About Herbs, Botanicals & Other Products

Scientific Name
Melaleuca alternifolia
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Common Name

Melaleuca oil from Australia

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Clinical Summary

Tea tree oil, derived from the leaves, should only be used topically. The active components are thought to be terpinen-4-ol, alpha-terpineol, and alpha-pinene. Tea tree oil has demonstrated in vitro antimicrobial (2) (12) and antiproliferative (14) (15) properties. Clinical studies suggest efficacy in treating acne (5), tinea pedis (6) (9), distal subungual onychomycosis (7), histamine-induced skin inflammation (8), dandruff (10) warts (16), and cold sores (11).
Oral consumption of tea tree oil has resulted in serious adverse events including coma (1).
Skin irritation and hypersensitivity reactions were reported following topical administration (3). Also, repeated topical exposure to lavender and tea tree oils resulted in gynecomastia in prepubertal boys (13).

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Purported Uses
  • Acne
  • Burns
  • Cold sores
  • Eczema
  • Fungal infections
  • Inflammation
  • Insect bites and stings
  • Mucositis
  • Skin infections
  • Wound healing
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Constituents
  • Volatile Oils: Terpinen-4-ol, 1-8-cineole, alpha-terpineol, sesquiterpenoid, and terpinolene (1)
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Mechanism of Action

Tea tree oil, especially terpinen-4-ol, appears to have antimicrobial activity against Candida albicans, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. In addition, terpin-4-ol, alpha-terpineol, and alpha-pinene were found to possess antimicrobial effects against Staphylococcus epidermidis and Propionibacterium acnes (2). Terpinen-4-ol has also been shown to suppress inflammatory mediator production by activated human monocytes (8).
In vitro studies have shown that tea tree oil has weak estrogenic and antiandrogenic properties that may alter estrogen and androgen signaling pathways (13).

The skin irritation following use of tea tree oil were shown to be due to auto-oxidation of tea tree oil resulting in bioactive oxidized products and by the formation of epoxide intermediates resulting from catalysed arene-epoxidation reactions by selected human cytochrome P450 enzymes (17).

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Warnings

Tea tree oil should only be used topically. Internal administration may cause severe toxicity. Both coma and neutrophil leukocytosis have occurred following oral administration.

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Adverse Reactions

Reported (topical): Local skin irritation and allergic contact dermatitis. (3)
Reported (oral): Disorientation, systemic contact dermatitis, coma, body rash, and neutrophil leukocytosis. (4)
Reported (topical): Repeated application of lavender and tea tree oils resulted in gynecomastia in prepubertal boys. (13)

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Herb-Drug Interactions

None known

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References
  1. Osborne F, et al. Australian tea tree oil. Herbal Medicine 1998 March;42-6.
  2. May J, et al. Time-kill studies of tea tree oils on clinical isolates. J Antimicrob Chemother 2000;45:639-43.
  3. Rubel DM, Freeman S, Southwell IA. Tea tree oil allergy: what is the offending agent? Report of three cases of tea tree oil allergy and review of the literature. Australia J Dermatol 1998;39:244-7.
  4. Carson C, Riley TV, Cookson BD. Efficacy and safety of tea tree oil as a topical antimicrobial agent. J Hosp Infect 1998;40:175-8.
  5. Bassett IB, Pannowitz DL, Barnetson RS. A comparative study of tea tree oil versus benzol peroxide in the treatment of acne. Med J Aust 1990;153:455-8.
  6. Tong MM, Altman PM, Barnetson RS. Tea tree oil in the treatment of tinea pedis. Australia J Dermatol 1992;33:145-9.
  7. 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;38:601-5.
  8. Koh KJ, et al. Tea tree oil reduces histamine-induced skin inflammation. Br J Dermatol 2002;147:1212-7.
  9. Satchell AC, et al. Treatment of interdigital inea pedis with 25% and 50% tea tree oil solution: A randomized, placebo-controlled, blinded study. Australas J Dermatol 2002; 43: 175-8.
  10. Satchell AC, et al. Treatment of dandruff with 5% tea tree oil shampoo. J Am Acad Dermatol 2002; 47(6): 852-5.
  11. Carson CF, et al. Melaleuca alternifolia (tea tree) oil gel (6%) for the treatment of recurrent herpes labialis. J Antimicrob Chemother 2001; 48: 450-1.
  12. Bagg J, 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.
  13. Henley DV, Lipson N, Korach KS, et al. Prepubertal gynecomastia linked to lavender and tea tree oils. N Engl J Med 2007;356(5):479-85.
  14. 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 Feb;122(2):349-60.
  15. Greay SJ, Ireland DJ, Kissick HT, et al. Induction of necrosis and cell cycle arrest in murine cancer cell lines by Melaleuca alternifolia (tea tree) oil and terpinen-4-ol. Cancer Chemother Pharmacol. 2009 Aug 13. [Epub ahead of print]
  16. Millar BC, Moore JE. Successful topical treatment of hand warts in a paediatric patient with tea tree oil (Melaleuca alternifolia). Complement Ther Clin Pract. 2008 Nov;14(4):225-7.
  17. Meesters RJ, Duisken M, Hollender J. Cytochrome P450-catalysed arene-epoxidation of the bioactive tea tree oil ingredient p-cymene: indication for the formation of a reactive allergenic intermediate? Xenobiotica. 2009 Sep;39(9):663-71.
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How It Works

Bottom Line: Tea tree oil may be effective in treating certain skin conditions. More studies are needed.

Tea tree oil is the essential oil distilled from Melaleuca alternifolia, a plant native to Australia. In laboratory tests, tea tree oil effectively killed a number of the bacteria and fungi most commonly found in skin infections and acne, including Candida albicans, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus epidermidis and Propionibacterium acnes. Tea tree oil was also found effective against some cancer cells in the laboratory.
In healthy volunteers, a tea tree oil extract was able to reduce inflammation caused by histamine injections.

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Purported Uses
  • To treat acne
    One clinical trial showed that tea tree oil was as effective as benzoyl peroxide in treating acne, but there is no other evidence to support this use.
  • To treat minor burns
    No scientific evidence supports this use.
  • To treat fungal infections of the skin, fingernails, toenails
    One clinical trial showed that tea tree oil was as effective as antifungal medicines against fingernail/toenail fungal infections. However, clinical trials have presented mixed results when used to treat fungal infections of the foot.
  • To reduce inflammation
    One study shows that tea tree oil reduces inflammation caused by histamine injections in healthy volunteers, but there is no proof from clinical trials that it can reduce swelling from other causes (bee stings, psoriasis, eczema).
  • To treat insect bites and stings
    Tea tree oil may be able to reduce inflammation, but otherwise no scientific evidence supports this use.
  • To treat mucositis (swelling of the mucous membranes of the mouth)
    No scientific evidence supports this use. Intake of tea tree oil by mouth can cause severe toxicity.
  • To promote the healing of wounds
    Although they may have antimicrobial properties, tea tree oil products are not guaranteed sterile and therefore should not be applied to open wounds.
  • To treat dandruff
    One clinical trial supports this use.
  • To treat cold sores
    One small study shows possible benefits, but further study is necessary. Intake of tea tree oil by mouth can cause severe toxicity.
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Patient Warnings
  • Tea tree oil should only be used topically. When taken by mouth, it can cause severe toxicity, including an abnormal elevation in white blood cell count and coma.
  • This product is regulated by the FDA as a dietary supplement. Unlike approved drugs, supplements are not required to be manufactured under specific standardized conditions. This product may not contain the labeled amount or may be contaminated. In addition, it may not have been tested for safety or effectiveness.
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Side Effects
  • When used topically, local skin irritation and/or an allergic reaction (contact dermatitis: itching, redness, and swelling) can occur.
  • When taken by mouth, tea tree oil can cause disorientation, whole body rash, and an abnormal elevation in white blood cell count.
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Dosage (Inside MSKCC Only)
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Aliases
Melaleuca Alternifolia
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Last updated: June 30, 2011