Background

• Tea tree oil is obtained by steam distillation of the leaves of Melaleuca alternifolia. Tea tree oil is purported to have antiseptic properties and has been used traditionally to prevent and treat infections. While numerous laboratory studies have demonstrated antimicrobial properties of tea tree oil (likely due to the compound terpinen-4-ol), only a small number of high-quality trials have been published. Human studies have focused on the use of topical tea tree oil for fungal infections (including fungal infections of the nails and athlete's foot), acne, and vaginal infections. However, there is a lack of definitive available evidence for the use of tea tree oil in any of these conditions, and further study is warranted.
• Tea tree oil should not be used orally; there are reports of toxicity after consuming tea tree oil by mouth. When applied to the skin, tea tree oil is reported to be mildly irritating and has been associated with the development of allergic contact dermatitis, which may limit its potential as a topical agent for some patients.

References

• Arweiler NB, Donos N, Netuschil L, et al. Clinical and antibacterial effect of tea tree oil--a pilot study. Clin Oral Investig 2000;4(2):70-73.
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• Bagg J, Jackson MS, Petrina Sweeney M, et al. Susceptibility to Melaleuca alternifolia (tea tree) oil of yeasts isolated from the mouths of patients with advanced cancer. Oral Oncol. 2006;42(5):487-92.
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• Calcabrini A, Stringaro A, Toccacieli L, et al. Terpinen-4-ol, the main component of Melaleuca alternifolia (tea tree) oil inhibits the in vitro growth of human melanoma cells. J Invest Dermatol 2004;122(2):349-360.
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• Caldefie-Chezet F, Guerry M, Chalchat JC, et al. Anti-inflammatory effects of Melaleuca alternifolia essential oil on human polymorphonuclear neutrophils and monocytes. Free Radic Res 2004;38(8):805-811.
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• Carson CF, Ashton L, Dry L, et al. Melaleuca alternifolia (tea tree) oil gel (6%) for the treatment of recurrent herpes labialis. J Antimicrob Chemother 2001;48(3):450-451.
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• Christoph F, Kaulfers PM, Stahl-Biskup E. A comparative study of the in vitro antimicrobial activity of tea tree oils s.l. with special reference to the activity of beta-triketones. Planta Med. 2000;66(6):556-560.
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• Dryden MS, Dailly S, Crouch M. A randomized, controlled trial of tea tree topical preparations versus a standard topical regimen for the clearance of MRSA colonization. J Hosp Infect 2004;56(4):283-286.
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• Enshaieh S, Jooya A, Siadat AH, et al. The efficacy of 5% topical tea tree oil gel in mild to moderate acne vulgaris: a randomized, double-blind placebo-controlled study. Indian J Dermatol Venereol Leprol 2007;73(1):22-5.
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• Hur MH, Park J, Maddock-Jennings W, et al. Reduction of mouth malodour and volatile sulphur compounds in intensive care patients using an essential oil mouthwash. Phytother Res 2007;21(7):641-3.
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• Koh KJ, Marshman G, Hart PH. Tea tree oil reduces histamine-induced skin inflammation. Br J Dermatol 2002;147(6):1212-1217.
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• Martin KW, Ernst E. Herbal medicines for treatment of fungal infections: a systematic review of controlled clinical trials. Mycoses 2004;47(3-4):87-92.
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• Mozelsio NB, Harris KE, McGrath KG, et al. Immediate systemic hypersensitivity reaction associated with topical application of Australian tea tree oil. Allergy Asthma Proc 2003;24(1):73-75.
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• Satchell AC, Saurajen A, Bell C, et al. Treatment of interdigital tinea pedis with 25% and 50% tea tree oil solution: A randomized, placebo-controlled, blinded study. Australas J Dermatol 2002;43(3):175-178.
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• Soukoulis S, Hirsch R. The effects of a tea tree oil-containing gel on plaque and chronic gingivitis. Aust Dent J 2004;49(2):78-83.
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