Eucalyptus oil is the generic name for distilled oil from the leaf of Eucalyptus, a genus of the plant family Myrtaceae native to Australia and cultivated worldwide. The leaves of selected Eucalyptus species are steam distilled to extract eucalyptus oil. The principal constituent of pharmaceutical grade eucalyptus oils is 1,8-cineole (eucalyptol) which must comprise at least 70% of the contents. All eucalyptus oils are composed of complex mixtures of volatile organic compounds. The main group of constituents of eucalyptus oil are monoterpenes. Eucalyptus oil is also used in personal hygiene products for antimicrobial properties in dental care and soaps. It can also be applied to wounds to prevent infection. Eucalyptus oil has a history of wide application, as pharmaceutical, antiseptic, repellent, flavouring, fragrance and industrial uses. Eucalyptus oil may have antibacterial effects on pathogenic bacteria in the respiratory tract. Inhaled eucalyptus oil vapor may be a decongestant and treatment for bronchitis. Pre-clinical results also show that eucalyptus oil stimulates innate cell-mediated immune response by effects on the phagocytic ability of human monocyte derived macrophages.
The main chemical components of eucalyptus oil, eucalyptol and alpha-terpineol, give the essential oil a soothing, cooling vapor. This makes eucalyptus oil useful for massage.