|Eucalyptus is a diverse genus of trees (rarely shrubs). There are almost 600 species of eucalyptus, mostly native to Australia, with a very small number found in adjacent parts of New Guinea and Indonesia. The trunk, which can grow to over 100m, is covered with
peeling, papery bark. The leaves on the young plant, up to five years old, are opposite, sessile, soft, oblong, pointed and a hoary blue colour. The mature leaves are alternate, petioled, leathery and shaped like a scimitar. The flowers are solitary, axillary and white, with no petals and a woody calyx. The bark is peeling and papery, and the leaves are susceptible to frosts. Planting can cause ecological problems as the tree requires huge quantities of water, preventing the growth of native plants. 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.
The medicinal properties of eucalyptus reside in its oil. The major constituent in eucalyptus leaves is a volatile oil known as eucalyptol (1,8-cineol). It acts as a decongestant, loosens phlegm, and relieves spasms. Inhaling eucalyptus vapors can help treat bronchitis, coughs, and the flu. Eucalyptus oil is a strong antiseptic and lozenges made from it are useful for lung diseases, colds and sore throats. Applied to the skin, the oil improves local circulation. The essential oil is particularly antiseptic and is useful in massage blends for muscular fatigue. Diluted essential oil rubbed into the chest has a warming and slightly anesthetic effect, helping to relieve respiratory infections. The essential oil is also used in the treatment of arthritis, bronchitis, catarrh, cold sores, colds, coughing, fever, flu, poor circulation, and sinusitis. The leaves of the eucalyptus plant contain substances that have expectorant, antibacterial, and antiseptic properties. Ointments containing eucalyptus leaves are applied to the nose and chest to relieve congestion. Alcoholic tincture containing eucalyptus leaves helps relieve chronic ear infections.
Eucalyptus oil is available in liquids or ointments and the leaves of the eucalyptus plant are available fresh, dried, and in tinctures. The recommended dose used in aromatherapy or inhalation is two to four drops of eucalyptus oil in a vaporizer or a tincture containing 5 percent to 10 percent eucalyptus oil. Powders can be dusted on infected skin, wounds, and ulcerations as needed. Eucalyptus oil should not be given to young children or infants in any form because of reports of severe reactions. Essential oils are naturally high in volatile organic compounds (VOCs). The use of essential oils should be avoided during pregnancy without consulting with a licensed professional. Essential oils should generally not be applied directly to the skin due to their rapid absorption rate. Instead, essential oil should be applied with a carrier oil, such as olive, hazelnut, or any other "soft" oil. Eucalyptus oil needs to be used very cautiously since as little as 3.5 ml of the oil taken internally has proven fatal. It is best for individuals to discuss internal use with a qualified healthcare professional. Side effects from the internal use of eucalyptus can include nausea, vomiting, and diarrhea. Symptoms of overdose include a drop in blood pressure, circulation problems, collapse, and asphyxiation.