Tea tree oil

[1][2] 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.

There is little evidence for the effectiveness of tea tree oil in treating mite-infected crusting of eyelids,[3] although some claims of efficacy exist.

[2][7][12] A 2015 Cochrane review of acne complementary therapies found a single low-quality trial showing benefit on skin lesions compared to placebo.

[13] Tea tree oil was also used during World War II to treat skin lesions of munitions factory workers.

[2][7][19][12] It may cause drowsiness, confusion, hallucinations, coma, unsteadiness, weakness, vomiting, diarrhoea, nausea, blood-cell abnormalities, and severe rashes.

[24] Tea tree oil potentially poses a risk for causing abnormal breast enlargement in men[25][26] and prepubertal children.

[29] In dogs and cats, death[30][31] or transient signs of toxicity (lasting two to three days), such as lethargy, weakness, incoordination, and muscle tremors, have been reported after external application at high doses.

[37] Whereas the availability and nonproprietary nature of tea tree oil would make it – if proved effective – particularly well-suited to a disease such as scabies that affects poor people disproportionately, those same characteristics diminish corporate interest in its development and validation.