Tea Tree Oil
Scientific Name(s): Melaleuca alternifolia Cheel. Family: Myrtaceae
Common Name(s): Tea tree oil
Clinical Overview
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Uses of Tea Tree Oil
Tea tree oil has been used mainly for its antimicrobial effects. TTO should only be applied topically. Do not ingest orally.
Tea Tree Oil Dosing
TTO has been studied for its topical antifungal activity incorporated in cream formulations of 5% and 10% and as the neat oil. Standardized tea tree oil contains less than 10% cineole and greater than 30 percent terpinen-4-ol. Dosage should initially start low to avoid irritation caused by cineole. CNS toxicity has been observed with internal doses of 10 to 70 mL. 1 , 2 , 3
Contraindications
Oral ingestion is contraindicated.
Pregnancy/Lactation
Information regarding safety and efficacy in pregnancy and lactation is lacking. Avoid use.
Tea Tree Oil Interactions
None well documented.
Tea Tree Oil Adverse Reactions
Use of tea tree oil has resulted in allergic contact eczema and dermatitis.
Toxicology
Apart from the side effects information, various additional reports on TTO toxicity can be referenced. 4 , 5 , 6
Botany
There are many plants known as “tea trees,” but the species Melaleuca alternifolia is responsible for the “tea tree oil,” which has recently gained popularity. Native to Australia, the tea tree is found in coastal areas. It is an evergreen shrub that can grow to 6 meters tall. Its narrow, 4 cm, “needle-like” leaves release a distinctive aroma when crushed. The fruits grow in clusters, and its white flowers bloom in the summer. 7
Other related species include M. quinquenervia (Cav.) S.T. Blake ( M. viridiflora sol.) from the Caledonian evergreen tree yielding “niaouli oil” and M. leucaden L. and M. cajuputi Powell (= M. minor sm.) yielding “oil of cajuput.” These oils contain similar constituents resembling camphor and peppermint and are used in aromatherapy. 8 , 9
History
Tea tree oil (TTO) was first used in surgery and dentistry in the mid-1920s. Its healing properties were also used during World War II for skin injuries to those working in munition factories. Tea tree oil's popularity has resurfaced within the last few years with help from promotional campaigns and may be present in soaps, shampoos, and lotions. 7
Chemistry
The essential oil is normally obtained by steam distillation of the leaves. 8 The main constituent in tea tree's essential oil is terpin-4-ol, present in concentrations of 40% or more. 7 , 8 The related species contain eucalyptol, cineole, nerolidol, viridiflorol, or phenylpropanoids. 8 , 9 Listings of chemical compositions of tea tree oils have been reported. 10 , 11 An overview of essential oil use and purity issues are also available on this topic. 12
Tea Tree Oil Uses and Pharmacology
AntimicrobialTea tree oil has been used mainly for its antimicrobial effects without irritating sensitive tissues. It has been applied to cuts, stings, acne, and burns. In hospitals, TTO has been used in soap form and soaked in blankets to make an antibacterial covering for burn victims. When run through air-conditioning ducts, TTO has been shown to exert bactericidal effects. 7 A considerable amount of literature has become available on this topic.
Disc diffusion and broth microdilution methods have been used to determine antimicrobial effects against eight TTO constituents. Terpin-4-ol was active against Candida albicans , Escherichia coli , Staphylococcus aureus and Pseudomonas aeruginosa . Other constituents of the oil (such as linalool and alpha-terpineol) had some antimicrobial activity as well. 13 , 14 In addition, constituents terpin-4-ol, alpha-terpineol, and alpha-pinene were found to possess antimicrobial effects against Staphylococcus epidermidis and Propionibacterium acnes . 15
Animal dataResearch reveals no animal data regarding the use of tea tree oil as an antimicrobial.
Clinical dataTTO may be useful in removing “transient skin flora while suppressing but maintaining resident flora.” 16 TTO was also shown to be an effective topical treatment of monilial and fungal dermatoses and superficial skin infections in 50 human subjects over a 6–month period with minimal or no side effects reported. 17 A report suggests TTO to be useful in treatment of “methicillin-resistant S. aureus (MRSA) carriage.” In this evaluation, all 66 isolates of S. aureus were susceptible to the essential oil (64 isolates being MRSA, 33 being mupirocin-resistant). 18
TTO's activity against anaerobic oral bacteria has been surveyed. 19 A case report exists, discussing antibacterial efficacy of TTO in a 40-year-old woman with anaerobic vaginosis. 20
In a randomized, double-blind study comparing the efficacy of 10% (w/w) tea tree oil cream with 1% tolnaftate (and placebo creams) against tinea pedis (athlete's foot), TTO was found to be as effective as tolnaftate in reducing symptoms but no more effective than placebo in achieving mycological cure. 1 In a report on onychomycosis (nail fungus), TTO (100%) vs clotrimazole solution (1%) application yielded similar results in treatment. Both therapies, however, had high recurrence rates. 2
Other usesTTO can be added to baths or vaporizers to help treat respiratory disorders. Related species oil has been used for nasal antiseptic purposes, pulmonary anti-inflammatory use, and for coughs. 7 , 8 , 9 TTO is also used in perfumery and aromatherapy. 8
Dosage
TTO has been studied for its topical antifungal activity incorporated in cream formulations of 5% and 10% and as the neat oil. Standardized tea tree oil contains less than 10% cineole and greater than 30% terpinen-4-ol. Dosage should initially start low to avoid irritation caused by cineole. CNS toxicity has been observed with internal doses of 10 to 70 mL. 1 , 2 , 3
Pregnancy/Lactation
Information regarding safety and efficacy in pregnancy and lactation is lacking. Avoid use.
Interactions
None well documented.
Adverse Reactions
Allergic contact eczema was found to be caused primarily by the α-limonene constituent (in TTO) in 7 patients tested. In this same report, alpha-terpinene and aromadendrene additionally caused dermatitis in 5 of the patients. 21 Eucalyptol was found to be the contact allergen in a Dutch report. 22 Contact allergy due to TTO may be related to cross-sensitization to colophony. 23 A case report describes a petechial body rash and marked neutrophil leukocytosis in a 60-year-old man who ingested one half teaspoonful of the oil (for common cold symptoms). He recovered 1 week later. 24
TTO in comparison to conifer resin acids was found to exhibit no cytotoxic activity in vitro using human epithelial and fibroblast cells. 25
Another case report describes ataxia and drowsiness as a result of oral TTO ingestion (less than 10 mL) by a 17-month-old male. He was treated with activated charcoal, which was only partially successful, but after a short time appeared normal and was discharged 7 hours after ingestion. 26
Toxicology
Various additional reports on TTO toxicity can be referenced. 4 , 5 , 6
Bibliography
1. Tong MM, Altman PM, Barnetson RS. Tea tree oil in the treatment of tinea pedis. Australas J Dermatol . 1992;33:145-149.2. 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;38:601-605.
3. Syed TA, Qureshi ZA, Ali SM, Ahmad S, Ahmad SA. Treatment of toenail onchomycosis with 2% butenafine and 5% Melaleuca alternifolia (tea tree) oil in cream. Trop Med Int Health . 1999;4:284-287.
4. de Groot A, et al. Contact Dermatitis 1993;28(5):309.
5. Moss A. Med J Aust 1994;160(4):236.
6. Carson, et al. J Toxicol Clin Toxicol 1995;33(2):193-94.
7. Low T, et al. (contributing editors). Reader's Digest (Aust) Magic and Medicines of Plants. Surry Hills, NSW, 2010 Australia: PTY Limited 1994;349.
8. Bruneton J. Medicinal Plants . Seaucus, NY: Lavoisier Publ. Inc. 1995;461.
9. Osol, et al, eds. The Dispensatory of the United States of America. Philadelphia, PA: J.B. Lippincott Co. 1960;1750.
10. Altman, P. Aust J Pharm 1988 Apr;69:276-78.
11. Lawrence B. Perfumer and Flavorist 1990 May-Jun;15:63-69.
12. “Anon.” Manufacturing Chemist 1993 Mar;64:20–21,23.
13. Carson C, et al. J Appl Bacteriol 1995;78(3):264–69.
14. Carson C, et al. Microbios 1995;82(332):181–85.
15. Raman A, et al. Letters in Applied Microbiology 1995;21(4):242–45.
16. Hammer K, et al. Am J Infect Control 1996;24(3):186-89.
17. Shemesh A, et al. Aust J Pharm 1991 Sep;72:802-3.
18. Carson C, et al. J Antimicrob Chemother 1995;35(3):421-24.
19. Shapiro S, et al. Oral Microbiology and Immunology 1994;9(4):202-8.
20. Blackwell A. Lancet 1991;337(Feb 2):300.
21. Knight T, et al. J Am Acad Dermatol 1994;30(3):423-27.
22. Van der Valk P, et al. Ned Tijdschr Geneeskd 1994;138(16):823-25.
23. Selvaag E, et al. Contact Dermatitis 1994;31(2):124–25.
24. Elliott C. Med J Aust 1993 Dec 6;159:830-31.
25. Soderberg T, et al. Toxicology 1996;107(2):99-109.
26. Del Beccaro M. Vet Hum Toxicol 1995;37(6):557–58.
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Compare Tea Tree Oil with other medications for the treatment of:
Skin Infection, Skin and Structure Infection, Burns, External, Bacterial Skin Infection, Acne
