Tea Tree (Melaleuca alternifolia) Research

GENERAL

• The use of plant essential oils against antibiotic resistant microbes is discussed. Key essential oils include basil, cilantro, coriander, cinnamon, clove, curry, garlic, helichrysum, lavender, lemongrass, oregano, peppermint, and tea tree. From: Yang, S. K., Low, L. Y., Yap, P. S. X., Yusoff, K., Mai, C. W., Lai, K. S., & Lim, S. H. E. (2018). Plant-Derived Antimicrobials: Insights into Mitigation of Antimicrobial Resistance. Records of Natural Products, 12(4).
• This was a mega-analysis summarizing the therapeutic actions of tea tree oil, including analgesic, antiviral, antibacterial, antifungal, antiprotozoal, anti-inflammatory, antioxidant, and anticancer.  From:  Yadav, E., Kumar, S., Mahant, S., Khatkar, S., & Rao, R. (2016). Tea tree oil: a promising essential oil. Journal of Essential Oil Research, 1-13.
• This article provided a thorough review of medicinal uses of tea tree oil.  Discussed are antimicrobial, antibacterial, antiviral, antifungal, anti-protozoal, and anti-inflammatory actions.  From:  Carson, C. F., Hammer, K. A., & Riley, T. V. (2006). Melaleuca alternifolia (tea tree) oil: a review of antimicrobial and other medicinal properties. Clinical microbiology reviews, 19(1), 50-62.
• This was a review of the topical uses of tea tree oil.  From:  Crawford, G. H., Sciacca, J. R., & James, W. D. (2004). Tea tree oil: cutaneous effects of the extracted oil of Melaleuca alternifolia. Dermatitis: contact, atopic, occupational, drug, 15(2), 59-66.
• Pharmacological actions were assessed of manuka, kanuka, and tea tree oils.  From:  Lis‐Balchin, M., Hart, S. L., & Deans, S. G. (2000). Pharmacological and antimicrobial studies on different tea‐tree oils (Melaleuca alternifolia, Leptospermum scoparium or Manuka and Kunzea ericoides or Kanuka), originating in Australia and New Zealand. Phytotherapy research, 14(8), 623-629.
• Lis-Balchin, M. (2006). Aromatherapy Science: A guide for healthcare professionals. London: Pharmaceutical Press.
• Tisserand, R. & Young, R. (2014).  Essential Oil Safety.  Second Edition.  Churchill, Livingstone, Elsevier.
• Petersen, D. (2015). Aromatherapy Materia Medica.  Essential oil monographs.  American College of Healthcare Sciences

​SAFETY / CONCERNS

• Lavender and tea tree oil in excessive amounts may have a gynocomastic effect in prepuberty boys do to estrogen enhancing constituents. From: Henley, D. V., Lipson, N., Korach, K. S., & Bloch, C. A. (2007). Prepubertal gynecomastia linked to lavender and tea tree oils. New England Journal of Medicine, 356(5), 479-485.
• Tea tree oil can be toxic and even cause death in dogs and cats.  From:  Bates, N. (2018). Tea tree oil exposure in cats and dogs. The Veterinary Nurse, 9(9), 474-478.
• Contact allergies from tea tree oil usually occur from application of the pure, undiluted oil.  From:  de Groot, A. C., & Schmidt, E. (2016). Tea tree oil: contact allergy and chemical composition. Contact dermatitis, 75(3), 129-143.
• 1,8-cineole is a toxic constituent that can cause skin and mucus membrane irritation as well as liver toxicity, and can be higher in variations of tea tree; skin patch test is required (Petersen, 2015).
• Oxidized oil may have triple the allergenic property (Lis-Balchin, 2006).
• May be unsafe for use with pre-puberty boys (WebMD, n.d. & Henley, et al, 2007).
• Ingestion of tea tree oil is toxic and not recommended (WebMD, n.d.).
• In 311 volunteers, tea tree oil was skin patch tested at various concentrations. There was a very low level of irritancy among participants, but 3 people had potentially allergic reactions. Risk of developing allergic dermititis was less than 1 percent. From: Aspres, N., & Freeman, S. (2003). Predictive testing for irritancy and allergenicity of tea tree oil in normal human subjects. Exogenous Dermatology, 2(5), 258-261.

INSECTICIDAL / PESTICIDAL

• Lavender and tea tree reduced head lice.  From:  Barker, S. C., & Altman, P. M. (2010). A randomised, assessor blind, parallel group comparative efficacy trial of three products for the treatment of head lice in children-melaleuca oil and lavender oil, pyrethrins and piperonyl butoxide, and a. BMC dermatology, 10(1), 6.
• Tea tree and lavender were effective against a wide range of mites, lemon was effective against some mites, but not lice. From:  Williamson, E. M., Priestley, C. M., & Burgess, I. F. (2007). An investigation and comparison of the bioactivity of selected essential oils on human lice and house dust mites. Fitoterapia, 78(7), 521-525.
• Of 53 tested plant oils, bay, caraway seed, clove leaf, lemon eucalyptus, lime, pennyroyal, peppermint, rosewood, spearmint, and tea tree oils were highly effective against the greenhouse whitefly. From:  Choi, W. I., Lee, E. H., Choi, B. R., Park, H. M., & Ahn, Y. J. (2003). Toxicity of plant essential oils to Trialeurodes vaporariorum (Homoptera: Aleyrodidae). Journal of Economic Entomology, 96(5), 1479-1484.
• Tea tree oil and terpinen-4-ol were highly effective in reducing the human mite infection: sarcoptes scabiei.  From:  Walton, S. F., McKinnon, M., Pizzutto, S., Dougall, A., Williams, E., & Currie, B. J. (2004). Acaricidal activity of Melaleuca alternifolia (tea tree) oil: in vitro sensitivity of sarcoptes scabiei var hominis to terpinen-4-ol. Archives of dermatology, 140(5), 563-566.
• Tea tree oil was effective against head lice.  From:  Di Campli, E., Di Bartolomeo, S., Pizzi, P. D., Di Giulio, M., Grande, R., Nostro, A., & Cellini, L. (2012). Activity of tea tree oil and nerolidol alone or in combination against Pediculus capitis (head lice) and its eggs. Parasitology research, 111(5), 1985-1992.
• Tea tree oil was acaricidal against the tick:  Ixodes ricinus.  From:  Iori, A., Grazioli, D., Gentile, E., Marano, G., & Salvatore, G. (2005). Acaricidal properties of the essential oil of Melaleuca alternifolia Cheel (tea tree oil) against nymphs of Ixodes ricinus. Veterinary parasitology, 129(1), 173-176.
• A solution with paw paw, thymol, and tea tree oil was 100% effective in eliminating head lice in participants.  From:  McCage, C. M., Ward, S. M., Paling, C. A., Fisher, D. A., Flynn, P. J., & McLaughlin, J. L. (2002). Development of a paw paw herbal shampoo for the removal of head lice. Phytomedicine, 9(8), 743-748.
• Both 1,8-cineole and terpinen-4-ol from tea tree oil were shown to inhibit acetylcholinesterase, which may be the reason for their insecticidal activity.   From:  Mills, C., Cleary, B. V., Walsh, J. J., & Gilmer, J. F. (2004). Inhibition of acetylcholinesterase by tea tree oil. Journal of Pharmacy and Pharmacology, 56(3), 375-379.
• This was a review of research on using tea tree oil against the mite that causes demodicosis of the skin.  From:  Lam, N. S. K., Long, X. X., Griffin, R. C., Chen, M. K., & Doery, J. C. (2018). Can the tea tree oil (Australian native plant: Melaleuca alternifolia Cheel) be an alternative treatment for human demodicosis on skin? Parasitology, 1-11.
• Tea tree oil and terpinen-4-ol were highly effective in reducing the human mite infection: sarcoptes scabiei (scabies).  From:  Walton, S. F., McKinnon, M., Pizzutto, S., Dougall, A., Williams, E., & Currie, B. J. (2004). Acaricidal activity of Melaleuca alternifolia (tea tree) oil: in vitro sensitivity of sarcoptes scabiei var hominis to terpinen-4-ol. Archives of dermatology, 140(5), 563-566.
• Leptospermum petersonii, Prostanthera melissifolia, and Melaleuca alternifolia were the three most effective oils to offer short term repellency against mosquitos. From: Maguranyi, S. K., Webb, C. E., Mansfield, S., & Russell, R. C. (2009). Are commercially available essential oils from Australian native plants repellent to mosquitoes?. Journal of the American Mosquito Control Association, 25(3), 292-301. 
• Australian plants demonstrated varying degrees of insect (mosquito) repellency and included: eucalyptus, tea tree, cajuput, manuka, balm mint bush, fragonia, myrtle, cypress, and niaouli. From: Webb, C. E. (2014). Insect repellents derived from Australian plants and implications for public health messages. Insect repellents handbook, 213.
• The repellency of Austrailian plants of the Myrtaceae family is reviewed. From: Webb, C. E. (2014). Insect repellents derived from Australian plants and implications for public health messages. Insect repellents handbook, 213.

​​ANTI-PARASITE

• Scabies is a contagious, parasitic skin disease.  In this review of research, tea tree showed to have anti-parasitic and anti-inflammatory actions against scabies.  More research is warranted.  From:  Thomas, J., Carson, C. F., Peterson, G. M., Walton, S. F., Hammer, K. A., Naunton, M., … & Cooper, G. M. (2016). Therapeutic potential of tea tree oil for scabies. The American journal of tropical medicine and hygiene, 94(2), 258-266.
• Terpinen-4-ol, a monoterpene alcohol, killed bloodstream forms of the protozoa: T. brucei. From:  Mikus, J., Harkenthal, M., Steverding, D., & Reichling, J. (2000). In vitro effect of essential oils and isolated mono-and sesquiterpenes on Leishmania major and Trypanosoma brucei. Planta Medica, 66(04), 366-368.
• Tea tree oil and terpinen-4-ol were highly effective in reducing the human mite infection: sarcoptes scabiei (scabies).  From:  Walton, S. F., McKinnon, M., Pizzutto, S., Dougall, A., Williams, E., & Currie, B. J. (2004). Acaricidal activity of Melaleuca alternifolia (tea tree) oil: in vitro sensitivity of sarcoptes scabiei var hominis to terpinen-4-ol. Archives of dermatology, 140(5), 563-566.

SKIN / WOUND HEALING / BURNS

• This review of research cited the dermatological uses for tea tree oil. It offers antioxidant, antimicrobial, and anti-inflammatory activities. Its key constituent, terpinen-4-ol, has also exhibited strong antimicrobial and anti-inflammatory actions. Clinical studies have demonstrated the use of tea tree for acne, seborrheic dermatitis, wound healing, and anti-skin cancer activities. From: Pazyar, N., Yaghoobi, R., Bagherani, N., & Kazerouni, A. (2013). A review of applications of tea tree oil in dermatology. International Journal of Dermatology, 52(7), 784-790.
• Tea tree oil reduced wound size in a small study of patients with wounds susceptible to be colonized by MRSA.  From:  Edmondson, M., Newall, N., Carville, K., Smith, J., Riley, T. V., & Carson, C. F. (2011). Uncontrolled, open‐label, pilot study of tea tree (Melaleuca alternifolia) oil solution in the decolonisation of methicillin‐resistant Staphylococcus aureus positive wounds and its influence on wound healing. International wound journal, 8(4), 375-384.
• Scabies is a contagious, parasitic skin disease.  In this review of research, tea tree showed to have anti-parasitic and anti-inflammatory actions against scabies.  More research is warranted.  From:  Thomas, J., Carson, C. F., Peterson, G. M., Walton, S. F., Hammer, K. A., Naunton, M., … & Cooper, G. M. (2016). Therapeutic potential of tea tree oil for scabies. The American journal of tropical medicine and hygiene, 94(2), 258-266.
• This was a review of research on using tea tree oil against the mite that causes demodicosis of the skin.  From:  Lam, N. S. K., Long, X. X., Griffin, R. C., Chen, M. K., & Doery, J. C. (2018). Can the tea tree oil (Australian native plant: Melaleuca alternifolia Cheel) be an alternative treatment for human demodicosis on skin? Parasitology, 1-11.
• Tea tree oil and terpinen-4-ol were highly effective in reducing the human mite infection: Sarcoptes scabiei (scabies).  From:  Walton, S. F., McKinnon, M., Pizzutto, S., Dougall, A., Williams, E., & Currie, B. J. (2004). Acaricidal activity of Melaleuca alternifolia (tea tree) oil: in vitro sensitivity of sarcoptes scabiei var hominis to terpinen-4-ol. Archives of dermatology, 140(5), 563-566.
• A topical gel containing hyaluronic acid with tea tree oil and methyl-sulfonyl-methane reduced haemorrhoid symptoms in a double blind study.  From:  Joksimovic, N., Spasovski, G., Joksimovic, V., Andreevski, V., Zuccari, C., & Omini, C. F. (2012). Efficacy and tolerability of hyaluronic acid, tea tree oil and methyl-sulfonyl-methane in a new gel medical device for treatment of haemorrhoids in a double-blind, placebo-controlled clinical trial. Updates in surgery, 64(3), 195-201.
• In a double blind multicenter study with 117 patients, the nail disease: onyehornycosis was improved with tea tree and clotrimazole.  From:  Buck, D. S. (1994). Comparison of Two Topical Preparations for the Treatment of Onyehornycosis: Melaleuca altemifilia (Tea Tree) Oil and Clotrimazole. The Journal of family practice, 38(6).
• In patients with the toe fungus onychomycosis, 80% were cured with the tea tree and butenafine cream.  From:  Syed, T. A., Qureshi, Z. A., Ali, S. M., Ahmad, S., & Ahmad, S. A. (1999). Treatment of toenail onychomycosis with 2% butenafine and 5% Melaleuca alternifolia (tea tree) oil in cream. Tropical Medicine & International Health, 4(4), 284-287.
• Tea tree oil was effective against Candida skin species in vitro.  From: Mandras, N., Scalas, D., Roana, J., Banche, G., D’Amico, F., Allizond, V., … & Tullio, V. (2017). Comparative effect of tea tree oil and anidulafungin on human polymorphonuclear leukocytes functions against Candida krusei. In 45° Congresso nazionale della Società Italiana di Microbiologia(pp. 119-119). Società Italiana di Microbiologia (SIM).
• A preparation of a 10% tea tree cream and a 5% body wash applied for five days was effective and safe in treating skin lesions infected with MRSA.  From:  Dryden, M. S., Dailly, S., & Crouch, M. (2004). A randomized, controlled trial of tea tree topical preparations versus a standard topical regimen for the clearance of MRSA colonization. Journal of Hospital Infection, 56(4), 283-286.
• Tea tree oil was effective against a broad spectrum of skin bacteria in vitro.  Singh, B. R., Vadhana, P., Bhardwaj, M., Vinodh Kumar, O. R., & Sinha, D. K. (2016). Comparative Antimicrobial Activity of Tea Tree Oil (Melaleuca Oil) and Common Topical Antimicrobials against Bacteria Associated With Wound and Topical Infections. Pharm. Anal. Acta, 7, 513.
• This was a review of the topical uses of tea tree oil.  From:  Crawford, G. H., Sciacca, J. R., & James, W. D. (2004). Tea tree oil: cutaneous effects of the extracted oil of Melaleuca alternifolia. Dermatitis: contact, atopic, occupational, drug, 15(2), 59-66.
• The combination of tea tree oil and tobramycin may be useful in treating infections of the skin and respiratory system.  From:  D’Arrigo, M., Ginestra, G., Mandalari, G., Furneri, P. M., & Bisignano, G. (2010). Synergism and postantibiotic effect of tobramycin and Melaleuca alternifolia (tea tree) oil against Staphylococcus aureus and Escherichia coli. Phytomedicine, 17(5), 317-322.
• In a study of 50 patients with wound ulcers, an herbal ointment was applied twice a day for 28 days. It contained Symphytum officinale, Plantago major, Calendula officinalis, Matricaria chamomilla, Bellis perennis, Achillea millefolium, Salvia officinalis, Hypericum perforatum, Olea europaea, Lavandula officinalis, Melaleuca alternifolia, Cympobogon martini, Origanum vulgare, Eugenia caryophyllata, Thymus vulgaris ct. thymol, Cera alba, honey, and glycerol. Results showed significant healing of wounds. From: Oreščanin, V. (2016). Treatment of pressure ulcers with Bioapifit® wound healing herbal ointment-a preliminary study. IJRDO: J Biol Sci, 2(10), 1-15. 
• In 40 healthy adults, test areas of the back were overexposed to ultraviolet light. A formulation with Aloe vera showed the highest anti-inflammatory effect. Formulations with Chamomilla recutita, Melissa officinalis, Melaleuca alternifolia and Coriandrum sativum showed some anti-inflammatory effect. From: Beikert, F. C., Schönfeld, B. S., Frank, U., & Augustin, M. (2013). Antiinflammatory potential of seven plant extracts in the ultraviolet erythema test. A randomized, placebo-controlled study. Der Hautarzt; Zeitschrift fur Dermatologie, Venerologie, und verwandte Gebiete, 64(1), 40-46.

​ACNE

• In a 30 day study of 60 patients with acne, a cream containing propolis (a product of honey bees), tea tree oil, and aloe vera was better than erythromycin cream in reducing scars, lesions, and acne severity.  From:  Mazzarello, V., Donadu, M. G., Ferrari, M., Piga, G., Usai, D., Zanetti, S., & Sotgiu, M. A. (2018). Treatment of acne with a combination of propolis, tea tree oil, and Aloe vera compared to erythromycin cream: two double-blind investigations. Clinical pharmacology: advances and applications, 10, 175.
• A tea tree product was applied to the face twice daily for 12 weeks by 18 participants.  It resulted in improved skin with no adverse events.  From:  Malhi, H. K., Tu, J., Riley, T. V., Kumarasinghe, S. P., & Hammer, K. A. (2017). Tea tree oil gel for mild to moderate acne; a 12 week uncontrolled, open‐label phase II pilot study. Australasian Journal of Dermatology, 58(3), 205-210.
• A randomized trial of 124 patients with 5% tea-tree oil and 5% benzoyl peroxide had a significant effect in reducing patients’ acne lesions.  From:  Bassett, I. B., Pannowitz, D. L., & Barnetson, R. S. (1990). A comparative study of tea-tree oil versus benzoylperoxide in the treatment of acne. The Medical Journal of Australia, 153(8), 455-458.
• In a review of research for tea tree in the treatment of acne, it was considered effective and well tolerated.  From:  Hammer, K. A. (2015). Treatment of acne with tea tree oil (melaleuca) products: A review of efficacy, tolerability and potential modes of action. International journal of antimicrobial agents, 45(2), 106-110.
• In a double blind clinical study with 60 patients with mild to moderate acne, a solution with 5% tea tree oil was effective in treating acne.  From:  Enshaieh, S., Jooya, A., Siadat, A. H., & Iraji, F. (2007). The efficacy of 5% topical tea tree oil gel in mild to moderate acne vulgaris: a randomized, double-blind placebo-controlled study. Indian Journal of Dermatology, Venereology, and Leprology, 73(1), 22.

DANDRUFF

• Tea tree was effective in vitro agains dandruff fungi.  From: Naveen, S., Karthika, S., Sentila, R., Mahenthiran, R., & Michael, A. (2017). In-vitro evaluation of herbal and chemical agents in the management of dandruff. Journal of Microbiology and Biotechnology Research, 2(6), 916-921.
• In a randomized study of 120 patients with mild to moderate dandruff, a 5% tea tree oil shampoo used daily for 4 weeks significantly reduced dandruff with no adverse side effects.  From: Satchell, A. C., Saurajen, A., Bell, C., & Barnetson, R. S. (2002). Treatment of dandruff with 5% tea tree oil shampoo. Journal of the American Academy of Dermatology, 47(6), 852-855.

ANTI-INFLAMMATORY

• Tea tree oil reduced histamine-induced skin inflammation in humans.  From:  Koh, K. J., Pearce, A. L., Marshman, G., Finlay‐Jones, J. J., & Hart, P. H. (2002). Tea tree oil reduces histamine‐induced skin inflammation. British Journal of Dermatology, 147(6), 1212-1217.
• Tea tree oil and its Terpinen-4-ol constituent showed anti-inflammatory activity.  From:  Hart, P. H., Brand, C., Carson, C. F., Riley, T. V., Prager, R. H., & Finlay-Jones, J. J. (2000). Terpinen-4-ol, the main component of the essential oil of Melaleuca alternifolia (tea tree oil), suppresses inflammatory mediator production by activated human monocytes. Inflammation Research, 49(11), 619-626.
• Anti-inflammatory action of tea tree oil was associated with bactericidal, antioxidant and radical scavenging activity in vitro.  From:  Caldefie-Chezet, F., Guerry, M., Chalchat, J. C., Fusillier, C., Vasson, M. P., & Guillot, J. (2004). Anti-inflammatory effects of Melaleuca alternifolia essential oil on human polymorphonuclear neutrophils and monocytes. Free radical research, 38(8), 805-811.
• Topical tea tree oil and terpinen-4-ol and α-terpineol affected oedema associated with the efferent phase of a contact hypersensitivity response in mice.  From:  Brand, C., Grimbaldeston, M. A., Gamble, J. R., Drew, J., Finlay-Jones, J. J., & Hart, P. H. (2002). Tea tree oil reduces the swelling associated with the efferent phase of a contact hypersensitivity response. Inflammation Research, 51(5), 236-244.
• Tea tree reduced plaque formation and inflammation orally.  From:  Saxer, U. P., Stäuble, A., Szabo, S. H., & Menghini, G. (2003). Effect of mouthwashing with tea tree oil on plaque and inflammation. Schweizer Monatsschrift für Zahnmedizin= Revue mensuelle suisse d’odonto-stomatologie= Rivista mensile svizzera di odontologia e stomatologia/SSO, 113(9), 985.
• Tea tree reduced the inflammation of gingivitis in this double blind study.  From:  Soukoulis, S., & Hirsch, R. (2004). The effects of a tea tree oil‐containing gel on plaque and chronic gingivitis. Australian dental journal, 49(2), 78-83.
• In a study of 16 patients with gingivitis, a tea tree oil mouth rinse reduced inflammation and bacteria.  From:  Salvatori, C., Barchi, L., Guzzo, F., & Gargari, M. (2017). A comparative study of antibacterial and anti-inflammatory effects of mouthrinse containing tea tree oil. ORAL & implantology, 10(1), 59.

ORAL HEALTH

• In this review of research, the author concluded: tea tree oil has anti‐inflammatory and antimicrobial properties which can be applied to the periodontal tissues.  More research is warranted.  From:  Casarin, M., Pazinatto, J., Santos, R. C. V., & Zanatta, F. B. (2018). Melaleuca alternifolia and its application against dental plaque and periodontal diseases: A systematic review. Phytotherapy Research, 32(2), 230-242.
• In a study of 16 patients with gingivitis, a tea tree oil mouth rinse reduced inflammation and bacteria.  From:  Salvatori, C., Barchi, L., Guzzo, F., & Gargari, M. (2017). A comparative study of antibacterial and anti-inflammatory effects of mouthrinse containing tea tree oil. ORAL & implantology, 10(1), 59.
• Tea tree reduced plaque formation and inflammation orally.  From:  Saxer, U. P., Stäuble, A., Szabo, S. H., & Menghini, G. (2003). Effect of mouthwashing with tea tree oil on plaque and inflammation. Schweizer Monatsschrift für Zahnmedizin= Revue mensuelle suisse d’odonto-stomatologie= Rivista mensile svizzera di odontologia e stomatologia/SSO, 113(9), 985.
• An essential oil solution with tea tree, peppermint, and lemon reduced bad breath in patients.  From:  Hur, M. H., Park, J., Maddock‐Jennings, W., Kim, D. O., & Lee, M. S. (2007). Reduction of mouth malodour and volatile sulphur compounds in intensive care patients using an essential oil mouthwash. Phytotherapy Research, 21(7), 641-643.
• Tea tree reduced the inflammation of gingivitis in this double blind study.  From:  Soukoulis, S., & Hirsch, R. (2004). The effects of a tea tree oil‐containing gel on plaque and chronic gingivitis. Australian dental journal, 49(2), 78-83.
• Hospice patients with terminal cancer had improved oral health with using a mixture including geranium, lavender, tea tree, and peppermint.  From:  Kang, H. Y., Na, S. S., & Kim, Y. K. (2010). Effects of Oral Care with Essential Oil on Improvement in Oral Health Status of Hospice Patients. Journal of Korean Academy of Nursing, 40(4).
• Tea tree showed antifungal activity against yeasts from cancer patients’ mouths in vitro.  From:  Bagg, J., Jackson, M. S., Sweeney, M. P., Ramage, G., & Davies, A. N. (2006). Susceptibility to Melaleuca alternifolia (tea tree) oil of yeasts isolated from the mouths of patients with advanced cancer. Oral Oncology, 42(5), 487-492.
• Tea tree oral solution was effective for AIDS patients with oropharyngeal candidiasis refractory to fluconazole.  From:  Jandourek, A., Vaishampayan, J. K., & Vazquez, J. A. (1998). Efficacy of melaleuca oral solution for the treatment of fluconazole refractory oral candidiasis in AIDS patients. Aids, 12(9), 1033-1037.
• Melaleuca oral solutions reduced oropharyngeal candidiasis refractory to fluconazole in AIDS patients. From:  Vazquez, J. A., & Zawawi, A. A. (2002). Efficacy of alcohol-based and alcohol-free melaleuca oral solution for the treatment of fluconazole-refractory oropharyngeal candidiasis in patients with AIDS. HIV clinical trials, 3(5), 379-385.
• M. alternifolia oil mixed with tissue conditioner was effective in treating denture stomatitis.  From:  Catalán, A., Pacheco, J. G., Martínez, A., & Mondaca, M. A. (2008). In vitro and in vivo activity of Melaleuca alternifolia mixed with tissue conditioner on Candida albicans. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 105(3), 327-332.
• Against oral bacteria, Australian tea tree, peppermint, and sage oil as well as the thymol and eugenol constituents were potent.  From:  Shapiro, S., Meier, A., & Guggenheim, B. (1994). The antimicrobial activity of essential oils and essential oil components towards oral bacteria. Oral microbiology and immunology, 9(4), 202-208.
• Manuka and tea tree oil had strong antibacterial activity against pathogenic and cariogenic mouth bacteria.  From:  Takarada, K., Kimizuka, R., Takahashi, N., Honma, K., Okuda, K., & Kato, T. (2004). A comparison of the antibacterial efficacies of essential oils against oral pathogens. Oral microbiology and immunology, 19(1), 61-64.
• Garlic and tea tree oil might be an alternative in fighting oral microbes.  From:  Groppo, F. C., Ramacciato, J. C., Simoes, R. P., Florio, F. M., & Sartoratto, A. (2002). Antimicrobial activity of garlic, tea tree oil, and chlorhexidine against oral microorganisms. International dental journal, 52(6), 433-437.
• A variety of oral bacteria were affected by tea tree.  From:  Hammer, K. A., Dry, L., Johnson, M., Michalak, E. M., Carson, C. F., & Riley, T. V. (2003). Susceptibility of oral bacteria to Melaleuca alternifolia (tea tree) oil in vitro. Oral microbiology and immunology, 18(6), 389-392.
• Tea tree oil showed action against Candida albicans and maybe useful in treating fungal mucosal and cutaneous infections.  From:  D’auria, F. D., Laino, L., Strippoli, V., Tecca, M., Salvatore, G., Battinelli, L., & Mazzanti, G. (2001). In vitro activity of tea tree oil against Candida albicans mycelial conversion and other pathogenic fungi. Journal of chemotherapy, 13(4), 377-383.
• Against the oral bacteria: Streptococcus mutans, Porphyromonas gingivalis, and Lactobacillus rhamnosus, the 13 most effective essential oils were: myrrh, ginger, basil, carrot seed, tea tree, patchouli, ylang ylang, cypress, lemongrass, cinnamon, peppermint, lavender, and eucalyptus. From: Park, C., & Yoon, H. (2018). Antimicrobial Activity of Essential Oil against Oral Strain. International Journal of Clinical Preventive Dentistry, 14(4), 216-221.

ANTI-CANCER

• Tea tree oil and its active component terpinen-4-ol were able to induce apoptosis of human melanoma cells.  From:  Calcabrini, A., Stringaro, A., Toccacieli, L., Meschini, S., Marra, M., Colone, M., … & Mondello, F. (2004). Terpinen-4-ol, the main component of Melaleuca alternifolia (tea tree) oil inhibits the in vitro growth of human melanoma cells. Journal of Investigative Dermatology, 122(2), 349-360.
• Topical tea tree oil reduced tumors in mice.  From:  Ireland, D. J., Greay, S. J., Hooper, C. M., Kissick, H. T., Filion, P., Riley, T. V., & Beilharz, M. W. (2012). Topically applied Melaleuca alternifolia (tea tree) oil causes direct anti-cancer cytotoxicity in subcutaneous tumour bearing mice. Journal of dermatological science, 67(2), 120-129.
• Tea tree oil was active against leukemia cancer cells in vitro.  From:  Byahatti, S., Bogar, C., Bhat, K., & Dandagi, G. (2018). Evaluation of anticancer activity of Melaleuca alternifolia.(ie tea tree oil) on Leukemia cancer cell line (K562): An in vitro study. Journal of Medicinal Plants, 6(5), 01-06.

RESPIRATORY HEALTH

• Inhaling nano-emulsions of tea tree oil reduced bacterial and fungal pneumonia in vivo.  From:  Li, M., Zhu, L., Liu, B., Du, L., Jia, X., Han, L., & Jin, Y. (2016). Tea tree oil nanoemulsions for inhalation therapies of bacterial and fungal pneumonia. Colloids and Surfaces B: Biointerfaces, 141, 408-416.
• The combination of tea tree oil and tobramycin may be useful in treating infections of the skin and respiratory system.  From:  D’Arrigo, M., Ginestra, G., Mandalari, G., Furneri, P. M., & Bisignano, G. (2010). Synergism and postantibiotic effect of tobramycin and Melaleuca alternifolia (tea tree) oil against Staphylococcus aureus and Escherichia coli. Phytomedicine, 17(5), 317-322.

ANTIOXIDANT

• Tea tree oil and its isolated terpenoids showed antioxidant activities.  From:  Kim, H. J., Chen, F., Wu, C., Wang, X., Chung, H. Y., & Jin, Z. (2004). Evaluation of antioxidant activity of Australian tea tree (Melaleuca alternifolia) oil and its components. Journal of agricultural and food chemistry, 52(10), 2849-2854.

ANTIMICROBIAL / ANTIFUNGAL / ANTIBACTERIAL / ANTIVIRAL

• Tea tree has shown activity against the following bacteria in multiple cited studies: Acinetobacter baumannii, Actinomyces viscosus, Actinomyces spp., Bacillus cereus, Bacteroides spp., Corynebacterium sp., Enterococcus faecalis, E. faecium, Escherichia coli, Fusobacterium nuicleatujm, Klebsiella pneumoniae, Lactobacillus sppl, Micrococcus luteus, Peptostreptococcus anaerobius, Porphyromonas endodentalis, P. gingivalis, Prevotella spp., P. intermedia, Propionibacterium acnes, Proteus vulgaris, Pseudomonas aeruginosa, Staphylococcus aureus, S. epidermidis, S. hominis, S. pyogenes, and Veillonella spp.  From:  Carson, C. F., Hammer, K. A., & Riley, T. V. (2006). Melaleuca alternifolia (tea tree) oil: a review of antimicrobial and other medicinal properties. Clinical microbiology reviews, 19(1), 50-62.
• Tea tree oil was antimicrobial against multiple tested pathogenic bacteria.  Mumu, S. K., & Hossain, M. M. (2018). Antimicrobial activity of tea tree oil against pathogenic bacteria and comparison of its effectiveness with eucalyptus oil, lemongrass oil and conventional antibiotics. American Journal of Microbiological Research, 6(3), 73-78.
• Tea tree oil demonstrates broad spectrup antimicrobial activity against gram negative bacteria: E. coli, gram positive bacteria: Staph. aureus, and Candida albicans by disrupting  the permeability barrier of microbial cell membranes.  From:  Cox, S. D., Mann, C. M., Markham, J. L., Bell, H. C., Gustafson, J. E., Warmington, J. R., & Wyllie, S. G. (2000). The mode of antimicrobial action of the essential oil of Melaleuca alternifolia (tea tree oil). Journal of applied microbiology, 88(1), 170-175.
• ​Tea tree has shown activity against the following fungi in multiple cited studies: Alternaria spp., Aspergillus flavus, A. funigatus, A. niger, Blastoschizomyces capitanis, Candida albicans, C. glabrata, C. parapsilosis, C. tropicalis, Cladosporium spp., Cryptococcus neoformans, Epidermophyton flocossum, Fusarium spp.,k Malassezia furfur, M. sympodialis, Microsporum canis, M. gypseu8m, Penicillium spp., Rhodotorula rubra, Saccharomyces cerevisiae, Trichophyton mentagrpphytes, T. rubrum, T. tonsurans, and Trichosporon spp.   From:  Carson, C. F., Hammer, K. A., & Riley, T. V. (2006). Melaleuca alternifolia (tea tree) oil: a review of antimicrobial and other medicinal properties. Clinical microbiology reviews, 19(1), 50-62.
• A preparation with tea tree was effective and safe in treating skin lesions of MRSA.  From:  Dryden, M. S., Dailly, S., & Crouch, M. (2004). A randomized, controlled trial of tea tree topical preparations versus a standard topical regimen for the clearance of MRSA colonization. Journal of Hospital Infection, 56(4), 283-286.
• The study showed antimicrobial activity of tea tree oil resulted from interrupting the permeability barrier in the microbes: E. coli, Staph. aureus and C. albicans.  From:  Cox, S. D., Mann, C. M., Markham, J. L., Bell, H. C., Gustafson, J. E., Warmington, J. R., & Wyllie, S. G. (2000). The mode of antimicrobial action of the essential oil of Melaleuca alternifolia (tea tree oil). Journal of applied microbiology, 88(1), 170-175.
• Tea tree oil was effective against Candida skin species in vitro.  From: Mandras, N., Scalas, D., Roana, J., Banche, G., D’Amico, F., Allizond, V., … & Tullio, V. (2017). Comparative effect of tea tree oil and anidulafungin on human polymorphonuclear leukocytes functions against Candida krusei. In 45° Congresso nazionale della Società Italiana di Microbiologia(pp. 119-119). Società Italiana di Microbiologia (SIM).
• Tea tree and lavender oil combined synergistically were effective against the following fungi:  Trichophyton rubrum and T. mentagrophytes var. interdigitale. From:  Cassella, S., Cassella, J. P., & Smith, I. (2002). Synergistic antifungal activity of tea tree (Melaleuca alternifolia) and lavender (Lavandula angustifolia) essential oils against dermatophyte infection. International Journal of Aromatherapy, 12(1), 2-15.
• M. alternifolia oil mixed with tissue conditioner was effective in treating denture stomatitis.  From:  Catalán, A., Pacheco, J. G., Martínez, A., & Mondaca, M. A. (2008). In vitro and in vivo activity of Melaleuca alternifolia mixed with tissue conditioner on Candida albicans. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 105(3), 327-332.
• This study described the antibacterial activity of tea tree oil and terpinen-4-ol against Staphylococcus aureus.  From:  Cuaron, J. A., Dulal, S., Song, Y., Singh, A. K., Montelongo, C. E., Yu, W., … & Gustafson, J. E. (2013). Tea Tree Oil‐Induced Transcriptional Alterations in Staphylococcus aureus. Phytotherapy Research, 27(3), 390-396.
• Tea tree oil showed action against Candida albicans and maybe useful in treating fungal mucosal and cutaneous infections.  From:  D’auria, F. D., Laino, L., Strippoli, V., Tecca, M., Salvatore, G., Battinelli, L., & Mazzanti, G. (2001). In vitro activity of tea tree oil against Candida albicans mycelial conversion and other pathogenic fungi. Journal of chemotherapy, 13(4), 377-383.
• This article summarized antimicrobial research on essential oils with strong research on topical and antiseptic uses, as penetration enhancers, and in fighting medicine resistant species.  From:  Solórzano-Santos, F., & Miranda-Novales, M. G. (2012). Essential oils from aromatic herbs as antimicrobial agents. Current opinion in biotechnology, 23(2), 136-141.
• Tea tree has shown antiviral activity in multiple studies against the following:  the tobacco mosaic virus, herpes simplex virus and both enveloped and nonenveloped viruses.  From:  From:  Carson, C. F., Hammer, K. A., & Riley, T. V. (2006). Melaleuca alternifolia (tea tree) oil: a review of antimicrobial and other medicinal properties. Clinical microbiology reviews, 19(1), 50-62.
• Inhibition of 45 oils on eight bacteria (four Gram positive and four Gram negative), two fungi, and one yeast were examined using disk assay.  Cinnamomum zeylanicum and Melaleuca alternifolia showed an inhibition against all test organisms and phage. Coriandrum sativum highly inhibited Gram positive bacteria and fungi. Cymbopogon flexuosus and Chamaemelum nobile oils highly inhibited both phage types. Angelica archangelica and Pinus sylvestris inhibited bacteria, but not any fungi. Oils with the highest antimicrobial abilities with the broadest range of inhibition were cinnamon bark (Cinnamomum zeylanicum), lemongrass (Cymbopogon flexuosus), savory (Satureja montana), Roman chamomile (Cbamaemelum nobile), rosewood (Aniba rosaeodora), spearmint (Mentha spicata) and tea tree (Melaleuca alternifolia).  From:  Chao, S. C., Young, D. G., & Oberg, C. J. (2000). Screening for inhibitory activity of essential oils on selected bacteria, fungi and viruses. Journal of Essential Oil Research, 12(5), 639-649.
• Tea tree oil and its components, 1,8-cineole, terpinen-4-ol, and α-terpineol demonstrated activity against Staphylococcus aureus.  From: Carson, C. F., Mee, B. J., & Riley, T. V. (2002). Mechanism of action of Melaleuca alternifolia (tea tree) oil on Staphylococcus aureus determined by time-kill, lysis, leakage, and salt tolerance assays and electron microscopy. Antimicrobial agents and chemotherapy, 46(6), 1914-1920.
• The combination of tea tree oil and tobramycin may be useful in treating infections of the skin and respiratory system.  From:  D’Arrigo, M., Ginestra, G., Mandalari, G., Furneri, P. M., & Bisignano, G. (2010). Synergism and postantibiotic effect of tobramycin and Melaleuca alternifolia (tea tree) oil against Staphylococcus aureus and Escherichia coli. Phytomedicine, 17(5), 317-322.
• Tea tree oil and its terpinen-4-ol constituent showed strong antimicrobial activity against tested pathogens.  From: Carson, C. F., & Riley, T. V. (1995). Antimicrobial activity of the major components of the essential oil of Melaleuca alternifolia. Journal of applied bacteriology, 78(3), 264-269.
• Orange, eucalyptus, fennel, geranium, juniper, peppermint, rosemary, purified turpentine, thyme, and Australian tea tree oil as well as the constituent of menthol showed antimicrobial and antiplasmid activities against the bacteria tested.  From:  Schelz, Z., Molnar, J., & Hohmann, J. (2006). Antimicrobial and antiplasmid activities of essential oils. Fitoterapia, 77(4), 279-285.
• Against oral bacteria, Australian tea tree, peppermint, and sage oil as well as the thymol and eugenol constituents were potent.  From:  Shapiro, S., Meier, A., & Guggenheim, B. (1994). The antimicrobial activity of essential oils and essential oil components towards oral bacteria. Oral microbiology and immunology, 9(4), 202-208.
• Thyme, origanum, clove, and orange essential oils were the most inhibitory against foodborne bacteria and yeasts. Cumin, tea tree, and mint also provided inhibition.  From:  Irkin, R., & Korukluoglu, M. (2009). Growth inhibition of pathogenic bacteria and some yeasts by selected essential oils and survival of L. monocytogenes and C. albicans in apple–carrot juice. Foodborne pathogens and disease, 6(3), 387-394.
• Oregano, thyme, cinnamon bark, lemongrass, clove, palmarose, peppermint, lavender, geranium, Bourbon, and tea tree reduced fungus in heated footbath water.  From:  Inouye, S., Uchida, K., Nishiyama, Y., Hasumi, Y., Yamaguchi, H., & Abe, S. (2007). Combined effect of heat, essential oils and salt on the fungicidal activity against Trichophyton mentagrophytes in foot bath. Nippon Ishinkin Gakkai Zasshi, 48(1), 27-36.
• A mix of tea tree, niaouli, and beta triketones from melaleuca were effective against Staphylococcus aureus and Moraxella catarrhalis.  From:  Christoph, F., Kaulfers, P. M., & Stahl-Biskup, E. (2001). In vitro evaluation of the antibacterial activity of β-triketones admixed to Melaleuca oils. Planta medica, 67(08), 768-771.
• Rosmarinus officinalis, Mentha piperita and Melaleuca alternifolia inhibited Listeria monocytogenes growth.  From:  Sandasi, M., Leonard, C. M., & Viljoen, A. M. (2010). The in vitro antibiofilm activity of selected culinary herbs and medicinal plants against Listeria monocytogenes. Letters in applied microbiology, 50(1), 30-35.
• Antibacterial activity of Australian tea tree, cajuput, niaouli, kanuka, manuka, and eucalyptus oil were assessed.  From:  Harkenthal, M., Reichling, J., Geiss, H. K., & Saller, R. (1999). Comparative study on the in vitro antibacterial activity of Australian tea tree oil, cajuput oil, niaouli oil, manuka oil, kanuka oil, and eucalyptus oil. Die Pharmazie, 54(6), 460-463.
• The antimicrobial activity of twenty-seven essential oils were tested, especially against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa.  The S. aureus strains were highly susceptible to Piper nigrum (black pepper) and Melaleuca alternifolia (tea tree).  The following were effective against E. coli:Copaifera officinalis, Cinnamomum cassia (cinnamon), and Syzygium aromaticum (clove). Clove was also strong against P. aeruginosa.  From:  Murbach Teles Andrade, B. F., Nunes Barbosa, L., da Silva Probst, I., & Fernandes Júnior, A. (2014). Antimicrobial activity of essential oils. Journal of Essential Oil Research, 26(1), 34-40.
• Lavender and tea tree showed antifungal activity against T. rubrum.  From:  Cassella, J. P., Cassella, S., Ashford, R., & Siddals, E. (2001). Antifungal activity of tea tree and lavender essential oils in the treatment of Trichophyton rubrum infection. Focus on Alternative and Complementary Therapies, 6(1), 74-74.
• Klebsiella pneumoniae was highly sensitive to terpinen-4-ol and geraniol was likely the active antibacterial constituent of C. martinii EO.  Melaleuca alternifolia (tea tree), Pelargonium graveolens (geranium) and Cymbopogon martinii (lemongrass) were three essential oils tested, with these constituents.  From:  Murbach Teles Andrade, B. F., Nunes Barbosa, L., Bérgamo Alves, F. C., Albano, M., Mores Rall, V. L., Sforcin, J. M., … & Fernandes Júnior, A. (2016). The antibacterial effects of Melaleuca alternifolia, Pelargonium graveolens and Cymbopogon martinii essential oils and major compounds on liquid and vapor phase. Journal of Essential Oil Research, 28(3), 227-233.
• Hospice patients with terminal cancer had improved oral health with using a mixture including geranium, lavender, tea tree, and peppermint.  From:  Kang, H. Y., Na, S. S., & Kim, Y. K. (2010). Effects of Oral Care with Essential Oil on Improvement in Oral Health Status of Hospice Patients. Journal of Korean Academy of Nursing, 40(4)
• In a study of 30 different vaginal isolated strains of C. albicans to twelve essential oils, compared to the three of the mainly used drugs (clotrimazole, fluconazole, itraconazole), mint, basil, lavender, tea tree oil, winter savory and oregano essential oils inhibited both the growth and the activity of C. albicans more efficiently than clotrimazole.  From:  Bona, E., Cantamessa, S., Pavan, M., Novello, G., Massa, N., Rocchetti, A., … & Gamalero, E. (2016). Sensitivity of Candida albicans to essential oils: are they an alternative to antifungal agents?. Journal of Applied Microbiology.
• Tea tree oil was effective against vaginal Candida ssp. In vitro.  From:  Di Vito, M., Mattarelli, P., Modesto, M., Girolamo, A., Ballardini, M., Tamburro, A., … & Mondello, F. (2015). In vitro activity of tea tree oil vaginal suppositories against Candida spp. and probiotic vaginal microbiota. Phytotherapy Research, 29(10), 1628-1633.
• Tea tree, lavender, mint, thyme, and juniper showed varying degrees of in-vitro action against S. aureus.  From:  Nelson, R. R. (1997). In-vitro activities of five plant essential oils against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium. Journal of Antimicrobial Chemotherapy, 40(2), 305-306.
• Cedrus atlantica (cedarwood), Styrax tonkinensis (benzoin resinoid) , Juniperus communis (juniper) , Lavandula angustifolia (lavender) , Melaleuca alternifolia (tea tree), Pelargonium graveolens (geranium), Pogestemon patchouli (patchouli) and Rosmarinus officinalis (rosemary) as well as the constituents geraniol and citronellol were analyzed for antifungal activities against Aspergillus niger and A. flavus. Most of the tested essential oils, except not C. atlantica, J. communis, and P. patchouli, showed significantly inhibited growth, and geraniol and citronellol, exhibited additive effects.  From:  Shin, S. (2003). Anti-Aspergillus activities of plant essential oils and their combination effects with ketoconazole or amphotericin B. Archives of pharmacal research, 26(5), 389-393.
• Origanum vulgare (oregano), Thymus vulgaris (thyme), Lavandula angustifolia (lavender) , Mentha piperita (peppermint), and Melaleuca alternifolia (tea tree) were tested against 32 erythromycin-resistant streptococci; oregano, thyme, and the carvacrol constituent showed the strongest antimicrobial activity.  From:  Magi, G., Marini, E., & Facinelli, B. (2015). Antimicrobial activity of essential oils and carvacrol, and synergy of carvacrol and erythromycin, against clinical, erythromycin-resistant Group A Streptococci. Frontiers in microbiology, 6, 165.
• Manuka and tea tree oil had strong antibacterial activity against pathogenic and cariogenic mouth bacteria.  From:  Takarada, K., Kimizuka, R., Takahashi, N., Honma, K., Okuda, K., & Kato, T. (2004). A comparison of the antibacterial efficacies of essential oils against oral pathogens. Oral microbiology and immunology, 19(1), 61-64.
• Garlic and tea tree oil might be an alternative in fighting oral microbes.  From:  Groppo, F. C., Ramacciato, J. C., Simoes, R. P., Florio, F. M., & Sartoratto, A. (2002). Antimicrobial activity of garlic, tea tree oil, and chlorhexidine against oral microorganisms. International dental journal, 52(6), 433-437.
• Plant oils of 52 species were tested against key bacteria.  Lemongrass, oregano and bay inhibited all organisms, and rosewood, coriander, palmarosa, tea tree, niaouli, peppermint, spearmint, sage and marjoram inhibited all organisms except P. aeruginosa.  Carrot, patchouli, sandalwood and vetiver inhibited Gram-positive bacteria and C. albicans. Myrrh and cypress inhibited only Gram-positive organisms and mandarin oil inhibited only C. albicans.  From:  Hammer, K. A., Carson, C. F., & Riley, T. V. (1999). Antimicrobial activity of essential oils and other plant extracts. Journal of applied microbiology, 86(6), 985-990.
• Tea tree oil was especially antifungal against candida spp. From:  Hammer, K. A., Carson, C. F., & Riley, T. V. (1998). In-vitro activity of essential oils, in particular Melaleuca alternifolia (tea tree) oil and tea tree oil products, against Candida spp. Journal of Antimicrobial Chemotherapy, 42(5), 591-595.
• Eucalyptus and tea tree showed an antibacterial effect against MRSA.  From:  Sherry, E., Boeck, H., & Warnke, P. H. (2001). Percutaneous treatment of chronic MRSA osteomyelitis with a novel plant-derived antiseptic. BMC surgery, 1(1), 1.
• In a double blind study, tea tree may have reduced the recurrent herpes labialis virus (RHL) or cold sores but further research is necessary.  From:  Carson, C. F., Ashton, L., Dry, L., Smith, D. W., & Riley, T. V. (2001). Melaleuca alternifolia (tea tree) oil gel (6%) for the treatment of recurrent herpes labialis. Journal of Antimicrobial Chemotherapy, 48(3), 450-451.
• Melaleuca alternifolia, Thymus vulgaris, Mentha piperita and Rosmarinus officinalis were combined with conventional antimicrobials and assessed.  From:  Van Vuuren, S. F., Suliman, S., & Viljoen, A. M. (2009). The antimicrobial activity of four commercial essential oils in combination with conventional antimicrobials. Letters in applied microbiology, 48(4), 440-446.
• Salad preservation was lengthened with the essential oils of thyme verbena, thyme, oregano, ajowan, tea tree, clove, sage, and rosemary.  From:  Molinos, A. C., Abriouel, H., López, R. L., Omar, N. B., Valdivia, E., & Gálvez, A. (2009). Enhanced bactericidal activity of enterocin AS-48 in combination with essential oils, natural bioactive compounds and chemical preservatives against Listeria monocytogenes in ready-to-eat salad. Food and Chemical Toxicology, 47(9), 2216-2223.
• Antimicrobial activity of manuka, kanuka, and tea tree were assessed. From:  Lis‐Balchin, M., Hart, S. L., & Deans, S. G. (2000). Pharmacological and antimicrobial studies on different tea‐tree oils (Melaleuca alternifolia, Leptospermum scoparium or Manuka and Kunzea ericoides or Kanuka), originating in Australia and New Zealand. Phytotherapy research, 14(8), 623-629.
• The following commercially bought oils showed antimicrobial activity against multiple pathogens:  patchouli (Pogostemon cablin), myrrh (Commiphora myrrha), bergamot (Citrus bergamia), geranium (Geranium maculatum), sandalwood (Santalum album), ylang ylang (Cananga odorata), tea tree (Melaleuca alternifolia), and lavender (Lavendula officinalis).   From:  Maudsley, F., & Kerr, K. G. (1999). Microbiological safety of essential oils used in complementary therapies and the activity of these compounds against bacterial and fungal pathogens. Supportive care in cancer, 7(2), 100-102
• Tea tree oil was antifungal against Candida albicans, Candida glabrata and Saccharomyces cerevisiae. From:  Hammer, K. A., Carson, C. F., & Riley, T. V. (2004). Antifungal effects of Melaleuca alternifolia (tea tree) oil and its components on Candida albicans, Candida glabrata and Saccharomyces cerevisiae. Journal of Antimicrobial Chemotherapy, 53(6), 1081-1085.
• Melaleuca alternifolia, Melaleuca quinquenervia and Backhousia citriodora showed antifungal activity against Aspergillus niger and Aspergillus carbonarius in vitro.  From:  de Andrade Santiago, J., das Graças Cardoso, M., Batista, L. R., Santiago, W. D., Passamani, F. R. F., Rodrigues, L. M. A., & Nelson, D. L. (2018). Effect of the essential oils from Melaleuca alternifolia, Melaleuca quinquenervia and Backhousia citriodora on the synthesis of ochratoxin A by Aspergillus niger and Aspergillus carbonarius isolated from tropical wine grapes. Journal of food science and technology, 55(1), 418-423.
• Tea tree oil demonstrated action against Staphylococcus aureus.  From:  Caelli, M., Porteous, J., Carson, C. F., Heller, R., & Riley, T. V. (2001). Tea tree oil as an alternative topical decolonization agent for methicillin-resistant Staphylococcus aureus. International Journal of Aromatherapy, 11(2), 97-99.
• Terpinen-4-ol was active against candida species in the rat vagina.  From:  Mondello, F., De Bernardis, F., Girolamo, A., Cassone, A., & Salvatore, G. (2006). In vivo activity of terpinen-4-ol, the main bioactive component of Melaleuca alternifolia Cheel (tea tree) oil against azole-susceptible and-resistant human pathogenic Candida species. BMC infectious diseases, 6(1), 158.
• Tea tree oil and its terpinen-4-ol constituent were antiviral against influenza.  From:  Garozzo, A., Timpanaro, R., Bisignano, B., Furneri, P. M., Bisignano, G., & Castro, A. (2009). In vitro antiviral activity of Melaleuca alternifolia essential oil. Letters in applied microbiology, 49(6), 806-808.
• The study suggested tea tree’s antiviral activity against influenza was related to the inhibition of uncoating.  From:  Garozzo, A., Timpanaro, R., Stivala, A., Bisignano, G., & Castro, A. (2011). Activity of Melaleuca alternifolia (tea tree) oil on Influenza virus A/PR/8: study on the mechanism of action. Antiviral research, 89(1), 83-88.
• Antimicrobial activity of tea tree oil against Malassezia species was assessed. From:  Hammer, K. A., Carson, C. F., & Riley, T. V. (2000). In vitro activities of ketoconazole, econazole, miconazole, and Melaleuca alternifolia (tea tree) oil against Malassezia species. Antimicrobial agents and chemotherapy, 44(2), 467-469.
• Tea tree oil was inhibitory against a variety of fungi tested.  From:  Hammer, K. A., Carson, C. F., & Riley, T. V. (2002). In vitro activity of Melaleuca alternifolia (tea tree) oil against dermatophytes and other filamentous fungi. Journal of Antimicrobial Chemotherapy, 50(2), 195-199.
• Tea tree oil’s antifungal action was related to compromising membrane function.  From:  Hammer, K. A., Carson, C. F., & Riley, T. V. (2004). Antifungal effects of Melaleuca alternifolia (tea tree) oil and its components on Candida albicans, Candida glabrata and Saccharomyces cerevisiae. Journal of Antimicrobial Chemotherapy, 53(6), 1081-1085.
• A variety of oral bacteria were affected by tea tree.  From:  Hammer, K. A., Dry, L., Johnson, M., Michalak, E. M., Carson, C. F., & Riley, T. V. (2003). Susceptibility of oral bacteria to Melaleuca alternifolia (tea tree) oil in vitro. Oral microbiology and immunology, 18(6), 389-392.
• Tea tree oral solution was effective for AIDS patients with oropharyngeal candidiasis refractory to fluconazole.  From:  Jandourek, A., Vaishampayan, J. K., & Vazquez, J. A. (1998). Efficacy of melaleuca oral solution for the treatment of fluconazole refractory oral candidiasis in AIDS patients. Aids, 12(9), 1033-1037.
• Melaleuca oral solutions reduced oropharyngeal candidiasis refractory to fluconazole in AIDS patients. From:  Vazquez, J. A., & Zawawi, A. A. (2002). Efficacy of alcohol-based and alcohol-free melaleuca oral solution for the treatment of fluconazole-refractory oropharyngeal candidiasis in patients with AIDS. HIV clinical trials, 3(5), 379-385.
• Essential oils from eucalyptus, tea tree, and thyme, and their isolated constituents showed antiviral activity against herpes in vitro.  From:  Astani, A., Reichling, J., & Schnitzler, P. (2010). Comparative study on the antiviral activity of selected monoterpenes derived from essential oils. Phytotherapy Research: An International Journal Devoted to Pharmacological and Toxicological Evaluation of Natural Product Derivatives, 24(5), 673-679.
• Australian tea tree oil, cajuput, niaouli, lema, kanuka, and manuka showed antimicrobial activities against Staphylococcus aureus.  From:  Christoph, F., Stahl-Biskup, E., & Kaulfers, P. M. (2001). Death kinetics of Staphylococcus aureus exposed to commercial tea tree oils sl. Journal of Essential Oil Research, 13(2), 98-102.
• Antimicrobial activities of lavender, thyme, peppermint, cajeput, cinnamon, clove, eucalyptus, sage, and tea tree were summarized.  From:  Wińska, K., Mączka, W., Łyczko, J., Grabarczyk, M., Czubaszek, A., & Szumny, A. (2019). Essential Oils as Antimicrobial Agents—Myth or Real Alternative?. Molecules, 24(11), 2130.
• Tea tree oil reduced symptoms of tinea pedis.  From:  Tong, M. M., Altman, P. M., & Barnetson, R. S. (1992). Tea tree oil in the treatment of tinea pedis. Australasian Journal of Dermatology, 33(3), 145-149.
• Tea tree oil reduced oral microorganisms.  From:  Kulik, E., Lenkeit, K., & Meyer, J. (1999). Antimicrobial effects of tea tree oil (Melaleuca alternifolia) on oral microorganisms. Schweizer Monatsschrift fur Zahnmedizin= Revue mensuelle suisse d’odonto-stomatologie= Rivista mensile svizzera di odontologia e stomatologia, 110(11), 125-130.
• In a double blind study, tea tree oil at 25% and 50% dilution reduced athlete’s foot; four patients had a dermatitis reaction that stopped when the oil was no longer applied.  From:  Satchell, A. C., Saurajen, A., Bell, C., & Barnetson, R. S. (2002). Treatment of interdigital tinea pedis with 25% and 50% tea tree oil solution: A randomized, placebo‐controlled, blinded study. Australasian journal of dermatology, 43(3), 175-178.
• Tea tree oil efficiently killed S. aureus in the stationary growth phase in biofilms.  From:  Kwieciński, J., Eick, S., & Wójcik, K. (2009). Effects of tea tree (Melaleuca alternifolia) oil on Staphylococcus aureus in biofilms and stationary growth phase. International journal of antimicrobial agents, 33(4), 343-347.
• Lysostaphin and tea tree oil showed action against methicillin resistant S. aureus.  From:  LaPlante, K. L. (2007). In vitro activity of lysostaphin, mupirocin, and tea tree oil against clinical methicillin-resistant Staphylococcus aureus. Diagnostic microbiology and infectious disease, 57(4), 413-418.
• This was a review of research on fungal treatments including tea tree, solanum species, and bitter orange oil.  From:  Martin, K. W., & Ernst, E. (2004). Herbal medicines for treatment of fungal infections: a systematic review of controlled clinical trials. Mycoses, 47(3‐4), 87-92.
• In a child, tea tree oil was effective against hand warts due to the human papilloma virus.  From:  Millar, B. C., & Moore, J. E. (2008). Successful topical treatment of hand warts in a paediatric patient with tea tree oil (Melaleuca alternifolia). Complementary therapies in clinical practice, 14(4), 225-227.
• Tea tree oil was effective against tested fungi including C. albicans.  From:  Mondello, F., De Bernardis, F., Girolamo, A., Salvatore, G., & Cassone, A. (2003). In vitro and in vivo activity of tea tree oil against azole-susceptible and-resistant human pathogenic yeasts. Journal of Antimicrobial Chemotherapy, 51(5), 1223-1229.
• Antifungal activity of tea tree oil was demonstrated in vitro.  From:  Nenoff, P., Haustein, U. F., & Brandt, W. (1996). Antifungal activity of the essential oil of Melaleuca alternifolia (tea tree oil) against pathogenic fungi in vitro. Skin Pharmacology and Physiology, 9(6), 388-394.
• Tree tree oil and its terpinen-4-ol constituent were antifungal against multiple tested organisms.   From:  Oliva, B., Piccirilli, E., Ceddia, T., Pontieri, E., Aureli, P., & Ferrini, A. M. (2003). Antimycotic activity of Melaleuca alternifolia essential oil and its major components. Letters in applied microbiology, 37(2), 185-187.
• Garlic and tea tree were effective against oral microorganisms.  From:  Groppo, F. C., Ramacciato, J. C., Simoes, R. P., Florio, F. M., & Sartoratto, A. (2002). Antimicrobial activity of garlic, tea tree oil, and chlorhexidine against oral microorganisms. International dental journal, 52(6), 433-437.
• Polytoxinol, a formula containing tea tree and eucalyptus, was successful in an administered percutaneously treat of intractable MRSA infection of the lower tibia in an adult male.  From:  Sherry, E., Boeck, H., & Warnke, P. H. (2001). Percutaneous treatment of chronic MRSA osteomyelitis with a novel plant-derived antiseptic. BMC surgery, 1(1), 1.
• Tea tree oil was active against Madurella mycetomatis (Madura foot). From:  van de Sande, W. W., Fahal, A. H., Riley, T. V., Verbrugh, H., & van Belkum, A. (2007). In vitro susceptibility of Madurella mycetomatis, prime agent of Madura foot, to tea tree oil and artemisinin. Journal of antimicrobial chemotherapy, 59(3), 553-555.
• Commercial tea tree oil demonstrated antifungal activity in vitro.  From:  Thomsen, P. S., Jensen, T. M., Hammer, K. A., Carson, C. F., Mølgaard, P., & Riley, T. V. (2011). Survey of the antimicrobial activity of commercially available Australian tea tree (Melaleuca alternifolia) essential oil products in vitro. The Journal of Alternative and Complementary Medicine, 17(9), 835-841.
• Tea tree oil was effective against a broad spectrum of skin bacteria in vitro.  Singh, B. R., Vadhana, P., Bhardwaj, M., Vinodh Kumar, O. R., & Sinha, D. K. (2016). Comparative Antimicrobial Activity of Tea Tree Oil (Melaleuca Oil) and Common Topical Antimicrobials against Bacteria Associated With Wound and Topical Infections. Pharm. Anal. Acta, 7, 513.
• Against the oral bacteria: Streptococcus mutans, Porphyromonas gingivalis, and Lactobacillus rhamnosus, the 13 most effective essential oils were: myrrh, ginger, basil, carrot seed, tea tree, patchouli, ylang ylang, cypress, lemongrass, cinnamon, peppermint, lavender, and eucalyptus. From: Park, C., & Yoon, H. (2018). Antimicrobial Activity of Essential Oil against Oral Strain. International Journal of Clinical Preventive Dentistry, 14(4), 216-221.
• The antimicrobial activites of Melaleuca spp is reviewed. From: Sharifi‐Rad, J., Salehi, B., Varoni, E. M., Sharopov, F., Yousaf, Z., Ayatollahi, S. A., … & Iriti, M. (2017). Plants of the Melaleuca genus as antimicrobial agents: From farm to pharmacy. Phytotherapy Research, 31(10), 1475-1494.
• Clove, cajeput, tea tree, naiouli, and eucalyptus showed varying degrees of activity against Penicillium commune. From: Tančinová, D., Foltinová, D., Mašková, Z., Štefániková, J., & Árvay, J. (2019). Effect of essential oils of Myrtaceae plants on the Penicillium commune. Potravinarstvo Slovak Journal of Food Sciences, 13(1), 604-613.
• Tea tree essential oil showed antiviral influenza activity in vitro, inhibiting entry into host cells. From: Li, X., Duan, S., Chu, C., Xu, J., Zeng, G., Lam, A. K. Y., … & Gu, H. (2013). Melaleuca alternifolia concentrate inhibits in vitro entry of influenza virus into host cells. Molecules, 18(8), 9550-9566.
• Tea tree and eucalyptus essential oil aerosol and vapours cleared 95% of influenza A virus and E. coli phage M13 within 5 – 15 minutes of exposure. From: Usachev, E. V., Pyankov, O. V., Usacheva, O. V., & Agranovski, I. E. (2013). Antiviral activity of tea tree and eucalyptus oil aerosol and vapour. Journal of aerosol science, 59, 22-30.

ATLETE’S FOOT

• In a randomized double blind study (104 patients), tea tree oil was as effective as tolfonate in reducing symptoms of tinea pedis.  From:  Tong, M. M., Altman, P. M., & Barnetson, R. S. (1992). Tea tree oil in the treatment of tinea pedis. Australasian Journal of Dermatology, 33(3), 145-149
• In a randomized, controlled, double blind study of tea tree oil in treating 158 patients with athlete’s foot; there was a cure rate of 64% after four weeks of applying a 50% solution twice a day; four patients had a dermatitis reaction that stopped when the oil was no longer applied.  From:  Satchell, A. C., Saurajen, A., Bell, C., & Barnetson, R. S. (2002). Treatment of interdigital tinea pedis with 25% and 50% tea tree oil solution: A randomized, placebo‐controlled, blinded study. Australasian journal of dermatology, 43 (3), 175-178.
• Tea tree oil reduced symptoms of tinea pedis.  From:  Tong, M. M., Altman, P. M., & Barnetson, R. S. (1992). Tea tree oil in the treatment of tinea pedis. Australasian Journal of Dermatology, 33(3), 145-149.
• In a double blind study, tea tree oil at 25% and 50% dilution reduced athlete’s foot; four patients had a dermatitis reaction that stopped when the oil was no longer applied.  From:  Satchell, A. C., Saurajen, A., Bell, C., & Barnetson, R. S. (2002). Treatment of interdigital tinea pedis with 25% and 50% tea tree oil solution: A randomized, placebo‐controlled, blinded study. Australasian journal of dermatology, 43(3), 175-178.
• In a double blind multicenter study with 117 patients, the nail disease: onyehornycosis was improved with tea tree and clotrimazole.  From:  Buck, D. S. (1994). Comparison of Two Topical Preparations for the Treatment of Onyehornycosis: Melaleuca altemifilia (Tea Tree) Oil and Clotrimazole. The Journal of family practice, 38(6).
• In patients with the toe fungus onychomycosis, 80% were cured with the tea tree and butenafine cream.  From:  Syed, T. A., Qureshi, Z. A., Ali, S. M., Ahmad, S., & Ahmad, S. A. (1999).
• Tea tree oil showed action against Candida albicans and maybe useful in treating fungal mucosal and cutaneous infections.  From:  D’auria, F. D., Laino, L., Strippoli, V., Tecca, M., Salvatore, G., Battinelli, L., & Mazzanti, G. (2001). In vitro activity of tea tree oil against Candida albicans mycelial conversion and other pathogenic fungi. Journal of chemotherapy, 13(4), 377-383.
• Oregano, thyme, cinnamon bark, lemongrass, clove, palmarose, peppermint, lavender, geranium, Bourbon, and tea tree reduced fungus in heated footbath water.  From:  Inouye, S., Uchida, K., Nishiyama, Y., Hasumi, Y., Yamaguchi, H., & Abe, S. (2007). Combined effect of heat, essential oils and salt on the fungicidal activity against Trichophyton mentagrophytes in foot bath. Nippon Ishinkin Gakkai Zasshi, 48(1), 27-36.

MOUTH COLD SORES

• In a double blind study, tea tree may have reduced the recurrent herpes labialis virus (RHL) or cold sores but further research is necessary.  From:  Carson, C. F., Ashton, L., Dry, L., Smith, D. W., & Riley, T. V. (2001). Melaleuca alternifolia (tea tree) oil gel (6%) for the treatment of recurrent herpes labialis. Journal of Antimicrobial Chemotherapy, 48(3), 450-451.

​PRESERVATIVE

• Thyme, origanum, clove, and orange essential oils were the most inhibitory against foodborne bacteria and yeasts. Cumin, tea tree, and mint also provided inhibition.  From:  Irkin, R., & Korukluoglu, M. (2009). Growth inhibition of pathogenic bacteria and some yeasts by selected essential oils and survival of L. monocytogenes and C. albicans in apple–carrot juice. Foodborne pathogens and disease, 6(3), 387-394.
• Salad preservation was lengthened with the essential oils of thyme verbena, thyme, oregano, ajowan, tea tree, clove, sage, and rosemary.  From:  Molinos, A. C., Abriouel, H., López, R. L., Omar, N. B., Valdivia, E., & Gálvez, A. (2009). Enhanced bactericidal activity of enterocin AS-48 in combination with essential oils, natural bioactive compounds and chemical preservatives against Listeria monocytogenes in ready-to-eat salad. Food and Chemical Toxicology, 47(9), 2216-2223.

FEMALE HEALTH

• A combination of oral probiotics and a topical tea tree oil treatment reduced vaginal Candida in this small human study.  From:  Di Vito, M., Fracchiolla, G., Mattarelli, P., Modesto, M., Tamburro, A., & Padula, F. (2016). Probiotic and Tea Tree Oil Treatments Improve Therapy of Vaginal Candidiasis: A Preliminary Clinical Study. Med J Obstet Gynecol, 4(4), 1090.
• Tea tree oil was effective against vaginal Candida ssp. In vitro.  From:  Di Vito, M., Mattarelli, P., Modesto, M., Girolamo, A., Ballardini, M., Tamburro, A., … & Mondello, F. (2015). In vitro activity of tea tree oil vaginal suppositories against Candida spp. and probiotic vaginal microbiota. Phytotherapy Research, 29(10), 1628-1633.
• In a double blind study, tea tree may have reduced the recurrent herpes labialis virus (RHL) or cold sores but further research is necessary.  From:  Carson, C. F., Ashton, L., Dry, L., Smith, D. W., & Riley, T. V. (2001). Melaleuca alternifolia (tea tree) oil gel (6%) for the treatment of recurrent herpes labialis. Journal of Antimicrobial Chemotherapy, 48(3), 450-451.
• In a study of 30 different vaginal isolated strains of C. albicans to twelve essential oils, compared to the three of the mainly used drugs (clotrimazole, fluconazole, itraconazole), mint, basil, lavender, tea tree oil, winter savory and oregano essential oils inhibited both the growth and the activity of C. albicans more efficiently than clotrimazole.  From:  Bona, E., Cantamessa, S., Pavan, M., Novello, G., Massa, N., Rocchetti, A., … & Gamalero, E. (2016). Sensitivity of Candida albicans to essential oils: are they an alternative to antifungal agents?. Journal of Applied Microbiology.
• Terpinen-4-ol was active against candida species in the rat vagina.  From:  Mondello, F., De Bernardis, F., Girolamo, A., Cassone, A., & Salvatore, G. (2006). In vivo activity of terpinen-4-ol, the main bioactive component of Melaleuca alternifolia Cheel (tea tree) oil against azole-susceptible and-resistant human pathogenic Candida species. BMC infectious diseases, 6(1), 158.

CHILDREN’S HEALTH

• Tea tree oil was effective against head lice.  From:  Di Campli, E., Di Bartolomeo, S., Pizzi, P. D., Di Giulio, M., Grande, R., Nostro, A., & Cellini, L. (2012). Activity of tea tree oil and nerolidol alone or in combination against Pediculus capitis (head lice) and its eggs. Parasitology research, 111(5), 1985-1992.
• A solution with paw paw, thymol, and tea tree oil was 100% effective in eliminating head lice in participants.  From:  McCage, C. M., Ward, S. M., Paling, C. A., Fisher, D. A., Flynn, P. J., & McLaughlin, J. L. (2002). Development of a paw paw herbal shampoo for the removal of head lice. Phytomedicine, 9(8), 743-748.
• In a child, tea tree oil was effective against hand warts due to the human papilloma virus.  From:  Millar, B. C., & Moore, J. E. (2008). Successful topical treatment of hand warts in a paediatric patient with tea tree oil (Melaleuca alternifolia). Complementary therapies in clinical practice, 14(4), 225-227.
• Tea tree and lavender were effective against a wide range of mites, lemon was effective against some mites, but not lice. From:  Williamson, E. M., Priestley, C. M., & Burgess, I. F. (2007). An investigation and comparison of the bioactivity of selected essential oils on human lice and house dust mites. Fitoterapia, 78(7), 521-525.
• Lavender and tea tree reduced head lice.  From:  Barker, S. C., & Altman, P. M. (2010). A randomised, assessor blind, parallel group comparative efficacy trial of three products for the treatment of head lice in children-melaleuca oil and lavender oil, pyrethrins and piperonyl butoxide, and a. BMC dermatology, 10(1), 6.

ANTI-ALLERGY

• Tea tree and lavender were effective against a wide range of mites, lemon was effective against some mites, but not lice. From:  Williamson, E. M., Priestley, C. M., & Burgess, I. F. (2007). An investigation and comparison of the bioactivity of selected essential oils on human lice and house dust mites. Fitoterapia, 78(7), 521-525.
• Tea tree oil reduced histamine-induced skin inflammation in humans.  From:  Koh, K. J., Pearce, A. L., Marshman, G., Finlay‐Jones, J. J., & Hart, P. H. (2002). Tea tree oil reduces histamine‐induced skin inflammation. British Journal of Dermatology, 147(6), 1212-1217.
• Topical tea tree oil and terpinen-4-ol and α-terpineol affected oedema associated with the efferent phase of a contact hypersensitivity response in mice.  From:  Brand, C., Grimbaldeston, M. A., Gamble, J. R., Drew, J., Finlay-Jones, J. J., & Hart, P. H. (2002). Tea tree oil reduces the swelling associated with the efferent phase of a contact hypersensitivity response. Inflammation Research, 51(5), 236-244.

By: Kathy Sadowski

Updated: 2/18/2020