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Tea Tree Oil

Medically reviewed by Drugs.com. Last updated on Jun 16, 2017.

Scientific Name(s): Melaleuca alternifolia Cheel.
Common Name(s): Melaleuca oil, Tea tree oil

Clinical Overview

Use

Despite an abundance of commercial preparations promoted for antimicrobial use, sound clinical trials are limited. Studies have been conducted in conditions including nail infections, athlete's foot, fungal skin infections, acne, methicillin-resistant Staphylococcus aureus (MRSA) colonization, and hemorrhoids. Case reports exist for use in other conditions.

Dosing

Decolonization of MRSA: Tea tree oil as a nasal cream (4% to 10%) applied 3 times a day for 5 days and 5% body wash for 5 days. Prevention of MRSA colonization: Body wash containing 5% tea tree oil daily. Acne vulgaris: 5% tea tree oil gel applied for 20 minutes twice daily, then washed off. Onchomycosis (fungal nail infections): 100% tea tree oil applied for 6 months. Tinea pedis (athlete's foot): 25% to 50% tea tree oil for 4 weeks.

Contraindications

Oral ingestion is contraindicated.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

Case reports exist of dermatitis associated with topical tea tree oil.

Toxicology

Tea tree oil is toxic when ingested orally. Some case studies of accidental and intentional poisoning exist; however, no deaths have been reported to the American Association of Poison Control Centers through 2012. Mutagenicity of tea tree oil appears to be low; however, chemical constituents have been shown to be cytotoxic and embryotoxic.

Scientific Family

  • Myrtaceae

Botany

There are many plants known as tea trees, but the species M. alternifolia is the source of tea tree essential oil. Native to Australia coastal areas, the tea tree is an evergreen shrub that grows from 5 to 8 m in height. 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. Ornamental Leptospermum species are distinct and are not the source of tea tree oil. Related species include Melaleuca quinquenervia (Cav.) S.T. Blake (Melaleuca viridiflora sol.), a New Caledonian evergreen tree that yields niaouli oil, Melaleuca leucaden L., and Melaleuca cajuputi Powell (synonym, Melaleuca minor Sm.), which is the source of oil of cajuput that contains similar chemical constituents.1, 2

History

The indigenous people of Australia have used tea tree oil from crushed leaves as a traditional remedy for coughs and colds, as well as to treat wounds and skin conditions. Tea tree oil was first used in surgery and dentistry in the mid-1920s. Its healing properties were also used during World War II for skin injuries in munitions factory workers. Tea tree oil's popularity has increased in recent years as interest in natural therapies evolves, and it can be found in soaps, shampoos, and lotions.2, 3

Chemistry

The essential oil is normally obtained by steam distillation of the leaves and terminal branchlets, resulting in a transparent, colorless to pale yellow oil with a characteristic odor. The main constituent in tea tree's essential oil and present in concentrations of 30% or more is terpinen-4-ol, with more than 100 other constituents identified. The International Standards Organization requires 15 of these chemicals to be present, and concentrations of terpinen-4-ol must be at least 30% and 1,8-cineole (controversially considered a skin irritant) must be less than 15%. However, essential oils from other related species (Melaleuca dissitiflora and Melaleuca linariifolia) can also meet these same standards and have been used as adulterants. Other constituents include terpene endoperoxide (ascaridole), terpinene, terpinolene, pinene, cymene, and limonene. The composition of the essential oil may change with storage conditions, because heat, light, air, and moisture can affect the oil.2, 3, 4

Uses and Pharmacology

Acne/Antibacterial

In vitro studies have confirmed bactericidal and bacteriostatic (at lower concentrations) action of tea tree oil. A broad spectrum of bacterial pathogens are affected, including common skin Staphylococcus species, Enterococcus faecalis, and Pseudomonas aeruginosa, and most are susceptible to concentrations of 1% or less of tea tree essential oil; however, the minimum inhibitory concentration (MIC) of some pathogens is as high as 8%. The activity has been attributed mainly to terpineol content, but some studies suggest that cineole has a role.2, 5, 6, 7 The leaf extract of the related species M. quinquenervia is considered weakly active against Helicobacter pylori with a MIC of 100 mcg/mL.40

Animal data

A limited number of dermatological studies have been conducted in animals, particularly for chronic itching and fleas in dogs, but toxicity associated with ingesting the oil via licking limits therapeutic applications.2, 3, 8, 9

Clinical data

Despite the large number of in vitro studies reported, few quality clinical trials have been conducted. Clinical studies have been conducted in acne, methicillin-resistant S. aureus, and gingivitis. Case reports exist for use in bacterial vaginitis.10

One small trial established 5% tea tree oil to be more effective than placebo over 45 days in treating mild to moderate acne vulgaris.11 A second trial demonstrated equivalence with benzoyl peroxide 5% over 3 months of treatment; however, it may have been insufficiently powered to detect a difference.12 A Cochrane review of complementary therapies for acne identified 1 randomized trial (n=60) of low quality that showed a statistically significant benefit of tea tree oil gel for reducing the numbers of skin lesions in acne vulgaris compared to placebo (P<0.00001). Tea tree gel was applied for 20 minutes/day for a duration of 45 days. Adverse effects were minimal and similar between groups.42

In studies evaluating tea tree oil in the decolonization of MRSA nasal application of ointment (4% to 10%) and body wash (5%), no difference was shown versus mupirocin 2% and chlorhexidine or triclosan.13, 14 In subgroup analysis of data from the larger trial, mupirocin nasal ointment performed better than 10% tea tree oil in nasal decolonization, while tea tree oil performed better than chlorhexidine in decolonizing the skin and skin lesions.14 The results of a multicenter, open-label, randomized clinical trial on the effect of 5% tea tree oil wash in preventing methicillin-resistant S. aureus colonization in patients in the intensive care unit (ICU) was undertaken by a group of investigators in Northern Ireland.15 In this study (n = 391 evaluable), 5% tea tree oil body wash or control was used at least daily for bed baths until ICU discharge, or detection of MRSA colonization. There was no significant difference between treatment groups for incidence of MRSA colonization, and no patient in either group developed MRSA bacteremia.35

In 2 small trials, 0.34% tea tree oil mouthwash and 2.5% tea tree oil gel reduced gingival inflammation but did not decrease plaque scores versus chlorhexidine or placebo.16, 17

The American Academy of Dermatology/American Academy of Dermatology Association guidelines of care for the management of acne vulgaris (2016) states that topical tea tree oil is effective for the treatment of acne (limited; moderate).41

Antifungal

A wide range of yeasts, dermatophytes, and other filamentous fungi were susceptible to varying concentrations of tea tree oil. Reported MICs range from 0.12% to 2%, but some species (eg, Aspergillus niger ) require higher concentrations of up to 8%. It has been suggested that different phases of fungal growth are affected differently by tea tree oil.2, 3, 10, 18, 19

Clinical data

Despite an abundance of commercial preparations promoted for antifungal use, clinical trials of sound methodology are limited. Trials have been conducted in conditions including nail infections (onchomycosis), athlete's foot (tinea pedis), ringworm (tinea versicolor), dandruff, oral candidiasis, and case reports of other fungal conditions.

Equivalence was found for 100% tea tree oil and clotrimazole 1% in treating onchomycosis over 6 months in one study.20 However, a study evaluating butenafine with tea tree oil versus tea tree oil alone in treating fungal toenail infections found no effect for tea tree oil alone (the placebo arm of the study) applied over 8 weeks.21

Tea tree oil (25% and 50%) was better than placebo in treating tinea pedis in one clinical trial.22 A second trial found 10% tea tree oil to be no better than placebo in attaining a negative culture, but equivalent to tolnaftate 1% as assessed by reduction of symptoms.23 The popularity of tea tree oil in treating tinea pedis is attributed to the reduction of scaling, itching, and burning symptoms.8

A 5% tea tree oil shampoo used for 4 weeks was shown to be effective in treating dandruff, 24 and in an open-label study with no control arm, tea tree oil resolved oral candidial lesions in some, but not all, patients who were positive for HIV.25

Anti-inflammatory action

Anti-inflammatory action has been described for tea tree oil and may account for observed clinical response of reduced itching. In histamine studies and nickel-induced contact hypersensitivity tests, tea tree oil reduced flare and erythema at higher concentrations (20% to 100%).2, 8, 28, 29, 37

Antiviral

Early studies examined the antiviral action of tea tree oil on tobacco mosaic virus, while in vitro studies in human viruses have been limited mainly to the herpes simplex viruses.2, 3 At 2.5 mcg/mL, tea tree oil suppressed herpes simplex virus type 1 in an in vitro study examining various oils.26 A small pilot study found some benefit in using a 6% tea tree oil gel in the treatment of recurrent herpes labialis over placebo; however, statistical significance was not achieved.27

Hemorrhoidal symptoms

Proctoial topical gel, a proprietary product containing hyaluronic acid with tea tree oil and methylsulfonylmethane, was evaluated in adult patients (n = 36) with grade 1 to 3 hemorrhoids in a randomized, double-blind trial. Patients were instructed to apply the study gel twice daily for 14 days. The active treatment was significantly better than placebo for symptoms including pain, pain during defecation, bleeding, pruritus, and inflammation.36

Other uses

In limited experiments, tea tree oil induced apoptosis and cell cycle arrest in tumor cell lines.9, 30

Tea tree oil was not effective in improving symptoms of dementia or dental irrigation in root canal treatment.31, 32

Dosing

Decolonization of methicillin-resistant Staphylococcus aureus

Tea tree oil as a nasal cream (4% to 10%) applied 3 times a day for 5 days, and 5% body wash for 5 days.13, 14, 15

Methicillin-resistant Staphylococcus aureus colonization prevention

Tea tree oil 5% body wash was used at least daily in 1 study that found no significant reduction in the rate of MRSA colonization.35

Acne vulgaris

5% tea tree oil gel applied for 20 minutes twice daily, then washed off.11, 12

Onchomycosis (fungal nail infections)

100% tea tree oil applied for 6 months.20

Tinea pedis (athlete's foot)

25% to 50% tea tree oil for 4 weeks.22, 23

Pregnancy / Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking. Alpha-terpinene, present in tea tree oil, was embryotoxic in rats.9

Interactions

None well documented.

Adverse Reactions

Case reports describe the irritant effect of topical tea tree oil in contact dermatitis.3, 9, 33 However, the irritant effect of tea tree oil, often attributed to the cineole constituent, has been disputed because 1,8-cineole concentrations of up to 28% have not produced reactions.2, 9 A study of tea tree oil in contact dermatitis reduced the concentration of tea tree oil from 50% to 20% because of skin irritation with the higher concentration.37 A relatively low concentration (ie, 1%) of ascaridole, a terpene endoperoxide that can develop in tea tree oil, has been shown to be a potential sensitizer based on data from 2 case studies.39

Toxicology

Tea tree oil is toxic when ingested orally. The median lethal dose in rats has been estimated to be 1.9 to 2.6 mL/kg.2, 9

Some case studies of accidental and intentional poisoning exist; however, no deaths were reported to the American Association of Poison Control Centers through 2012.2, 9, 38

Internal doses of 10 to 70 mL have resulted in ataxia and decreasing levels of consciousness. Activated charcoal and sorbitol have been used as an antidote in cases of poisoning in children. No ongoing neurological sequelae have been reported.9

Reports of cytotoxicity experienced with tea tree oil vary, and mutagenicity is likewise unclear but appears to be low based on experimental data.9, 26 Ototoxicity has been evaluated in guinea pigs, and strengths of 2% or less are considered safe for use.9

Index Terms

  • Melaleuca cajuputi Powell
  • Melaleuca leucaden L.
  • Melaleuca minor Sm.
  • Melaleuca quinquenervia (Cav.) S.T. Blake
  • Melaleuca viridiflora sol.

References

1. Melaleuca alternifolia Cheel. USDA, NRCS. 2010. The PLANTS Database (http://plants.usda.gov, January 2010). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
2. Carson CF, Hammer KA, Riley TV. Melaleuca alternifolia (tea tree) oil: a review of antimicrobial and other medicinal properties. Clin Microbiol Rev. 2006;19(1):50-62.16418522
3. Crawford GH, Sciacca JR, James WD. Tea tree oil: cutaneous effects of the extracted oil of Melaleuca alternifolia. Dermatitis. 2004;15(2):59-66.15473330
4. International Organization for Standardization. Oil of Melaleuca, terpinen-4-ol type (Tea Tree oil). ISO 4730:2004. Geneva, Switzerland. http://www.iso.org/iso/catalogue_detail.htm?csnumber=37033.
5. Carson CF, Riley TV. Antimicrobial activity of the major components of the essential oil of Melaleuca alternifolia. J Appl Bacteriol. 1995;78(3):264-269.7730203
6. Carson CF, Hammer KA, Riley TV. Broth micro-dilution method for determining the susceptibility of Escherichia coli and Staphylococcus aureus to the essential oil of Melaleuca alternifolia (tea tree oil). Microbios. 1995;82(332):181-185.7630326
7. 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;21(4):242-245.7576514
8. Bergstrom KG. Tea tree oil: panacea or placebo? J Drugs Dermatol. 2009;8(5):494-496.19537376
9. Hammer KA, Carson CF, Riley TV, Nielsen JB. A review of the toxicity of Melaleuca alternifolia (tea tree) oil. Food Chem Toxicol. 2006;44(5):616-625.16243420
10. Van Kessel K, Assefi N, Marrazzo J, Eckert L. Common complementary and alternative therapies for yeast vaginitis and bacterial vaginosis: a systematic review. Obstet Gynecol Surv. 2003;58(5):351-358.12719677
11. Enshaieh S, Jooya A, Siadat AH, Iraji F. The efficacy of 5% topical tea tree oil gel in mild to moderate acne vulgaris: a randomized, double-blind placebo-controlled study. Indian J Dermatol Venereol Leprol. 2007;73(1):22-25.17314442
12. Martin KW, Ernst E. Herbal medicines for treatment of bacterial infections: a review of controlled clinical trials. J Antimicrob Chemother. 2003;51(2):241-246.12562687
13. Caelli M, Porteous J, Carson CF, Heller R, Riley TV. Tea tree oil as an alternative topical decolonization agent for methicillin-resistant Staphylococcus aureus. J Hosp Infect. 2000;46(3):236-237.11073734
14. Dryden MS, Dailly S, Crouch M. A randomized, controlled trial of tea tree topical preparations versus a standard topical regimen for the clearance of MRSA colonization. J Hosp Infect. 2004;56(4):283-286.15066738
15. Thompson G, Blackwood B, McMullan R, et al. A randomized controlled trial of tea tree oil (5%) body wash versus standard body wash to prevent colonization with methicillin-resistant Staphylococcus aureus (MRSA) in critically ill adults: research protocol. BMC Infect Dis. 2008;8:161.19040726
16. Soukoulis S, Hirsch R. The effects of a tea tree oil-containing gel on plaque and chronic gingivitis. Aust Dent J. 2004;49(2):78-83.15293818
17. Arweiler NB, Donos N, Netuschil L, Reich E, Sculean A. Clinical and antibacterial effect of tea tree oil—a pilot study. Clin Oral Investig. 2000;4(2):70-73.11218503
18. Hammer KA, Carson CF, Riley TV. In vitro activities of ketoconazole, econazole, miconazole, and Melaleuca alternifolia (tea tree) oil against Malassezia species. Antimicrob Agents Chemother. 2000;44(2):467-469.10639388
19. Bagg J, Jackson MS, Petrina Sweeney M, Ramage G, Davies AN. Susceptibility to Melaleuca alternifolia (tea tree) oil of yeasts isolated from the mouths of patients with advanced cancer. Oral Oncol. 2006;42(5):487-492.16488180
20. 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(6):601-605.8195735
21. 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(4):284-287.10357864
22. Satchell AC, Saurajen A, Bell C, Barnetson RS. Treatment of interdigital tinea pedis with 25% and 50% tea tree oil solution: a randomized, placebo-controlled, blinded study. Australas J Dermatol. 2002;43(3):175-178.12121393
23. Tong MM, Altman PM, Barnetson RS. Tea tree oil in the treatment of tinea pedis. Australas J Dermatol. 1992;33(3):145-149.1303075
24. Satchell AC, Saurajen A, Bell C, Barnetson RS. Treatment of dandruff with 5% tea tree oil shampoo. J Am Acad Dermatol. 2002;47(6):852-855.12451368
25. Vazquez JA, Zawawi AA. Efficacy of alcohol-based and alcohol-free melaleuca oral solution for the treatment of fluconazole-refractory oropharyngeal candidiasis in patients with AIDS. HIV Clin Trials. 2002;3(5):379-385.12407487
26. Astani A, Reichling J, Schnitzler P. Comparative study on the antiviral activity of selected monoterpenes derived from essential oils. Phytother Res. 2010;24(5):673-679.19653195
27. Carson CF, Ashton L, Dry L, Smith DW, Riley TV. Melaleuca alternifolia (tea tree) oil gel (6%) for the treatment of recurrent herpes labialis. J Antimicrob Chemother. 2001;48(3):450-451.11533019
28. Khalil Z, Pearce AL, Satkunanathan N, Storer E, Finlay-Jones JJ, Hart PH. Regulation of wheal and flare by tea tree oil: complementary human and rodent studies. J Invest Dermatol. 2004;123(4):683-690.15373773
29. Pearce AL, Finlay-Jones JJ, Hart PH. Reduction of nickel-induced contact hypersensitivity reactions by topical tea tree oil in humans. Inflamm Res. 2005;54(1):22-30.15723201
30. 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. 2010;65(5):877-888.19680653
31. Gray SG, Clair AA. Influence of aromatherapy on medication administration to residential-care residents with dementia and behavioral challenges. Am J Alzheimers Dis Other Demen. 2002;17(3):169-174.12083347
32. Sadr Lahijani MS, Raoof Kateb HR, Heady R, Yazdani D. The effect of German chamomile (Marticaria recutita L.) extract and tea tree (Melaleuca alternifolia L.) oil used as irrigants on removal of smear layer: a scanning electron microscopy study. Int Endod J. 2006;39(3):190-195.16507072
33. Halcón L, Milkus K. Staphylococcus aureus and wounds: a review of tea tree oil as a promising antimicrobial. Am J Infect Control. 2004;32(7):402-408.15525915
34. Bronstein AC, Spyker DA, Cantilena LR Jr, Green J, Rumack BH, Heard SE. 2006 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS). Clin Toxicol (Phila). 2007;45(8):815-917.18163234
35. Blackwood B, Thompson G, McMullan R, et al.Tea tree oil (5%) body wash versus standard care (Johnson's Baby Softwash) to prevent colonization with methicillin-resistant Staphylococcus aureus in critically ill adults: a randomized controlled trial. J Antimicrob Chemother. 2013;68(5):1193-1199.2329739510.1093/jac/dks501
36. Joksimovic N, Spasovski G, Joksimovic V, Andreevski V, Zuccari C, Omini CF. 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 Surg. 2012;64(3):195-201.22492249
37. Wallengren J. Tea tree oil attenuates experimental contact dermatitis. Arch Dermatol Res. 2011;303(5):333-338.2086526810.1007/s00403-010-1083-y
38. Mowry JB, Spyker DA, Cantilena LR Jr, Bailey JE, Ford M. 2012 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 30th Annual Report. Clin Toxicol (Phila). 2013;51(10):949-1229.24359283
39. Christoffers WA, Blömeke B, Coenraads PJ, Schuttelaar ML. Co-sensitization to ascaridole and tea tree oil. Contact Dermatitis. 2013;69(3):181-191.23948040
40. Bhamarapravati S, Pendland SL, Mahady GB. Extractsof spice and food plants from Thai traditional medicine inhibit the growth of the human carcinogen Helicobacter pylori. In Vivo. 2003;17(6):541-544.14758718
41. Zaenglein AL, Pathy AL, Schlosser BJ, at al. Guidelines of care for the management of acne vulgaris. J Am Acad Dermatol. 2016;74(5):945-973.e33.26897386
42. Cao H, Yang G, Wang Y, Liu JP, Smith CA, Luo H, Liu Y. Complementary therapies for acne vulgaris. Cochrane Database Syst Rev. 2015;1:CD009436.25597924

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