This information is shown courtesy of the Linus Pauling Institute  at http://lpi.oregonstate.edu/f-w98/teatrees.html

Australian tea tree oil, which is commercially available in the United States, has a wide range of topical applications and is commonly used to treat skin and respiratory infections. Surprisingly, the oil is active against all three categories of infectious organisms: bacteria, viruses and fungi. Tea tree oil is an effective treatment for many skin conditions, such as cold sores, the blisters of shingles and chicken pox, verrucae, warts, acne, large inflamed spots and nappy rash. It is also effective against fungal infections, such as ringworm, athlete's foot and thrush, as well as dandruff--a mild form of seborrheic dermatitis.

Tea tree oil is rich in terpene alcohols, such as terpinen-4-ol, which is thought to be the active germicidal component, and 1,8-cineol (eucalyptol), which gives eucalypts their characteristic strong fragrance and medicinal properties. High-terpinen-4-ol oils are therapeutically more important than high-cineol oils because the latter irritate mucous membranes and the skin. Numerous instances of contact dermatitis associated with the use of tea tree oil have been reported and resulted in the discovery that 1,8-cineol was the allergen. Most commercial tea tree oils contain less than 10% 1,8-cineol and between 30% and 45% terpinen-4-ol. Nevertheless, the oil should be patch tested on the skin before use.

The antimicrobial activity of tea tree oil has been demonstrated against several common bacterial and fungal pathogens (see table on next page), which were cultured in nutrient media to which tea tree oil was added. It is especially interesting that methicillin and mupirocin resistant Staphylococcus aureus were susceptible to tea tree oil. Terpinen-4-ol was active against all the test organisms, while 1,8-cineol was inactive against them.

A number of studies have compared tea tree oil with conventional medications:

• The topical application of 5% tea tree oil versus 5% benzoyl peroxide has been investigated in the treatment of acne vulgaris caused by the microorganism Propionibacterium acnes. Both compounds reduced the number of acne lesions, although the action of tea tree oil was slower, possibly due to the use of a suboptimal concentration. Tea tree oil produced fewer side effects than the benzoyl peroxide.

   

• The use of 10% tea tree oil cream has been compared with 1% tolnaflate and placebo creams in the treatment of tinea pedis, or ringworm. This is the commonest form of superficial dermal infection caused by several related fungi. Patients in the tea tree group and tolnaflate group had significant clinical improvement, but the tea tree oil did not cure the condition. However, as with the acne study, the concentration of the oil may have been suboptimal. Unlike the oil, tolnaflate use resulted in minor skin irritation.

   

• In another study, the topical application of 1% clotrimazole solution or 100% tea tree oil for the treatment of toenail disease (onychomycosis) resulted in nearly identical clinical improvement.

   

• Gynecological conditions, including vaginal infections like trichomonal vaginitis, have been successfully treated with tea tree oil. Anaerobic (bacterial) vaginosis is usually treated with oral nitroimidazoles like metronidazole, but these drugs may cause toxic side effects, and long-term recurrence is very high. Topical treatment with tea tree oil may be more effective because the abnormal bacterial flora is replaced by normal lactobacillus.

Bacterial and fungal microorganisms against which tea tree oil has been shown to be effective in culture