Wikipedia
Cajeput oil is a volatile oil obtained by distillation from the leaves of the myrtaceous trees Melaleuca leucadendra, Melaleuca cajuputi, and probably other Melaleuca species. The trees yielding the oil are found throughout Maritime Southeast Asia and over the hotter parts of the Australian continent. The majority of the oil is produced on the Indonesian island of Sulawesi. The name “cajeput” is derived from its Indonesian name, “kayu putih” or "white wood".
The oil is prepared from leaves collected on a hot dry day, macerated in water, and distilled after fermenting for a night. This oil is extremely pungent, and has the odor of a mixture of turpentine and camphor. It consists mainly of cineol (see terpenes), from which cajuputene, having a hyacinth-like odor, can be obtained by distillation with phosphorus pentoxide. The drug is a typical volatile oil, and is used internally in doses of 2 to 3 minims, for the same purposes as, say, clove oil. It is frequently employed externally as a counterirritant. It is an ingredient in some liniments for sore muscles such as Tiger Balm and Indonesian traditional medicine Minyak Telon.
It is also used as an ingredient in inhalants/decongestants and topical pain/inflammation remedies such as Olbas Oil.