Tea tree oil is an essential oil with a fresh camphoraceous odor, ranging in color from pale yellow to nearly colorless and transparent. It is extracted from the leaves of the tea tree. Tea tree oil contains various chemical components, and when exposed to air, it undergoes oxidation, leading to changes in its composition.

Tea tree oil can be used to treat eyelid scabbing caused by mite infections. In traditional medicine, tea tree oil can be applied topically at low concentrations to treat skin conditions.

Tea tree oil is neither a patented product nor an approved drug in the United States, although it has been used in skincare products and is approved as an adjunctive therapy for aromatherapy in Australia. It is toxic if ingested and unsafe for children.

Uses‌
Although tea tree oil is considered useful for treating dandruff, acne, lice, herpes, insect bites, scabies, and skin fungal or bacterial infections, and there is some evidence supporting some of these claims, the number of relevant studies is limited. A 2015 Cochrane systematic review conducted a comprehensive analysis of adjunctive therapies for acne and found a low-quality trial indicating that tea tree oil was beneficial for skin lesions compared to a placebo. During World War II, tea tree oil was also used to treat skin injuries among munitions factory workers.

According to the Herbal Medicinal Products Committee (CHMP) of the European Medicines Agency, traditional usage suggests that tea tree oil may be used to treat "small, superficial wounds, insect bites, and small boils" and may alleviate itching from mild tinea pedis. The CHMP notes that tea tree oil products should not be used for individuals under 12 years old.

Tea tree oil is not recommended for treating onychomycosis, as its efficacy has not been proven. It is also not recommended for treating head lice in children, as its effectiveness and safety have not been established, and it may cause skin irritation or allergic reactions. Tea tree oil is one of many natural products promoted for treating Demodex infections, but the efficacy of 5-50% concentration tea tree oil solutions remains uncertain, and its overall efficacy is offset by adverse reactions and toxicity. Tea tree oil possesses antibacterial, antifungal, and antiviral properties.