Australasian Journal of Dermatology
Treatment of interdigital tinea pedis with 25%
and 50% tea tree oil solution: A randomized,
Andrew C Satchell,1 Anne Saurajen,1 Craig Bell2 and Ross StC Barnetson1
1Department of Dermatology, Royal Prince Alfred Hospital, Camperdown and
2Australian Tea Tree Oil Research Institute, Southern Cross University, Lismore,
and Epidermophyton floccosum
, and appears to be related to occlusive footwear.2 Tinea pedis occurs as one of four
clinical variants: intertriginous, papulosquamous, vesicular
Tea tree oil has been shown to have activity against
and acute ulcerative.3 Chronic, intertriginous tinea pedis is
dermatophytes in vitro
. We have conducted a random-
characterized by a scaling and fissuring of the lateral toe
ized, controlled, double-blinded study to determine the
webs caused by dermatophyte invasion of the stratum
efficacy and safety of 25% and 50% tea tree oil in
corneum; macerated, erosive infections may follow as a result
the treatment of interdigital tinea pedis. One hundred
of secondary overgrowth of commensal bacteria, including
and fifty-eight patients with tinea pedis clinically and
Micrococcaceae (usually staphylococci), aerobic coryneforms
microscopy suggestive of a dermatophyte infection
and Gram-negative organisms.4 Microscopy and culture of
were randomized to receive either placebo, 25% or 50%
skin scrapings are used to identify the relevant organism.
tea tree oil solution. Patients applied the solution twice
The treatment of intertiginous tinea pedis includes
daily to affected areas for 4 weeks and were reviewed
measures aimed at reducing hyperhidrosis, such as talcum
after 2 and 4 weeks of treatment. There was a marked
powder and wearing open-toed shoes. Topical antibacterial
clinical response seen in 68% of the 50% tea tree oil
measures such as 25% acetic acid soaks and colourless
group and 72% of the 25% tea tree oil group, compared
Castellani’s paint (phenolated resorcinol) are helpful in
to 39% in the placebo group. Mycological cure was
treating macerated infections.5 Topical antifungal treatments
assessed by culture of skin scrapings taken at baseline
for interiginous tinea pedis include tolnaftate, the imidazoles
and after 4 weeks of treatment. The mycological cure
and terbinafine; short-term oral treatments include itracona-
rate was 64% in the 50% tea tree oil group, compared
zole 400 mg daily for 1 week and terbinafine 250 mg daily
to 31% in the placebo group. Four (3.8%) patients
applying tea tree oil developed moderate to severe
Tea tree oil (melaleuca oil) is an essential oil extracted
dermatitis that improved quickly on stopping the
primarily from the leaves of Melaleuca alternifolia
, a shrub-
like tree native to northern New South Wales and southernQueensland. Tea tree oil has antimicrobial properties and has
Key words: athlete’s foot, melaleuca oil, natural
been used as a natural remedy for a variety of skin complaints
for many years. During World War I, tea tree oil was includedin the first-aid kits of Australian troops to treat burns, bites,and infections. Tea tree oil is widely available in Australianpharmacies and natural therapy stores in various prepar-
ations, including antifungal gel 50 mg/g, acne gel 200 mg/g,
Tinea pedis is a dermatophyte infection of the feet or toes
antiseptic cream 50 mg/mL, antiseptic solution 15% and
affecting 10% of the population at any given time.1 It is most
100%, head lice solution 10%, insect repellant 18.9 mg/mL and
commonly caused by Trichophyton rubrum, T. mentagrophytes
shampoo and conditioner. Clinical studies have suggested teatree oil is effective in treating tinea pedis,7 onychomycosis8trichomonal vaginitis,9 acne10 and dandruff.11
Correspondence: Professor RStC Barnetson, Department of
Tea tree oil is a complex mixture of hydrocarbons
Dermatology, Royal Prince Alfred Hospital, Camperdown NSW 2050,
and terpenes, consisting of almost 100 substances, and
Australia. Email: [email protected]
the antimicrobial activity appears to be related to the
Andrew C Satchell, MB BS. Anne Saurajen, MB BS. Craig Bell, PhD.
major component, terpinen-4–0 L,12 which accounts for
Submitted 8 October 2001; accepted 3 January 2002.
one-third of the final volume of tea tree oil. The minimum
inhibitory concentration of tea tree oil for T. rubrum
Patients were randomized to receive either placebo (20%
volume/volume and T. mentagrophytes
ethanol, 80% polyethylene glycol), or 25% or 50% tea tree oil
mixed in ethanol and polyethylene glycol solution. They were
The activity of tea tree oil against dermatophytes prompted
instructed to wash their feet with soap and water, dry between
our department to trial its use in tinea pedis. In an earlier study
the toes and apply the solution to the affected areas twice daily
of 104 patients randomly assigned to receive either 10% tea
for 4 weeks. They were given advice about the wearing of open
tree oil cream, tolnafate 1% cream or placebo, we found that
footwear and requested not to use other antifungal treatments.
10% tea tree oil cream significantly improved the condition
The patients were reviewed at weeks 2 and 4 of the treat-
clinically, but the mycological cure rate, while improved,
ment. At each visit an assessment was made of scaling and
was not significantly greater than placebo.7 Therefore, it was
inflammation by the investigator, and burning and itching
considered that an increased concentration of tea tree oil
by the patient. Each of these was graded as absent, mild,
might be more effective in achieving mycological cure. At
moderate, severe or very severe and given a corresponding
high concentrations tea tree oil is not stable in a cream. In
score of 0–4; the four scores added together to give the
this study we have compared 25% and 50% tea tree oil with
‘clinical score’. Assessments were made without referring
placebo in a randomized, double-blind study of patients with
back to previous scores. A marked clinical response was
considered to be a reduction of three or more in the clinicalscore to a final value less than three, or a final value of zero.
The mycological cure rate was determined from culture of skin scrapings taken at baseline and at the end of the 4-week
The study was approved by the Ethics Review Committee of
treatment period. ‘Effective cure’ was considered to be both a
the Royal Prince Alfred Hospital in Sydney, Australia, and
marked clinical response and mycological cure.
informed consent was obtained. One hundred and fifty-eight
It was anticipated that at least one of the tea tree oil groups
patients, aged 14 or older, with typical clinical features of
would have a response rate of at least 60%, and it was assumed
intertriginous tinea pedis were recruited by advertising in local
there would be a 20% response rate in the placebo group. In
newspapers. A skin scraping was taken for microscopy and
order to be able to declare this difference as statistically differ-
culture and only those with microscopy suggestive of a
ent at the 0.025 level, it was determined that there should be
dermatophyte infection were enrolled into the study. Patients
32 patients in each treatment group. It was also assumed,
excluded from the study were those treated with systemic
based on previous work by this department, that approxi-
antifungals within the preceding 6 months or topical anti-
mately 40% of patients who present with positive microscopy
fungals within the preceding 7 days, and those with derma-
will have a negative culture for dermatophyte infection. As the
titis, immunosuppression or a history of hypersensitivity to tea
culture takes approximately 2–4 weeks to grow, all patients
with a positive microscopy were enrolled in the study, but only
Mycologic response at the end of 4 weeks treatment
Clinical response at the end of 4 weeks treatment
those patients who later showed a positive culture for dermato-
tree oil and three patients applying 50% tea tree oil, one of
phytes were included in the evaluation. Thus, a sample of
whom was withdrawn from the study. These dermatitis reac-
54 patients per treatment group was chosen to ensure at least
tions responded quickly to stopping the study medication
32 patients with confirmed dermatophyte infections in each
and topical corticosteroids were used in two patients. Stinging
group. The significance of the differences between the 25% tea
on application was reported in two patients applying 25% tea
tree oil group, the 50% tea tree oil group and the placebo group
tree oil and two patients applying placebo, and was described
was assessed using the χ-squared test. P
values of <0.05 were
as mild, lasting for a few seconds. There were no serious
There were 158 patients enrolled into the study, of whom 104
There has been increasing interest in the use of natural ther-
(66%) were male and 54 (34%) were female. Their ages ranged
apies. Tea tree oil is one such product and is already widely
from 17 to 83, with a mean age of 41 years. There were
available in Australia for the treatment of superficial infections
53 patients randomized to the placebo group, 54 to the 25%
tea tree oil group and 51 to the 50% tea tree oil group.
One clinical study performed by our group has already
The three groups were similar in sex distribution, mean age,
shown that 10% tea tree oil cream was effective in improving
baseline clinical scores and skin scraping culture results
the tinea clinically, although the mycological cure rate was not
significantly better than placebo.7 In order to improve the
All 158 enrolled into the study had typical clinical features
mycological cure rate, we have used higher concentrations
of tinea pedis, as well as microscopy suggestive of a dermato-
(25% and 50%) of tea tree oil, prepared in solution rather than
phyte infection. However, only 137 (86.7%) patients sub-
as a cream because of the immiscibility of tea tree oil in
sequently cultured a dermatophyte: 49 (92.5%) in the placebo
group, 43 (79.6%) in the 25% tea tree oil group and 45 (88.2%)
The study was conducted as a double-blind study, although
of the 50% tea tree oil group. Of the 137 patients with a
it could be argued that the study was single-blinded because
confirmed dermatophyte infection, 120 (87.6%) completed
the distinctive odour of tea tree oil identifies it to the patient.
the study. One patient in the 50% tea tree oil group was with-
However, this information was not volunteered to the patients,
drawn because of an adverse reaction and 16 patients were
and it is not possible to distinguish between 25% and 50% tea
lost to follow up: three (2.19%) in the placebo group, seven
(5.11%) in the 25% tea tree oil group and six (4.38%) in the
Of the 158 patients with clinically apparent tinea pedis and
50% tea tree oil group. The higher loss to follow up in the tea
skin scrapings demonstrating fungal elements on microscopy,
tree oil groups was not statistically significant (P
a dermatophyte was cultured in 137 (87%). This was higher
Mycological cure could be determined for 114 of the 120
than expected based on previous work in this department.14
patients who completed the study: six patients (one placebo,
Only those patients who remained in the study and had a
three 25% and two 50% tea tree oil) did not have follow-up
repeat skin scraping (114 patients) could be used to determine
skin scrapings taken. Mycological cure was achieved in 18
the cure rate. The rate of loss was higher in the tea tree oil
(55%) of the 25% tea tree oil group and 23 (64%) of the 50%
groups, although this was not statistically significant. It would
tea tree oil group, compared with 14 (31%) in the placebo
be reasonable, then, to draw conclusions based on the results
group (Table 2). The higher mycological cure rate in the tea
of only those patients completing the study.
tree oil groups was statistically significant (P
Mycological cure rates of 55% and 64% in the 25% and 50%
The number of patients with a marked improvement in the
tea tree oil groups, respectively, are somewhat lower than
clinical score (a final clinical score of zero or a reduction of
those obtained for clotrimazole (90%) and terbinafine (90%)
three or more to a final value less than three) was also signifi-
in similarly designed studies.14 The mycological response
cantly higher in the tea tree oil groups compared with placebo
observed in the placebo group (31%) was not unexpected,
(Table 3). Marked improvement in the clinical score was seen
because all patients were asked to wash their feet with soap
in 26 (72%) of the 25% tea tree oil group and 26 (68%) of the
and water and dry between the toes before applying the
50% tea tree oil group, compared with 18 (39%) in the placebo
solution, and were given advice about wearing open footwear.
group. This too was statistically significant (P
< 0.005). The
The effective cure rate, which required both a marked
clinical severity score fell 68% and 66% in the 25% and 50%
clinical improvement and mycological cure, was seen in
tea tree oil groups, respectively, compared with 41% in the
48% of the 25% tea tree oil group and 50% of the 50% tea tree
oil group; both significantly better than the placebo group
Effective cure, defined as both mycological cure and marked
(13%). Again, these rates are lower than for standard topical
clinical response, was again higher in the tea tree oil groups:
treatments. Three studies, each with a similar design to this
16 (48%) in the 25% tea tree oil group, 18 (50%) in the 50%
one, have been reviewed.14 These studies compared clotri-
tea tree oil group and 6 (13%) in the placebo group
mazole with terbinafine and estimated that the average
effective cure rate for subjects applying clotrimazole was
All patients enrolled in the study, including those without
63% (95% confidence interval (CI) = 56–69%) and terbinafine
dermatophyte infections, were included in the safety popu-
lation. Dermatitis occurred in one patient applying 25% tea
Dermatitis occurred in four (3.8%) patients treated with tea
tree oil. It is unclear whether these were irritant or allergic
Fitzpatrick’s Dermatology in General Medicine
, Vol. 2, 5th edn.
reactions. All reactions developed after 2 weeks and patch
New York: McGraw-Hill, 1999; 2337–57.
testing was not done. While it has been reported that 25% tea
4. Leyden JL. Tinea pedis pathophysiology and treatment. J. Am.
tree oil is not an irritant,11 there is no published information
5. Smith EB. Topical antifungal drugs in the treatment of tinea pedis,
regarding the irritancy of 50% tea tree oil.
tinea cruris, and tinea corporis. J. Am. Acad. Dermatol.
Tea tree oil has been reported to cause allergic contact
dermatitis, although there are only a few reports,16–18 despite
6. Tausch I, Decroix J, Gwiezdzinski Z, Urbanowski S, Baran E,
its popularity and the fact that it is often applied to already
Ziarkiewicz M, Levy G, Del Palacio A. Short-term itraconazole
irritated or broken skin. Interestingly, in patch testing of 28
versus terbinafine in the treatment of tinea pedis or manus.
normal volunteers, it was found that three volunteers reacted
Int. J. Dermatol.
7. Tong MM, Altman PM, Barnetson RStC. Tea tree oil in the
strongly to 25% tea tree oil, and all three patients subsequently
treatment of tinea pedis. Australas. J. Dermatol.
reacted strongly to preparations containing sesquiterpenoid
8. Buck DS, Nidorf DM, Addino JG. Comparison of two topical
fractions of the oil.18 This suggests allergic contact dermatitis
preparations for the treatment of onychomycosis: Melaleuca
is not uncommon. Reported allergens within tea tree oil
alternifolia (tea tree) oil and clotrimazole. J. Fam. Prac.
include monoterpenes such as terpinen-4-ol, D-limonene and
α-terpinene, the sesquiterpenoid fraction and 1,8 cineol.
9. Pena EF. Melaleuca alternifolia oil, uses for trichomonal
vaginitis and other vaginal infections. Obstet. Gynaecol.
In summary, we have found in a large, randomized,
placebo-controlled study that both 25% and 50% tea tree oil
10. Bassett IB, Pannowitz DL, Barnetson RStC. A comparative study
solutions are effective in treating tinea pedis, and that 25% tea
of tea-tree oil versus benzoylperoxide in the treatment of acne.
tree oil is associated with fewer complications than 50% tea
Med. J. Aust.
tree oil solution. We recommend that 25% tea tree oil be
11. Satchell AC, Saurajen A, Bell C, Barnetson RStC. Treatment of
considered in those patients keen to use natural agents in
dandruff with 5% tea tree oil shampoo. J. Am. Acad. Dermatol.
: In press.
the treatment of tinea pedis, although 25% tea tree oil is less
12. Carson CF, Riley TV. Antimicrobial activity of the major com-
effective than standard topical treatments.
ponents of the essential oil of Melaleuca alternifolia
. J. Appl.
13. Griffin SG, Markham JL, Leach DN. An agar dilution method for
the determination of the minimum inhibitory concentration of
essential oils. J. Essent. Oil Res.
This research was funded by the Australian Tea Tree Oil
14. Patel A, Brookman SD, Bullen MU, Marley J, Ellis DH, Williams
T, Barnetson RStC. Topical treatment of interdigital tinea pedis:
Terbinafine compared with clotrimazole. Austral. J. Dermatol.
15. Southwell IA, Freeman S, Rubel DM. Skin irritancy of tea tree oil.
J. Essent. Oil Res.
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16. Apted JH. Contact dermatitis associated with the use of tea-tree
tinea pedis in the community. Australas. J. Dermatol.
oil (letter). Australas. J. Dermatol.
17. Knight TE, Hausen BM. Melaleuca oil (tea tree oil) dermatitis.
2. Odom R. Pathophysiology of dermatophyte infections. J. Am. Acad.
J. Am. Acad. Dermatol.
18. Rubel DM, Freeman S, Southwell IA. Tea tree oil allergy: What
3. Martin AG, Kobayashi GS. Superficial fungal infection:
is the offending agent? Report of three cases of tea tree oil
Dermatophytosis, tinea nigra, piedra. In: Freedberg IM, Eisen AZ,
allergy and review of the literature. Australas. J. Dermatol.
Wolff K, Austen KF, Goldsmith LA, Katz SI, Fitzpatrick TB (eds).
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