What is tea tree oil useful for?

Tea tree oil comes from the leaves of the tea tree (Melaleuca alternifolia). It grows in the swampy southeast Australian coast.

The tea tree was named by eighteenth century sailors, who made tea that smelled like nutmeg from the leaves of the tree. The chemicals in tea tree oil might kill bacteria, fungus, and mites, and reduce allergic skin reactions by decreasing swelling.

People use tea tree oil for acne, toenail fungus, and athlete's foot. It's also used for dandruff, lice, bad breath, and other conditions, but there is no good scientific evidence to support its other uses.

Do not confuse the tea tree with the unrelated common tea plant that is used to make black and green teas.

Uses & Effectiveness ?
Possibly Effective for
Acne. Applying a tea tree oil 5% gel appears to work as well as benzoyl peroxide 5% for treating acne. Tea tree oil might work more slowly than benzoyl peroxide, but seems to be less irritating to the face. When applied twice daily for 45 days, tea tree oil can reduce acne severity.
Toenail fungus (onychomycosis). Applying 100% tea tree oil solution to the skin twice daily for 6 months can cure fungal toenail infections in 1 out of 5 people who try it. It can also improve nail appearance and symptoms in 2 out of 3 people after 3-6 months. It seems to work about as well as clotrimazole 1% solution twice daily. But lower concentrations of tea tree oil do not seem to work.
Athlete's foot (Tinea pedis). Applying a tea tree oil 10% cream works about as well as tolnaftate 1% cream for improving symptoms of athlete's foot. But the tea tree oil cream doesn't seem to cure the infection. Applying a stronger tea tree oil solution (25% or 50%) can help to clear up the infection in about half of people who try it for 4 weeks. But this higher concentration doesn't work as well as standard treatments, such as clotrimazole or terbinafine.
There is interest in using tea tree oil for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.