The Eucalyptus tree is indigenous to both Australia and Tasmania. It is classified as an evergreen species, and is considered the most popular of all Australian flora. They are among the tallest trees in the world and are of considerable economic relevance in Australia’s states. The eucalyptus tree provides timber, kino resin, industrial oils, and medicinal oils for exportation and for in-country use.
Eucalyptus are also one of the most popular trees in the world. The Koala Bear, an indigenous marsupial to Australia, has given the tree immeasurable recognition. As the country’s mascot, the Koala is found only in the eucalyptus forests of eastern Australia. Its entire livelihood is dependant upon this plant. The eucalyptus provides Koalas their only food source, and affords these vulnerable animals shelter and protection. Australian aborigines essentially referenced the Koala for their own dietary benefit, using the tree as a natural treatment for fever and skin lesions. The benefits of the eucalyptus tree have been well received by persons throughout the world and is now cultivated for use in various nutraceutical applications.
There are some three hundred different species of the eucalyptus tree. The three main sources for medicinal harvesting are the common eucalyptus (Eucalyptus globulus), Eucalyptus polybractea, and Eucalyptus smithii.  Although the bark of these trees is sometimes used in various eucalyptus supplements, the majority of health benefits are attributed to a specific compound found in the oil of the leaves. This volatile compound is known as cineole, or eucalyptol.  Another oil harvested from eucalyptus leaves, E. Citriodora, is often used for different aromatic preparations. In addition, these oils contain numerous beneficial phytochemicals, including quercetin and caffeic acid.
Eucalyptus is available in nearly all delivery forms, including; liquids, extracts, ointments and whole dried herb preparations. The leaves of the plant are also freshly harvested for use in teas and tinctures. Eucalyptus oil, and its active constituent eucalyptol, are often included as the key ingredient in various vaporizer liquids, liniments, and even mouthwashes.
Historically, eucalyptus oil’s most prominent use has been as an antibacterial agent.  In the 19th century, the oil from certain species of eucalyptus was often dubbed “catheter oil;” as it was commonly used to clean urinary catheters and other general medical instrumentation. Modern clinical study has seemed to solidify this finding. Various in vitro studies have shown eucalyptus oil to be effective at fighting infections caused by certain harmful bacteria, chiefly Bacillus subtilis and Streptococcus.  The primary constituent of E. globulus oil (cineole) may also provide potent antiseptic properties.  Cineole has been shown to kill bacterium that cause halitosis, or bad breath. Eucalyptus remains a popular ingredient in many common alcoholic based rinses.
Eucalyptus oils have also been used in clinical applications for the management of diabetes. Study has shown that animals induced with diabetes exhibited both a reduction in blood sugar levels and an increase in insulin productivity when administered with certain eucalyptus preparations.  It is important to note that this positive result has not been validated in human trials. However, these preliminary findings indicate that eucalyptus may one day provide an effective adjunctive treatment for this condition.
Today, the oils of the eucalyptus plant are among the most frequently used compounds in cough and cold remedies. As with mouthwash, certain lozenges, vapor liquids, and cough syrups often include some percentage of eucalyptus oil. The leaves main medicinal ingredient, cineole, functions similarly to a menthol and has demonstrated expectorant and nasal decongestant activities.  Certain eucalyptus oils also contain the chemical compound tannin, which is thought to provide significant anti-inflammatory effects. This may prove extremely beneficial for soothing areas of the ear, nose, mouth, and throat; especially when these areas are acutely effected by respiratory, and accompanying ailments.
Due to the possible anti-inflammatory nature of certain constituents found in eucalyptus leaves, there have been preliminary studies performed to define its practicality in the treatment of arthritis and muscular pain. Double-blind study has demonstrated the potential for a eucalyptus-based ointment to effectively stimulate tissue by enhancing circulation, and providing reductions of inflammation in specific target areas.  Initial results are promising, but more human research is necessary to accurately assess this form of treatment.
Other possible applications of eucalyptus oil include; insect repellants, headache treatments, and washes; to rid parasites, mites, and allergens from various materials. [9-11]
There are no established or recommended dosages for the use of eucalyptus-based products. Exact dosaging guidelines vary greatly by each manufacturer. It is highly recommended that individuals use such products in accordance to the accompanying instructions. Legitimate eucalyptus supplements should contain preparations consisting of concentrations standardized to a 70 - 85% eucalyptol, or cineole content.  These products should always be diluted before topical and internal applications.
The table below provides examples of tolerable dosages in different supplemental forms of eucalyptus:
|Eucalyptus Form||Adults and Teenagers||Children up to age 12|
|Oil:||300 – 600 milligrams per day (internal)||Not Applicable|
|Whole Leaf:||1 – 3 tsp. (4-6 grams), three X per day||Not Applicable|
|Tincture:||3 – 4 grams per day, (10-30 drops)||Not Applicable|
|Tea:||Potency varies: 1 – 2 grams per cup, three – four X daily||Not Applicable|
Toxicities resulting from the ingestion of eucalyptus are rare, but have occurred. Initial symptoms of eucalyptus induced poisoning are epigastric pain, diarrhea, and vomiting. Severe symptoms include central nervous system depression and possible coma.  If certain species of eucalyptus oils are ingested, amounts as little as 3.5 to 4 milliliters (1 tsp.) may prove life threatening.  Adults ingesting eucalyptus oils are recommended to use it sparingly and with extreme caution; preferably under the care of a certified medical practitioner. The oral supplementation of any eucalyptus-based supplements is not recommended for children of any age.
Eucalyptus-containing supplements are contraindicated for persons suffering from asthma, liver disease, low blood pressure, or in individuals diagnosed with diabetes and inflammatory disorders of the gastrointestinal tract. Topical applications should also never be applied to the face of infants and young children. Infants, children, and asthma suffers are at an elevated risk for developing adverse reactions, which may include bronchial spasms and asphyxiation. 
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