Tea tree oil

What is tea tree oil?

Tea tree oil is an essential oil steam-distilled from the leaves of Melaleuca alternifolia, a plant native to New South Wales and Queensland in Australia. Aboriginal Australians traditionally used tea tree leaves for wounds, burns and insect bites. Today the oil is promoted for external use for acne, athlete’s foot, toenail fungus, lice and other skin problems (NCCIH). Its main active components include terpinen-4-ol (de Groot and Schmidt, 2016).

What the research says

NCCIH says a small amount of evidence suggests topical tea tree oil might help acne and athlete’s foot, though it may not work as well as standard athlete’s foot treatments. For fungal nail infections, only a few studies have been done, and both the amount and quality of the research are insufficient to draw conclusions (NCCIH).

The most cited nail study is a 1994 double-blind randomized trial in 117 people with culture-proven toenail fungus. Participants applied either 100% tea tree oil or 1% clotrimazole solution twice daily for six months, with nail debridement. Culture cure was 18% with tea tree oil and 11% with clotrimazole, and about 60% in each group had partial or full improvement in appearance; about half reported continued improvement three months later (Buck et al., 1994). Both results were modest, and the authors noted that all treatments have high recurrence rates.

A small open study of a nail oil combining vitamin E with lime, oregano and tea tree essential oils reported high cure rates in 20 people, but there was no control group and tea tree was only one component (Alessandrini et al., 2020). The American Academy of Dermatology says small studies suggest tea tree oil may have some benefit for nail fungus, but larger studies are needed to know how effective it is (AAD).

How it’s used in products

Tea tree oil appears in nail oils, foot creams, acne gels, shampoos and mouthwashes, usually at concentrations from a few percent up to pure oil. Many products do not state the amount.

Safety notes are important. Tea tree oil should never be swallowed: NCCIH warns that taking it by mouth can cause confusion, unsteadiness, inability to walk and coma (NCCIH). On the skin, most people tolerate it, but some develop redness or irritation. Tea tree oil has caused more published allergic contact reactions than any other essential oil, and oxidation from age, heat, light or air makes it more allergenic (de Groot and Schmidt, 2016). Store it tightly closed, discard old oil, and test a small area first. NCCIH notes topical products may be safe during pregnancy and breastfeeding. For nail changes that are painful, spreading, or in people with diabetes, see a clinician.