Tea tree is a small tree native to the northeast coast of New South Wales, Australia. The name “tea tree” comes from its use by early Australians as a beverage tea. The leaves were used by indigenous peoples of Australia for the treatment of fever, wounds, and as a refreshing tea. The first written medical testimony of tea tree was published in the Medical Journal of Australia in 1930 discussing the use of tea tree oil as a wound disinfectant. The oil was issued to soldiers during WWII as an antiseptic.
The oil is obtained by steam distillation of the leaves, which yield a colorless, or pale yellow oil containing 50-60% terpenes. In vitro data has shown that tea tree oil has impressive antifungal activity.1 Constituents within tea-tree essential oil, terpinen-4-ol, alpha-terpineol and alpha-pinene have been shown to be active against Staphylococcus aureus, S. epidermidis and Propionibacterium acnes in vitro.2 Research has shown that tea tree oil has germicidal activity against both Candida albicans and Trichomonas vaginalis. 3
Clinical Applications: Nail Fungus (Onychomycosis)
While the data is not conclusive, there is intriguing evidence to suggest that tea tree oil is an effective treatment for onychomycosis. Given the high cost and potentially severe adverse effects that can occur with administration of oral antifungal agents, this herbal essential oil is deserving of more attention. A double-blind, multi-center, randomized controlled trial of 117 patients with distal subungual onychomycosis proven by culture was conducted to compare the efficacy of clotrimazole vs tea tree oil. Patients received twice-daily application of either 1% clotrimazole (CL) solution or 100% tea tree (TT) oil for 6 months. Debridement and clinical assessment were performed at 0, 1, 3, and 6 months. Cultures were obtained at 0 and 6 months. After 6 months of therapy, the two treatment groups were comparable based on culture cure (CL = 11%, TT = 18%) and clinical assessment documenting partial or full resolution (CL = 61%, TT = 60%). Three months later, about one half of each group reported continued improvement or resolution (CL = 55%; TT = 56%).4 Of course, combining tea tree oil with other antifungal agents might increase its effectiveness. A randomized, double-blind, placebo-controlled study was conducted in 60 outpatients (18-80 years old) with onychomycosis for 6-36 months duration to examine the clinical efficacy and tolerability of 2% butenafine hydrochloride and 5% Melaleuca alternifolia oil incorporated in a cream to manage toenail onychomycosis in a cohort. After 16 weeks, 80% of patients using medicated cream were cured, as opposed to none in the placebo group. Four patients in the active treatment group experienced subjective mild inflammation without discontinuing treatment.5
There are a number of essential oils that have activity against the bacteria associated with acne. A single-blind, randomized clinical trial on 124 patients was conducted to evaluate the efficacy and skin tolerance of 5% tea-tree oil gel in the treatment of mild to moderate acne when compared with 5% benzoyl peroxide lotion. The results demonstrated that both 5% tea-tree oil and 5% benzoyl peroxide had a significant effect in ameliorating the patients' acne by reducing the number of inflamed and non-inflamed lesions (open and closed comedones), although the onset of action in the case of tea-tree oil was slower. However, patients treated with tea-tree oil experienced fewer side effects.6 Those who find the benzoyl peroxide too drying and irritating might consider using tea tree oil instead.
Bacterial Vaginosis/Vaginal Candidiasis
In vitro studies indicate that a number of organisms associated with bacterial vaginosis are susceptible to tea tree oil and, interestingly, friendly lactobacilli are relatively resistant to the herb.7 This in vitro data supports a case study that reported a patient's successful self-treatment with tea tree oil in eliminating anaerobic bacterial vaginosis. After an office visit documenting anaerobic bacterial vaginosis, the patient refused treatment with metronidazole and instead used a five-day course of vaginal pessaries containing 200 milligrams of tea tree. After treatment, the patient was symptom free and the vaginal flora comprised primarily of gram-positive bacilli.8
There is significant in vitro evidence for the antifungal activity of the essential oil against a large number of Candida spp.9 The clinical trials have been small but are consistent with data generated from in vitro and animal research. An open trial of 28 patients with VVC inserted a tea tree oil suppository into the vagina before bedtime. After 30 days, 21/28 patients showed complete recovery, while the remaining 7 patients were clinically asymptomatic.10 Another small trial showed improvement in eight of twelve AIDS patients with oral candidiasis refractory to fluconazole after 4 weeks of treatment with an oral solution of Melaleuca alternifolia.11 Some practitioners recommend saturating a tampon in a 40% solution of tea tree oil and leaving it in the vagina for 24 hours for the treatment of vaginal fungal and bacterial infections, as tea tree oil has been shown to effective in destroying Trichomonas vaginalis. A 40% solution is made water miscible by the addition of 13% isopropyl alcohol.12 Tea tree oil pessaries are, however, easier to use and can be purchased at many health food stores.
Tea tree essential oil has well documented antiseptic activity and is commonly use as a topical agent to prevent and treat minor bacterial infections. Interest has been generated in the potential role for plant essential oils for the treatment of antibiotic resistant infections. A recent paper by Anderson and Fennessy concluded that there was compelling in vitro evidence of the effectiveness of tea tree oil against methicillin-resistant Staphylococcus aureus (MRSA),13 while a case report demonstrated the efficacy of a mixture of essential oils (including tea tree) administered percutaneously, via calcium sulfate pellets in a human case of chronic MRSA osteomyelitis.14 While this data is preliminary – it is an intriguing glimpse into the potential usefulness of botanicals for the growing worldwide problem of antibiotic resistance.
There are a number of case reports in the medical literature of dermatitis occurring after the topical application of tea tree oil.15 More than 30 cases have been documented in the literature since 1991. Tea tree oil kept in open and closed bottles undergoes photooxidation within a few days to several months, leading to the creation of degradation products that are moderate to strong sensitizers. Peroxides, epoxides and endoperoxides, like ascaridol and 1,2,4-trihydroxy menthane, are formed. These are likely responsible for the development of allergic contact dermatitis seen in individuals treating themselves with the oil.16 Other than allergic contact dermatitis, there have been no adverse events reported when tea tree oil is used topically. There are no reports of significant systemic absorption with the appropriate topical application of tea tree oil.
Anecdotal and case reports in adults and children have demonstrated toxicity with as little as 10 mL of ingested essential oil.17 Internal use of essential oil is not advised (other than oral rinse that is not swallowed or as a vaginal douche).
There are no reports of herb-drug interaction with topical use.
2 Raman A, Weir U, Bloomfield SF. Antimicrobial effects of tea-tree oil and its major components on Staphylococcus aureus, Staph. epidermidis and Propionibacterium acnes. Lett Appl Microbiol 1995 Oct; 21(4): 242-5.
4 Buck DS, Nidorf DM, Addino JG. Comparison of two topical preparations for the treatment of onychomycosis: Melaleuca alternifolia (tea tree) oil and clotrimazole. J Fam Pract 1994 Jun; 38(6): 601-5.
5 Syed TA, Qureshi ZA, Ali SM, Ahmad S, Ahmad SA. Treatment of toenail onychomycosis with 2% butenafine and 5% Melaleuca alternifolia (tea tree) oil in cream. Trop Med Int Health. 1999 Sep; 4(9): 630.
6 Bassett IB, Pannowitz DL, Barnetson RS. A comparative study of tea-tree oil versus benzoylperoxide in the treatment of acne. Med J Aust 1990 Oct 15; 153(8):455-8
7 Hammer KA, Carson CF, Riley TV. In-vitro activity of essential oils, in particular Melaleuca alternifolia (tea tree) oil and tea tree oil products, against Candida spp. J Antimicrob Chemother 1998 Nov; 42(5): 591-5
8 Blackwell AL. Tea tree oil and anaerobic (bacterial) vaginosis. Lancet 1991; 337: 300.
9 Hammer KA, Carson CF, Riley TV. In-vitro activity of essential oils, in particular Melaleuca alternifolia (tea tree) oil and tea tree oil products, against Candida spp. J Antimicrob Chemother 1998; 42(5): 591-5.
10 Belaiche P. Treatment of vaginal infections of Candida albicans with the essential oil of Melaleuca alternifolia. In: Botanical Influences on Illness: A Sourcebook of Clinical Research. Werbach WR and Murray MT (Eds). Third Line Press, Tarzana, CA, 2000; 201.
11 Jandourek A, Vaishampayan JK, Vasquez JA. Efficacy of melaleuca oral solution for the treatment of fluconazole refractory oral candidiasis in AIDS patients. AIDS 1998; 12(9): 1033-37.
12 Bottoni D. Tea tree oil. International Journal of Pharmaceutical Compounding 1998; 2(4): 284-5.
13 Anderson JN, Fennessy PA: Can tea tree (Melaleuca alternifolia) oil prevent MRSA? Medical Journal of Australia 2000 173: 489
14 Sherry E, Boeck H, Warnke PH. Percutaneous treatment of chronic MRSA osteomyelitis with a novel plant-derived antiseptic. BMC Surg 2001; 1(1): 1
15 Fritz TM, Burg G, Krasovec M. Allergic contact dermatitis to cosmetics containing Melaleuca alternifolia (tea tree oil) Ann Dermatol Venereol 2001 Feb; 128(2): 123-6
16 Hausen BM, Reichling J, Harkenthal M. Degradation products of monoterpenes are the sensitizing agents in tea tree oil. Am J Contact Dermat 1999; 10(2): 68-77
17 Del Beccaro MA. Melaleuca oil poisoning in a 17 month old. Vet Human Toxicol 1995; 37: 557-58.