Tea tree oil, derived from an Australian tree, is used as a topical antiseptic. The oil is also called melaleuca oil and is produced mainly from the leaves of Melaleuca alternifolia, a species native to southeast Queensland and the northeastern coast of New South Wales.
Its antiseptic reputation comes from a mixture of aromatic compounds, including terpinen-4-ol. Australian Aboriginal communities used tea-tree plants in traditional practices, while the modern commercial oil industry developed in the 1920s after chemist Arthur Penfold investigated native Australian oils and reported antimicrobial properties.
Tea tree oil is found in some products for minor skin problems, dandruff, acne, superficial wounds, and fungal infections. However, evidence varies by condition, and it is not the same as a regulated substitute for medical antiseptics. Concentrated oil can irritate skin and may cause allergic reactions, particularly after oxidation from exposure to air and light.
The name can cause confusion because “tea tree” applies to several Australian and New Zealand plants. Tea tree oil should never be swallowed: ingestion can cause serious poisoning, including confusion, weakness, vomiting, and coma.