In recognition of foot health month, the status of tea tree oil as an antimicrobial agent is reviewed. Tea tree oil shows great promise as an antifungal and antibacterial product. This includes topical infections of foot and toe nails.

1. NMR News: Volume 3, Issue 4, April 2010
Evidence Supporting Usage of Tea Tree
Oil for Topical Infections of the Foot and
Other Areas is Promising, but Ongoing
Research Needed
By: Charles Spielholz, Ph.D.
T
clinical trials indicate that tea tree oil may be
he tea tree (Melaleuca alternifolia) is
useful for the treatment of certain topical
a shrub-like tree native to Australia
infections, particularly infections that are
where it grows in
caused by fungi. However,
wet areas. The oil isolated
tea tree oil has not been
from the leaves of this tree
subjected to rigorous
by a process of steam
clinical trials. A short
distillation has been
review of the status of the
associated, in traditional
antimicrobial activity of tea
medicine, with
tree oil is provided.
antimicrobial properties.
Questions that need to be
Microbial species thought
answered through
to be sensitive to tea tree
appropriate biomedical
oil include fungal,
research approaches are
bacterial, protozoan and
also discussed.
viral species. Preliminary data and pilot
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2. NMR News: Volume 3, Issue 4, April 2010
Fungal infections that are believed to be preliminary clinical trials (4-6). These results
susceptible to tea tree oil include those that are very promising and indicate a role for
cause athlete's foot (tinea pedis), finger and tea tree oil as an agent for topical infections.
toe nail infections (onychomychosis), jock Appropriately designed studies should be
itch (tinea cruris), thrush (Candidiasis) as able to establish a systematic approach to
well as others. Preliminary studies indicate the use of tea tree oil for topical fungal
that tea tree oil infections.
has antifungal
activity and may There have been
be a good several reports in the
candidate as a scientific literature
topical agent for that show tea tree oil
treatment of may be effective
fungal infections. against a wide variety
Reports in the of bacteria in vitro (7-
scientific 9). Most clinical trials
literature have shown that tea tree oil has using tea tree oil as a topical antibacterial
activity against Candidiasis in vitro (1, 2). In a have mostly centered on acne (10, 11) and
preliminary clinical study, tea tree oil was infections in the mouth (12, 13). Gels
successfully used to treat toe nail containing tea tree oil designed for the care
onychomychosis (3). Tea tree oil was a of teeth have been shown to decrease
component of a topical cocktail used in an gingivitis and gum bleeding (14), but did
approach to treat athlete's foot in not reduce plaque (14). (Note that tea tree oil
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3. NMR News: Volume 3, Issue 4, April 2010
is toxic when ingested and therefore it is not Experiments designed to elucidate
recommended that pure tea tree oil be used the mechanism of action of tea tree oil
orally). Antibacterial studies using tea tree against both bacteria and fungi indicate that
oil are in the early stage and are not as the oil may be disrupting the function of
advanced at the antifungal studies; however lipid membranes and causing alterations in
results indicate that it is worth pursuing this the transport of potassium ions and the
research. metabolism of glucose in respiration (17-22).
A basic understanding of an agent’s
Very little data has been collected mechanism of action helps support the
that shows that tea tree oil has activity clinical observations.
against protozoan and viral species. The
only work that has been done in this regard The safety and toxicity of tea tree oil
is in vitro (15,16); there have been no has not been well studied (23). Tea tree oil is
published reports showing that tea tree oil toxic if taken orally. Such toxicity is
has anti- protozoan or anti-viral activity in expected of any functional antifungal agent
an animal model or similar living system. and will not limit the oils usefulness as a
More importantly, there has been no work topical antifungal agent. Indeed, the oil
performed on the purported anti- protozoan appears to be safe to use topically, at least
or anti-viral activity of tea tree oil in the past when dilute,
decade. No significant clinical work has although it has
been done using tea tree oil as an anti- been observed
protozoan or anti-viral agent. to cause allergic
skin reactions
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4. NMR News: Volume 3, Issue 4, April 2010
in some individuals. The effect of tea tree oil approach to treating topical infections,
on the fetus and in growing children is not especially fungal infections that have
known; therefore tea tree oil should not be become resistant to antifungal medications
used in children or by pregnant or nursing currently on the market; therefore it is well
women. A complete picture of tea tree oil’s worth the effort to complete these studies.
adverse will become clear as additional
clinical trials are completed. References
1) D'Auria FD, Laino L, Strippoli V, Tecca M, Salvatore G,
Evidence indicates that there may be Battinelli L, Mazzanti G. 2001. In vitro activity of tea tree oil
against Candida albicans mycelial conversion and other
a role for tea tree oil as a topical agent for pathogenic fungi. J Chemother. 13:377-383.
fungal and bacterial infections. Additional 2) Ergin A, Arikan S. 2002. Comparison of microdilution
and disc diffusion methods in assessing the in vitro activity
clinical trials should be able to establish the of fluconazole and Melaleuca alternifolia (tea tree) oil
against vaginal Candida isolates. J Chemother. 14:465-472.
precise conditions, including which fungal
3) Syed TA, Qureshi ZA, Ali SM, Ahmad S, Ahmad SA.
and bacterial species, the optimal dosages, 1999. Treatment of toenail onychomycosis with 2%
butenafine and 5% Melaleuca alternifolia (tea tree) oil in
and the time course of treatment required cream. Trop Med Int Health. 1999. 4:284-287.
for maximum efficacy of tea tree oil for 4) Misner BD. 2007. A novel aromatic oil compound
inhibits microbial overgrowth on feet: a case study. J Int
topical infections. A clear definition of all Soc Sports Nutr. 4:3.
adverse effects could also b established. 5) Inouye S, Uchida K, Nishiyama Y, Hasumi Y, Yamaguchi
H, Abe S. 2007. Combined effect of heat, essential oils and
Such clinical trials would need to be salt on fungicidal activity against Trichophyton
mentagrophytes in a foot bath. Nippon Ishinkin Gakkai
designed and carried out before tea tree oil Zasshi. 48:27-36.
can be widely recommended for use as a 6) Inouye S, Nishiyama Y, Uchida K, Hasumi Y, Yamaguchi
H, Abe S. 2006. The vapor activity of oregano, perilla, tea
remedy for topical infections. It appears that tree, lavender, clove, and geranium oils against a
Trichophyton mentagrophytes in a closed box. J Infect
tea tree oil may have potential as a useful Chemother. 12:349-354.
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5. NMR News: Volume 3, Issue 4, April 2010
7) Carson CF, Riley TV. 1993. Antimicrobial activity of the 18) Cox SD, Mann CM, Markham JL, Bell HC, Gustafson JE,
essential oil of Malaleuca alternifolia. Lett. Appl. Microbiol. Warmington JR, Wyllie SG. 2000. The mode of
16: 49-55. antimicrobial action of the essential oil of Melaleuca
alternifolia (tea tree oil). J Appl Microbiol. 88:170-175.
8) Carson CF, Riley TV. 1995. Antimicrobial activity of the
major components of the essential oil of Melaleuca 19) Hada T, Inoue Y, Shiraishi A, Hamashima H. 2003.
alternifolia. J Appl Bacteriol. 78:264-269. Leakage of K+ ions from Staphylococcus aureus in
response to tea tree oil. J Microbiol Methods. 53:309-312.
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Antimicrob Chemother. 35:421-424. components on Candida albicans, Candida glabrata and
Saccharomyces cerevisiae. J Antimicrob
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acne treatments. Semin Cutan Med Surg. 27:170-176.
21) Cox SD, Mann CM, Markham JL, Bell HC, Gustafson JE,
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treatment of bacterial infections: a review of controlled antimicrobial action of the essential oil of Melaleuca
clinical trials. J Antimicrob Chemother.51:241-246. alternifolia (tea tree oil). J Appl Microbiol. 88:170-175.
12) Arweiler NB, Donos N, Netuschil L, Reich E, Sculean A. 22) Inouye S, Watanabe M, Nishiyama Y, Takeo K, Akao M,
2000. Clinical and antibacterial effect of tea tree oil--a pilot Yamaguchi H. 1998. Antisporulating and respiration-
study. Clin Oral Investig. 4:70-73. inhibitory effects of essential oils on filamentous fungi.
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containing gel on plaque and chronic gingivitis. Aust Dent
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In vitro effect of essential oils and isolated mono- and
sesquiterpenes on Leishmania major and Trypanosoma
brucei. Planta Med. 66:366-368.
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YC, Hartland RP, Bell HC, Warmington JR, Wyllie SG.
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in Escherichia coli. Lett Appl Microbiol. 26:355-358.
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