Tea tree has a long history of traditional use. Australian aboriginals used tea tree leaves for healing skin cuts, burns, and infections by crushing the leaves and applying them to the affected area.

Tea tree oil contains consituents called terpenoids, which have been found to have antiseptic and antifungal activity. The compound terpinen-4-ol is the most abundant and is thought to be responsible for most of tea tree oil's antimicrobial activity.

Tea tree oil is obtained by steam distillation of the leaves of Melaleuca alternifolia . Tea tree oil is purported to have antiseptic properties and has been used traditionally to prevent and treat infections. While numerous laboratory studies have demonstrated antimicrobial properties of tea tree oil (likely due to the compound terpinen-4-ol), only a small number of high-quality trials have been published. Human studies have focused on the use of topical tea tree oil for fungal infections (including fungal infections of the nails and athlete's foot), acne, and vaginal infections. However, there is a lack of definitive available evidence for the use of tea tree oil in any of these conditions, and further study is warranted.

Tea tree oil should not be used orally; there are reports of toxicity after consuming tea tree oil by mouth. When applied to the skin, tea tree oil is reported to be mildly irritating and has been associated with the development of allergic contact dermatitis, which may limit its potential as a topical agent for some patients.