Tea tree oil, also known as melaleuca oil, is an essential oil with a fresh, camphoraceous odour and a colour that ranges from pale yellow to nearly colourless and clear. It is derived from the leaves of the tea tree, Melaleuca alternifolia, native to southeast Queensland and the northeast coast of New South Wales, Australia. The oil comprises many constituent chemicals, and its composition changes if it is exposed to air and oxidises. Commercial use of tea tree oil began in the 1920s, pioneered by the entrepreneur Arthur Penfold.
There is little evidence for the effectiveness of tea tree oil in treating mite-infected crusting of eyelids, In traditional medicine, it may be applied topically in low concentrations for skin diseases.