Given the potential side effects of oral antifungal medications and the cost associated with topical antifungals, many patients have sought alternative modalities for the treatment of onychomycosis. Patients have often used tea tree oil as an alternative treatment modality for onychomycosis. Essential oils were often in use prior to the development of antimicrobial agents. Authors have proven that tea tree oils have antimicrobial, antifungal, antiviral and anti-inflammatory properties.1,2

Several studies have shown that tea tree oil has antifungal properties.3-5 The majority of research has focused on the use of tea tree oil in the treatment of Candida infections.6 These studies have demonstrated that tea tree oil is a successful treatment for numerous Candida infections, including azole-resistant yeasts and Candida biofilms.5,6 Research has additionally shown tea tree oil to be a successful treatment for dermatitis, ringworm (Trichophyton equinum) and stomatitis.7-9 

There is a poor understanding of the mechanism of activity for tea tree oil. Authors have suggested that lipophilic compounds in essential oils disrupt cell membranes.10 Straede and colleagues found that tea tree oil destabilizes cell membranes, resulting in fungal cell death.11 Additionally, studies have shown that essential oils enhance the permeation and retention of drugs within the skin.12,13 This also highlights the possibility that tea tree oil may be a successful adjunct to aid in the delivery of other antifungal medications. Several studies have shown a synergistic effect with the combination of tea tree oil with antifungal medications.14,15 

Little data exists on the use of tea tree oil in the treatment of onychomycosis. Studies have demonstrated that tea tree oil has in vitro antifungal activity against Trichophyton rubrum, the most common causative agent of onychomycosis.16

Misner found that a topical compound of essential oils, containing tea tree oil, was able to completely inhibit aerobic bacteria, yeast and fungi proliferation on the feet in an in-shoe environment.17

Syed and coworkers conducted a double-blind, placebo-controlled study examining the clinical efficacy and tolerability of 2% butenafine hydrochloride (Lotrimin, Bayer) and 5% tea tree oil compounded cream for the treatment of onychomycosis.18 They reported an 80 percent success rate at 16 weeks with the use of butenafine hydrochloride and tea tree oil cream. Mild inflammation surrounding the nail bed occurred in approximately 6 percent of the active treatment group.

Buck and colleagues compared the efficacy of tea tree oil and clotrimazole in the treatment of onychomycosis.19 This double-blind, multicenter, randomized, controlled trial of 117 patients found cure rates of 11 percent in the clotrimazole treated group and 18 percent in the tea tree oil group. Clinical assessment showed partial to full resolution in approximately 60 percent of the patients in both treatment groups.

Recently, Flores and coworkers evaluated the antifungal efficacy of tea tree oil in an onychomycosis model.20 In this study, nanocapsule suspensions containing tea tree oil reduced T. rubrum growth. 

Onychomycosis is the most common toenail disease but treatment remains difficult due to the potential side effects associated with oral antifungal medication, and the high cost and lower efficacy of newer topical antifungal agents. Tea tree oil may offer a cost-effective alternative to commonly used topical antifungal drugs. Additionally, further research is needed to examine whether tea tree oil can enhance the penetration of antifungal medication into the nail plate and may provide a synergistic effect with topical antifungal drugs in the treatment of onychomycosis.

References

1.      Low WL, Kenward K, Britland ST, Amin MC, Martin C. Essential oils and metal ions as alternative antimicrobial agents: a focus on tea tree oil and silver. Int Wound J. 2016; epub May 5.

2.      Cowan MM. Plant products as antimicrobial agents. Clin Microbiol Rev. 1999;12(4):564-582.

3.      Hammer KA, Carson CF, Riley TV. Antifungal activity of the components of Melaleuca alternifolia (tea tree) oil. J Appl Microbiol. 2003;95(4):853-860.

4.      Hammer KA, Carson CF, Riley TV. Antifungal effects of Melaleuca alternifolia (tea tree) oil and its components on Candida albicans, Candida glabrata and Saccharomyces cerevisiae. J Antimircob Chemother. 2004;53(6):1081-1085.

5.      Ramage G, Milligan S, Lappin DF, et al. Antifungal, cytotoxic, and immunomodulatory properties of tea tree oil and its derivative components: potential role in management of oral candidosis in cancer patients. Front Microbiol. 2012;3:220.

6.      Mondello F, De Bernardis F, Girolamo A, Salvatore G, Cassone A. In vitro and in vivo activity of tea tree oil against azole-susceptible and -resistant human pathogenic yeasts. J Antimircob Chemother. 2003;51(5):1223-1229.

7.      Wallengren J. Tea tree oil attenuates experimental contact dermatitis. Arch Dermatol Res. 2011;303(5):333-338.

8.      Pisseri F, Bertoli A, Nardoni S, et al. Antifungal activity of tea tree oil from Melaleuca alternifolia against Trichophyton equinum: an in vivo assay. Phytomedicine. 2009;16(11):1056-1058.

9.      Pachava KR, Nadendla LK, Alluri LS, Tahseen H, Sajja NP. Invitro antifungal evaluation of denture soft liner incorporated with tea tree oil: a new therapeutic approach towards denture stomatitis. J Clin Diagn Res. 2015;9(6):ZC62-64.

10.    Karpanen TJ, Worthington T, Hendry ER, Conway BR, Lambert PA. Antimicrobial efficacy of chlorhexidine digluconate alone and in combination with eucalyptus oil, tea tree oil and thymol against planktonic and biofilm cultures of Staphylococcus epidermidis. J Antimircob Chemother. 2008;62(5):1031-1036.

11.    Straede A, Corran A, Bundy J, Heinisch JJ. The effect of tea tree oil and antifungal agents on a reporter for yeast cell integrity signalling. Yeast. 2007;24(4):321-334.

12.    Fang JY, Leu YL, Hwang TL, Cheng HC. Essential oils from sweet basil (Ocimum basilicum) as novel enhancers to accelerate transdermal drug delivery. Biol Pharm Bull. 2004;27(11):1819-1825.

13.    Biruss B, Kahlig H, Valenta C. Evaluation of an eucalyptus oil containing topical drug delivery system for selected steroid hormones. Int J Pharm. 2007;328(2):142-151.

14.    Rosato A, Vitali C, Gallo D, Balenzano L, Mallamaci R. The inhibition of Candida species by selected essential oils and their synergism with amphotericin B. Phytomedicine. 2008;15(8):635-638.

15.    Mertas A, Garbusinska A, Szliszka E, Jureczko A, Kowalska M, Krol W. The influence of tea tree oil (Melaleuca alternifolia) on fluconazole activity against fluconazole-resistant Candida albicans strains. Biomed Res Int. 2015;2015:590470.

16.    Barchiesi F, Silvestri C, Arzeni D, et al. In vitro susceptibility of dermatophytes to conventional and alternative antifungal agents. Med Mycol. 2009;47(3):321-326.

17.    Misner BD. A novel aromatic oil compound inhibits microbial overgrowth on feet: a case study. J Int Soc Sports Nutr. 2007;4:3.

18.    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;4(4):284-287.

19.    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.

20.    Flores FC, de Lima JA, Ribeiro RF, et al. Antifungal activity of nanocapsule suspensions containing tea tree oil on the growth of Trichophyton rubrum. Mycopathologia. 2013;175(3-4):281-286.