A clinical trial compared the topical use of 5% tea tree oil to 5% benzoyl peroxide for common acne. Although the tea tree oil was slower and less potent in its action, it had far fewer side effects and was thus considered more effective overall.^[REF] The effectiveness of tea tree oil was confirmed in a six-week double-blind trial. In that study, participants applied a 5% tea tree oil gel to the affected area twice a day for 20 minutes and then washed it off with tap water.⁹

Tea tree oil has been traditionally used to treat athlete’s foot. One trial reported that application of a 10% tea tree oil cream reduced symptoms of athlete’s foot just as effectively as drugs and better than placebo, although it did not eliminate the fungus.¹⁰

Australian Aboriginals used the leaves of tea tree to treat cuts and skin infections, crushing and applying them to the affected area. Modern herbalists recommend tea tree oil (at a strength of 70–100%) applied moderately in small areas at least twice per day to the affected areas of skin.¹¹ For a variety of reasons, some researchers have suggested that tea tree oil should not be used to treat burns.¹²

A small, preliminary trial found that a mouthwash with diluted tea tree oil was effective in decreasing the growth of Candida albicans and in improving symptoms in AIDS patients with oral Candida infections (thrush) that had not responded to drug therapy.¹³ People in the study took 15 ml of the oral solution (dilution of tea tree oil was not given) four times per day and were instructed to swish it in their mouth for 30 to 60 seconds and then spit it out. For use of tea tree oil as a mouthwash, one should not exceed a 5% dilution and should be extremely careful not to swallow the solution.

The potent effects of some commercial mouthwashes may be due to the inclusion of thymol (from thyme) and eukalyptol (from eucalyptus)—volatile oils that have proven activity against bacteria. One report showed bacterial counts plummet in as little as 30 seconds following a mouthrinse with the commercial mouthwash Listerine™, which contains thymol and eukalyptol.¹⁴ Thymol alone has been shown in research to inhibit the growth of bacteria found in the mouth.^15,16 Because of their antibacterial properties, other volatile oils made from tea tree,¹⁷ clove, caraway, peppermint, and sage,¹⁸ as well as the herbs myrrh¹⁹ and bloodroot,²⁰ might be considered in a mouthwash or toothpaste. Due to potential allergic reactions and potential side effects if some of these oils are swallowed, it is best to consult with a qualified healthcare professional before pursuing self-treatment with volatile oils that are not in approved over-the-counter products for halitosis.

Australian Aboriginals used the leaves of tea tree to treat cuts and skin infections, crushing and applying them to the affected area. Modern herbalists recommend tea tree oil (at a strength of 70–100%) applied moderately in small areas at least twice per day to the affected areas of skin.²¹ For a variety of reasons, some researchers have suggested that tea tree oil should not be used to treat burns.²²

Herbs that directly attack microbes include the following: chaparral, eucalyptus, garlic, green tea, lemon balm (antiviral), lomatium, myrrh, olive leaf, onion, oregano, pau d’arco (antifungal), rosemary, sage, sandalwood, St. John’s wort, tea tree oil, thyme, and usnea.

A 5% solution of tea tree oil has been shown to eliminate oral thrush in people with AIDS, according to one preliminary trial.²³ The volunteers in the study swished 15 ml of the solution in their mouths four times per day and then spit it out. This may cause mild burning for a short period of time after use.

Topically applied tea tree oil has been studied and used successfully as a topical treatment for Trichomonas, Candida albicans, and other vaginal infections.²⁴ Tea tree oil must be diluted when used as a vaginal douche, and should only be used for this purpose under the supervision of a healthcare practitioner. Some physicians suggest using tea tree oil by mixing the full-strength oil with vitamin E oil in the proportion of 1/3 tea tree oil to 2/3 vitamin E oil. A tampon is saturated with this mixture or the mixture is put in a capsule to be inserted in the vagina each day for a maximum of six weeks.