Tea Tree Overview
Captain Cook named this tree after finding that its aromatic, resinous leaves made a satisfying substitute for proper tea. One hundred and fifty years later, an Australian government chemist named A.R. Penfold studied tea tree leaves and discovered their antiseptic properties. Tea tree oil subsequently became a standard treatment in Australia for the prevention and treatment of wound infections. During World War II, the Australian government classified tea tree oil as an essential commodity and exempted producers from military service.
However, tea tree oil fell out of favor when antibiotics became widely available.
Tea tree preparations contain various percentages of tea tree oil. For treating acne, the typical strength is 5% to 15%; for fungal infections, 70% to 100% is usually used; and for use as a vaginal douche (with medical supervision), 1% to 40% concentrations have been used. It is usually applied 2 to 3 times daily, until symptoms resolve. However, tea tree oil can be irritating to the skin, so start with low concentrations until you know your tolerance.
The best tea tree products contain oil from the alternifoliaspecies of Melaleucaonly, standardized to contain not more than 10% cineole (an irritant) and at least 30% terpinen-4-ol. Oil from a specially bred variant of tea tree may have increased activity against microorganisms, while irritating the skin less. ^
In a double-blind, placebo-controlled trial, 158 people with athlete’s foot were treated with placebo, 25% tea tree oil solution, or 50% tea tree oil solution, applied twice daily for 4 weeks. ^ The results showed that the two tea tree oil solutions were more effective than placebo at eradicating infection. In the 50% tea tree oil group, 64% were cured; in the 25% tea tree oil group, 55% were cured; in the placebo group, 31% were cured. These differences were statistically significant. A few people developed dermatitis in response to the tea tree oil and had to drop out of the study, but most people did not experience any significant side effects.
Another double-blind, placebo-controlled trial followed 104 people with athlete’s foot who were given either a 10% tea tree oil cream, the standard drug tolnaftate, or placebo. ^ The results showed that tea tree oil reduced the symptoms of athlete's foot more effectively than placebo but less effectively than tolnaftate. Neither treatment cured the infection in 100% of the cases, but each treatment cured many cases.
A third double-blind study followed 112 people with fungal infections of the toenails, comparing 100% tea tree oil to a standard topical antifungal treatment, clotrimazole. ^ The results showed equivalent benefits; however, because topical clotrimazole is not regarded as a particularly effective treatment for this condition, the results mean little.
In a 4-week, placebo-controlled study of 126 people with mild to moderate dandruff , use of 5% tea tree oil shampoo significantly reduced dandruff symptoms. ^ Unfortunately, this study was not double-blind: the researchers knew which participants were receiving tea tree oil and which were receiving placebo. For this reason, its results can’t be taken as completely reliable. (For more information on why double-blinding matters, see Why Does This Database Rely on Double-blind Studies? )
The best evidence for benefits with tea tree oil as a treatment for acne comes from a randomized double-blind clinical trial of 60 people with mild to moderate acne symptoms. ^ In this study, participants were divided into two groups and treated with placebo or 5% tea tree oil gel. Over the 45-day study period, researchers evaluated acne severity in two ways: by means of counting the total number of acne lesions (TLC) and also by rating acne severity on a standardized index (ASI). The results showed that tea tree oil gel was significantly more effective than placebo at reducing both the number of acne lesions and their severity.