups, vaporizer fluid, liniments, toothpaste, and mouthwash may contain eucalyptus oil or its active ingredient, cineole.

Pediatric

Children should not ingest eucalyptus leaves or oil. Cough drops containing eucalyptus should only be given to children older than 6 years of age.

Use of eucalyptus as steam, salve, or chest rub may be appropriate for children. The doses for these uses are similar to those identified below for adults. Eucalyptus oil should not be applied to the face or nose of children under 2 years of age.

Adult

• Eucalyptus leaf as infusion (tea): 1 to 2 grams per cup three times per day
• Eucalyptus leaf tincture (for congestion): 10 to 30 drops per day
• Eucalyptol: 0.05 to 0.2 mL (1 to 2 drops per cup boiling water) daily
• Eucalyptus oil (for topical application): add ½ to 1 mL (15 to 30 drops) of oil to 1/2 cup of carrier oil (sesame, olive, etc.). For inhalation, add 5 to 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 active substances 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 practitioner knowledgeable in the field of botanical medicine.

The American Herbal Products Association gives eucalyptus leaf a class 2d safety rating, indicating that there are restrictions to its use. Individuals with inflammation of the kidneys or gastrointestinal tract, bile duct inflammatory disease, liver disease, or high blood pressure should not use eucalyptus leaf extract. Tannins in the leaves may cause stomach upset or kidney and liver damage if leaf preparations are ingested in large amounts.

Never apply eucalyptus oil to the face or nose of a child under 2 years of age.

Pregnant and breastfeeding women should not use eucalyptus.

When used externally, eucalyptus oil is nontoxic. When taken internally, however, eucalyptus oil is toxic and must be diluted.

If you are currently being treated with any of the following medications, you should not use eucalyptus without first talking to your healthcare provider.

5-Fluorouracil
In an animal study, topical eucalyptus oil enhanced the absorption of topical 5-fluorouracil, a medication used to treat cancer.

Others
Eucalyptus may increase the clearance of pentobarbital, a barbiturate used for seizures, and amphetamine, a stimulant used for narcolepsy and, sometimes, attention deficit/hyperactivity disorder. This means that these medications may be eliminated from the body more quickly than they are supposed to be.

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.

Blumenthal M, Goldberg A, Brinckmann J. Herbal Medicine: Expanded Commission E Monographs. Newton, MA: Integrative Medicine Communications; 2000:118-123.

Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, Ore: Eclectic Medical; 1998:69-70.

Chao SC, Young DG. Effect of a diffused essential oil blend on bacterial bioaerosois. J Essential Oil Res. 1998;10:517-523.

Duke JA. The green pharmacy. Emmaus, PA: Rodale Press; 1997:194-195, 77, 94, 182, 391, 404, 434.

Gray AM, Flatt PR. Antihyperglycemic actions of Eucalyptus globulus (eucalyptus) are associated with pancreatic and extra-pancreatic effects in mice. J Nutr. 1998;128(12):2319–2323.

Gruenwald J, Brendler T, Jaenicke C, et al, eds et al, eds. PDR for Herbal Medicines. 2nd ed. Montvale, NJ: Medical Economics Company Inc; 2000:283-287.

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.

McGuffin M, Hobbs C, Upton R, Goldberg A. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, Fla: CRC Press; 1996.

Newall CA, Anderson LA, Phillipson JD. Herbal Medicines: A Guide for Health Care Professionals. London, England: The Pharmaceutical Press; 1996:72–73.

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.

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.

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.

White L, Mavor S. Kids, Herbs, Health. Loveland, Colo: Interweave Press; 1998:30.

Woolf A. Essential oil poisoning. Clin Toxicol. 1999;37(6):721-727.