The eucalyptus tree is a large, fast-growing evergreen that is native to Australia and Tasmania. The tree can grow to 375-480 feet (125-160 meters). Eucalyptus belongs to the myrtle (Myrtaceae) family. There are more than 300 species of eucalyptus, and Eucalyptus globulus is the most well-known species. One species (E. amygdalin) is the tallest tree known in the world. The tree grows best in areas with an average temperature of 60°F (15°C).
Eucalyptus trees constitute over 75% of the tree population of Australia. The eucalyptus tree is also known in Australia as the blue gum tree or malee. Other names for eucalyptus include Australian fever tree and stringy bark tree. The name is actually derived from the Greek word "eucalyptos," which means "well covered," and refers to the cuplike membrane that covers the budding flowers of the tree.
The bluish green leaves carry the medicinal properties of the tree and grow to a length of 6-12 inches (15-30 cm). While the leathery leaves are the sole food for koala bears, the leaves also contain a fragrant volatile oil that has antiseptic, expectorant, antibacterial, anti-inflammatory, deodorant, diuretic, and antispasmodic properties. Other constituents of the leaves include tannins, phenolic acids, flavonoids (eucalyptin, hyperin, hyperoside, quercitin, quercitrin, rutin), sesquiterpenes, aldehydes, and ketones.
Eucalyptus oil is obtained through a steam distillation process that removes the oil from the fresh, mature leaves and branch tips of older trees. Approximately 25 species of eucalyptus trees in Australia are grown for their oil.
There are three grades of eucalyptus oil: medicinal, which contains the compound eucalyptol (also called cineol); industrial, in which a component of the oil is used in mining operations; and aromatic, which is used in perfumes and fragrant soap products. These oils vary greatly in character. When choosing an oil for therapeutic use, it is important to know from what species the oil was derived. Species used medicinally include E. globulus, which contains up to 70% eucalyptol; E. polybractea, which contains 85% eucalyptol; and E. Smithii. Eucalpytus amygdalina and E. dives contain little eucalyptol and are used to separate metallic sulfides from ores in the mining industry. Eucalyptus citriodora contains a lemon-scented oil and is an ingredient in perfumes, as is E. odorata and E. Sturtiana. Two species, E. dives and E. radiata, have oils with a strong peppermint odor.
The most common species grown for its medicinal oil is Eucalyptus globulus. The eucalyptol found in this species is a chief ingredient in many over-the-counter cold and cough remedies, such as cough lozenges, chest rubs, and decongestants. It acts to stimulate blood flow and protects against infection and germs. The British Pharmocopoeia requires that commercial eucalyptus oils contain 55% eucalyptol by volume.
The Australian aborigines have used eucalyptus for hundreds of years as a remedy for fever, wounds, coughs, asthma, and joint pain. Australian settlers named the eucalyptus the fever tree because of its disease-fighting properties. Baron Ferdinand von Miller, a German botanist and explorer, was responsible for making the properties of eucalyptus known to the world in the mid-1800s. Likening eucalyptus' scent to that of cajaput oil (a disinfectant), von Miller suggested that eucalyptus might also be used as a disinfectant in fever districts. Seeds of the tree were sent to Algiers, France and planted. The trees thrived and, because of the drying action of the roots, turned one of the marshiest areas of Algiers into a dry and healthy environment, thereby driving away malaria-carrying mosquitoes. Eucalyptus trees were then planted in temperate areas around the world to prevent malaria. As a result, eucalyptus trees are now cultivated in China, India, Portugal, Spain, Egypt, South and North Africa, Algeria, South America, and in the southern portion of the United States.
Commercial production of eucalyptus began in Victoria, Australia in 1860. The nineteenth century eclectic doctors adopted eucalyptus as a treatment for fevers, laryngitis, asthma, chronic bronchitis, whooping cough, gonorrhea, ulcers, gangrenous tissue, edema, and gastrointestinal disturbances. European doctors used eucalyptus oil to sterilize their surgical and medical equipment. Eucalyptus leaves were often made into cigars or cigarettes and smoked to relieve asthma and bronchial congestion.
Modern medicines around the world have included eucalyptus in their practices. Indian ayurvedics use eucalyptus to treat headaches resulting from colds. Eucalyptus is listed in the Indian Pharmacopoeia as an expectorant and in the Chinese Pharmacopoeia as a skin irritant used in nerve pain. In France, eucalyptus leaves are applied topically to relieve congestion from colds and to treat acute bronchial disease. A standardized eucalyptus tea is licensed in Germany to treat bronchitis and throat inflammations. Eucalyptus is also an ingredient in German herbal cough preparations. The German Commission E has approved the internal use of eucalyptus to treat congestion of the respiratory tract, and the external use to treat rheumatic complaints. In the United States, eucalyptus is a component of many decongestant and expectorating cough and cold remedies, such as cough drops, cough syrups, and vapor baths. Eucalyptus is often used in veterinary medicine. It is used to treat horses with flu, dogs with distemper, and to treat parasitic skin conditions.
Eucalyptus is most popular for its ability to clear congestion due to colds, coughs, flu, asthma, and sinusitis. The tannins found in eucalyptus have astringent properties that reduce mucous membrane inflammation of the upper respiratory tract. Eucalyptol, the chemical component of the oil, works to loosen phlegm. Cough drops containing eucalyptus promote saliva production, which increases swallowing and lessens the coughing impulse. Earaches can also be treated with eucalyptus. When inhaled, the eucalyptus fumes open the eustachian tubes, draining fluids and relieving pressure. Eucalyptus enhances breathing, which makes it an effective remedy for asthma, bronchitis, sinusitis, whooping cough, and colds.
Eucalyptus is a component of many topical arthritis creams and analgesic ointments. When applied to the skin, eucalyptus stimulates blood flow and creates a warm feeling to the area, relieving pain in muscles and joints.
The oil extracted from the eucalyptus leaf has powerful antiseptic, deodorizing, and antibacterial properties. It is especially effective in killing several strains of Staphylococcus bacteria. A mixture of 2% eucalyptus oil evaporated in an aroma lamp has been shown to destroy 70% of the Staphylococcus bacteria in the affected room. When the oil is applied to cuts, scrapes, and other minor wounds, it inhibits infections and viruses. A 2002 report out of Australia made researchers around the world take note when two cases of patients with staph infections resistant to traditional antibiotic therapy responded to a mixture of eucalyptus leaf oil abstract. The Australian researchers recommended formal clinical trials to test the therapy, based on an ancient aboriginal remedy. Eucalyptus also fights plaque-forming bacteria and is used to treat gum disease and gingivitis.
In large doses, the oil can be a kidney irritant and can induce excretion of bodily fluids and waste products. Eucalyptus oil added to water may be gargled to relieve sore throat pain or used as a mouthwash to heal mouth sores or gum disorders. Consequently, eucalyptus is an ingredient in many commercial mouthwashes.
Eucalyptus' pain-relieving properties make it a good remedy for muscle tension. One study showed that a mixture of eucalyptus, peppermint, and ethanol oils successfully relieved headache-related muscle tension.
Eucalyptus may lower blood sugar levels. Placing a drop of the oil on the tongue may reduce nausea. The oil has also been used to kill dust mites and fleas.
Eucalyptus oil is one of the most well-known fragrances in aromatherapy. Two species of eucalyptus are used in aromatherapy oils: E. globulus and E. citriodora. The essential oil of eucalyptus is used to relieve cramps, cleanse the blood, heal wounds, disinfect the air, and to treat conditions such as asthma, bronchitis, throat and sinus infections, fevers, kidney infections, rheumatism, bladder infections, and sore muscles.
The essential oil can be diluted and added to a massage oil to ease aching muscles. The oil can be added to hot water and inhaled to reduce nasal congestion. It can also be diffused in the room of a sick patient to disinfect the air.
Some believe that inhaling the diffused oil can enhance concentration and thought processes. Studies have shown that inhalation of the cineole compound of eucalyptus stimulates coordination and motor activities in mice. Eucalyptus oil may also uplift the spirit during times of emotional overload or general sluggishness.
Applying a diluted oil to the skin instead of inhaling it increases the rate of absorption into the blood. Often the speed with which it is absorbed is so fast, the odor can be detected on the breath within minutes.
The oil is also an effective febrifuge, and a cold compress with eucalyptus oil added to it has a cooling effect that is useful in helping to reduce a fever. The essential oil of eucalyptus is also used to treat wounds, herpes simplex virus, skin ulcers, and acne. Combined with water, the oil makes an effective insect repellant. Because of its skin-moistening properties, the oil is often an ingredient in dandruff shampoo.
Eucalyptus oil may be combined with other oils that have similar properties, such as niaouli, pine, Swiss pine, hyssop, and thyme oils. It also mixes well with lemon, verbena, balm, and lavender oils.
Eucalyptus is available as a tincture, cream, ointment, essential oil, or lozenge. Many health food stores carry fresh or dried eucalyptus leaf in bulk. Eucalyptus can be ingested through the use of teas or tincture preparations, inhaled, or applied externally.
Eucalyptus infusion is ingested to treat coughs, colds, bronchitis, congestion, and throat infections. To create an infusion, 1 cup of boiling water is poured over 1-2 teaspoons of crushed eucalyptus leaves. The mixture is covered and steeped for 10 minutes and is then strained. Up to 2 cups can be drunk daily.
Inhaling eucalyptus vapors is beneficial for sinus and bronchial congestion that occurs with bronchitis, whooping cough, colds, asthma, influenza, and other respiratory illnesses. A drop of eucalyptus oil or two to three fresh or dried leaves are added to a pan of boiling water or to a commercial vaporizer. The pan is removed from the heat, a towel is placed over the pan and the patient's head, and the patient inhales the rising steam. Patients should close their eyes when inhaling the steam to protect them from eucalyptus' strong fumes.
For relief of muscle aches or arthritis pain, several drops of the diluted oil are rubbed onto the affected area, or a few drops of diluted oil are added to bath water for a healing bath. Adding eucalyptus leaves wrapped in a cloth to running bath water is also effective.
For gum disease, a few drops of diluted oil are placed on a fingertip and massaged into the gums.
Tinctures should contain 5-10% essential oil of eucalyptus. A person can take 1 ml three times daily.
Ointments should contain 5-20% essential oil of eucalyptus. The person should use as directed for chapped hands, joint and muscle pains, and dandruff.
Children or infants should not be treated with eucalyptus. Of special note, eucalyptus oil should not be applied to the facial areas (especially the nose or eyes) of small children or infants. Pregnant or breast-feeding women should not use eucalyptus.
Undiluted eucalyptus oil should never be ingested. Small amounts of undiluted oil (even in amounts as little as one teaspoon) are toxic and may cause circulatory problems, collapse, suffocation, or death. Eucalyptus oil should always be diluted in a carrier oil such as almond, grape-seed, or other vegetable oil before applying to the skin.
Nausea, vomiting, or diarrhea may occur in rare cases. Applying eucalyptus to the skin may cause a rash in those who are sensitive or allergic to eucalyptus.
Eucalyptus works to detoxify the body. If it is used simultaneously with other drugs, the effects of those drugs may be weakened.
Fischer-Rizzi, Susanne. Medicine of the Earth. Rudra Press 1996.
Prevention. The Complete Book of Natural and Medicinal Cures. Rodale Press, Inc., 1994.
"One Answer to MRSA May be Growing on Trees: Eucalyptus Leaves Show Power over Pathogen." Hospital Infection Control 29, no. 1 (January 2002):11.
Teresa G. Odle