Tea tree oil

Origin of this essential oil, the tea tree, Melaleuca alternifolia.
Tea tree plantation, Coraki, New South Wales.

Tea tree oil, also known as melaleuca oil or ti tree oil, is an essential oil with a fresh camphoraceous odor and a colour that ranges from pale yellow to nearly colourless and clear. It is taken from the leaves of the Melaleuca alternifolia, which is native to Southeast Queensland and the Northeast coast of New South Wales, Australia.

Tea tree oil is toxic when taken by mouth,[1][2] but is widely used in low concentrations in cosmetics and skin washes.[3] Tea tree oil has been claimed to be useful for treating a wide variety of medical conditions. Tea tree oil has been used as a home remedy for skin conditions, including dandruff, acne, lice, herpes, and other infections.[4] However, the quality of the evidence for effectiveness in these conditions is low.[5][1] Tea tree oil is not recommended for oral consumption or for treating fungal infections or any childhood conditions.[6][7][8]

Uses

Tea tree oil has been used in traditional medicine in attempts to treat acne, nail fungus, and athlete's foot, however, little evidence supports these uses.[5][7] Tea tree oil is not recommended for treating nail fungus, as the evidence for its effectiveness is weak, and does not suggest it would outperform conventional treatments.[6]

Tea tree oil is not recommended for treating head lice in children because its safety has not been established and it could cause skin irritation or allergic reactions.[8]

Safety

Tea tree oil is poisonous when taken internally.[1] According to the American Cancer Society, ingesting tea tree oil has been reported to cause drowsiness, confusion, hallucinations, coma, unsteadiness, weakness, vomiting, diarrhea, stomach upset, blood cell abnormalities, and severe rashes. It should be kept away from pets and children.[1] Because of this tea tree oil should not be used in or around the mouth.[2]

A 2006 review of the toxicity of tea tree oil concluded that it may be used externally in its diluted form by the majority of individuals without adverse effect (provided oxidation is avoided).[9] Topical application of tea tree oil can cause adverse reactions at high concentration. Adverse effects can include skin irritation, allergic contact dermatitis, systemic contact dermatitis, linear immunoglobulin A disease, erythema multiforme like reactions, and systemic hypersensitivity reactions.[4][10] Some people experience allergic contact dermatitis as a reaction to dermal contact with tea tree oil. Allergic reactions may be due to the various oxidation products that are formed by exposure of the oil to light and/or air.[10][11] Exposure of tea tree oil to air and light results in oxidation of some of its components. Oxidized tea tree oil should not be used.[12]

Pets

In dogs and cats, death[13][14] or transient signs of toxicity (lasting 2 to 3 days), such as depression, weakness, incoordination and muscle tremors, have been reported after external application at high doses.[15] In rats the median lethal dose (LD50) is 1.9–2.4 ml/kg.[16]

Composition and characteristics

Tea tree oil composition,
as per ISO 4730 (2004)[3]
Component Concentration
terpinen-4-ol 30–48%
γ-terpinene 10–28%
α-terpinene 5–13%
1,8-cineole 0–15%
terpinolene 1.5–5%
α-terpineol 1.5–8%
α-pinene 1–6%
p-cymene 0.5–8%

Tea tree oil is defined by the International Standard ISO 4730 ("Oil of Melaleuca, Terpinen-4-ol type"), which specifies levels of 15 components needed to define an oil as "tea tree oil." The oil has been described as having a fresh, camphor-like smell.[17]

Tea tree oils come in six different chemical combinations: a terpinen-4-ol type, a terpinolene type, and four 1,8-cineole types. These various oil types contain over 98 compounds, with terpinen-4-ol the major component responsible for antimicrobial and anti-inflammatory properties.[18] A second component 1,8-cineole, is likely responsible for most adverse reactions to TTO products. Adverse reactions diminish with minimization of 1,8-cineole content. In commercial production, TTO is prepared as a terpinen-4-ol type.[4]

History and extraction

The name tea tree is used for several plants, mostly from Australia and New Zealand, from the family Myrtaceae, related to the myrtle. The use of the name probably originated from Captain James Cook's description of one of these shrubs that he used to make an infusion, to drink in place of tea.

The commercial tea tree oil industry originated in the 1920s when Arthur Penfold, an Australian, investigated the business potential of a number of native extracted oils; he reported that tea tree oil had promise, as it exhibited powerful antiseptic properties.[19]

Tea tree oil was first extracted from Melaleuca alternifolia in Australia, and this species remains the most important commercially. In the 1970s and 1980s, commercial plantations began to produce large quantities of TTO from Melaleuca alternifolia. Many of these plantations are located in New South Wales.[20] Since the 70's and 80's, the industry has expanded to include several other species for their extracted oil: Melaleuca armillaris and Melaleuca styphelioides in Tunisia and Egypt; Melaleuca leucadendra in Egypt, Malaysia and Vietnam; Melaleuca acuminata in Tunisia; Melaleuca ericifolia in Egypt; and Melaleuca quinquenervia in the United States. Similar oils can also be produced by water distillation from Melaleuca linariifolia and Melaleuca dissitiflora.[21]

Research

A 2008 article from the American Cancer Society says that studies have previously suggested a possible role for the topical application of tea tree oil as an antiseptic, but that, "despite years of use, available clinical evidence does not support the effectiveness of tea tree oil for treating skin problems and infections in humans."[1] Other uses that have been researched include applications for nail fungus, dandruff, acne, and athlete's foot, but the evidence is of poor quality.[5] A 2012 review of head lice treatment recommended against the use of tea tree oil on children because it could cause skin irritation or allergic reactions, because of contraindications, and because of a lack of knowledge about the oil's safety and effectiveness.[8]

See also

References

  1. 1 2 3 4 5 Russell J, Rovere A, eds. (2009). "Tea Tree Oil". American Cancer Society Complete Guide to Complementary and Alternative Cancer Therapies (2nd ed.). American Cancer Society. ISBN 9780944235713.
  2. 1 2 "Tea Tree Oil". National Capital Poison Center. Retrieved 4 December 2013.
  3. 1 2 "Opinion on Tea tree oil" (PDF). SCCP/1155/08 Scientific Committee on Consumer Products. 16 December 2008.
  4. 1 2 3 Pazyar, N; Yaghoobi, R; Bagherani, N; Kazerouni, A (July 2013). "A review of applications of tea tree oil in dermatology". International Journal of Dermatology. 52 (7): 784–90. PMID 22998411. doi:10.1111/j.1365-4632.2012.05654.x.
  5. 1 2 3 "Tea tree oil". National Center for Complementary and Integrative Health (NCCIH). Retrieved 30 May 2016.
  6. 1 2 "Fungal nail infection" (Clinical Knowledge Summary). National Institute for Health and Care Excellence. 2014. Retrieved 16 January 2017.
  7. 1 2 "Fungal skin infection - foot" (Clinical Knowledge Summary). UK National Institute for Health and Care Excellence. 2014. Retrieved 16 January 2017.
  8. 1 2 3 Eisenhower, Christine; Farrington, Elizabeth Anne (2012). "Advancements in the Treatment of Head Lice in Pediatrics". Journal of Pediatric Health Care. 26 (6): 451–61; quiz 462–4. PMID 23099312. doi:10.1016/j.pedhc.2012.05.004.
  9. ↑ Hammer, KA; Carson, CF; Riley, TV; Nielsen, JB (May 2006). "A review of the toxicity of Melaleuca alternifolia (tea tree) oil.". Food and Chemical Toxicology. 44 (5): 616–25. PMID 16243420. doi:10.1016/j.fct.2005.09.001.
  10. 1 2 Hammer, K; Carson, C; Riley, T; Nielsen, J (2006). "A review of the toxicity of Melaleuca alternifolia (tea tree) oil". Food and Chemical Toxicology. 44 (5): 616–25. PMID 16243420. doi:10.1016/j.fct.2005.09.001.
  11. ↑ Aberer, W (January 2008). "Contact allergy and medicinal herbs". Journal der Deutschen Dermatologischen Gesellschaft = Journal of the German Society of Dermatology : JDDG. 6 (1): 15–24. PMID 17919303. doi:10.1111/j.1610-0387.2007.06425.x.
  12. ↑ "The Effectiveness and Safety of Australian Tea Tree Oil". Australian Government - Rural Industries and Development Corporation. Retrieved 26 February 2014.
  13. ↑ "Tea Tree Oil and Dogs, Tea Tree Oil and Cats". Petpoisonhelpline.com. Retrieved December 13, 2012.
  14. ↑ "Tea Tree Oil Toxicity". Veterinarywatch. Retrieved December 13, 2012.
  15. ↑ Villar, D; Knight, MJ; Hansen, SR; Buck, WB (April 1994). "Toxicity of melaleuca oil and related essential oils applied topically on dogs and cats". Veterinary and human toxicology. 36 (2): 139–42. PMID 8197716.
  16. ↑ Carson CF, Hammer KA, Riley TV (January 2006). "Melaleuca alternifolia (Tea Tree) oil: a review of antimicrobial and other medicinal properties". Clin. Microbiol. Rev. 19: 50–62. PMC 1360273 Freely accessible. PMID 16418522. doi:10.1128/CMR.19.1.50-62.2006.
  17. ↑ Billee Sharp (18 September 2013). Lemons and Lavender: The Eco Guide to Better Homekeeping. Cleis Press. pp. 43–. ISBN 978-1-936740-11-6.
  18. ↑ 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): 619–26. PMID 11131302. doi:10.1007/s000110050639.
  19. ↑ 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. PMC 1360273 Freely accessible. PMID 16418522. doi:10.1128/CMR.19.1.50-62.2006.
  20. ↑ 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: 50–62. PMC 1360273 Freely accessible. PMID 16418522. doi:10.1128/cmr.19.1.50-62.2006.
  21. ↑ Sávia Perina Portilho Falci (July 2015). "Antimicrobial activity of Melaleuca sp. oil against clinical isolates of antibiotics resistant Staphylococcus aureus". Acta Cirurgica Brasileira. 30 (7): 401–6. PMID 26108028. doi:10.1590/S0102-865020150060000005.
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