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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-.

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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].

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Tea tree oil: a systematic review of randomized clinical trials

and .

Review published: .

Authors' objectives

To review the evidence from randomised controlled trials (RCTs) for or against the effectiveness of external tea tree oil (TTO) in dermatological conditions.

Searching

The following electronic databases were searched from inception to April 1999: MEDLINE, the Cochrane Library, EMBASE, BIOSIS Previews, the Science Citation Index and CISCOM. The search terms were: 'tea tree oil', 'Melaleuca alternafolia', 'essential oils', 'aromatherapy', 'herbal medicine', 'phytomedicine' and 'phytotherapy'. In addition, the authors' own database was searched, experts and manufacturers of commercial products containing TTO were contacted, and bibliographies of retrieved articles were examined. No language restrictions were reported.

Study selection

Study designs of evaluations included in the review

RCTs were included.

Specific interventions included in the review

In terms of the selection criteria for primary studies, all topical TTO preparations were eligible. In the included studies, the interventions were as follows: 5% water-based TTO gel, 10% TTO cream, 100% TTO, and 2% butenafine hydrochloride combined with 5% TTO as a cream. Control interventions were as follows: 5% benzoyl peroxide lotion, 1% tolnaftate cream, placebo cream, 1% clotrimazole solution, and placebo cream containing TTO (for studies versus 2% butenafine hydrochloride and 5% TTO cream).

Participants included in the review

Humans with dermatological conditions such as acne, tinea pedis, subungual onychomycosis and toenail onychomycosis.

Outcomes assessed in the review

The outcomes measures were not specified in terms of study selection criteria. Outcome measures used in the included studies were: total number of inflamed and noninflamed lesions (acne), skin tolerance, adverse events, conversion to negative culture (for tinea pedis and onychomycosis), change in clinical symptoms and regrowth of normal nail.

How were decisions on the relevance of primary studies made?

All studies were read by two independent reviewers, and any discrepancies were resolved through discussion.

Assessment of study quality

The methodological quality of all of the included studies was evaluated using the Jadad score (see Other Publications of Related Interest). All studies were read by two independent reviewers, and any discrepancies were resolved through discussion.

Data extraction

The following data were extracted in a standardised, predefined fashion: study reference, study design, Jadad score, study sample, patient demographics, experimental intervention, control intervention, main outcome measure and main results. The authors did not state how many reviewers performed the data extraction.

Methods of synthesis

How were the studies combined?

The studies were combined in a narrative summary.

How were differences between studies investigated?

Heterogeneity was not formally assessed, but the four included trials were tabulated and discussed separately.

Results of the review

Four RCTs (n=421) were included, of which 3 were of double-blind design .

Trial 1 (Jadad score 2; n=124).

Patients with mild-to-moderate acne were prescribed 5% water-based TTO gel or 5% water-based benzoyl peroxide lotion, both applied daily for 3 months. Lesions decreased with both treatments but inflamed lesions were significantly better with benzoyl peroxide compared with TTO; noninflamed lesions were comparable. Fewer patients experienced adverse events with TTO (44 versus 79%).

Trial 2 (Jadad score 3; n=120).

Patients with tinea pedis (proven by culture) were prescribed 10% TTO cream, 1% tolnaftate cream or placebo cream, all applied twice daily for 4 weeks. At the end of the treatment period, 30% of the TTO group, 85% of the tolnaftate group and 21% of the placebo group had negative cultures (non significant difference between TTO and placebo), and clinical improvement was experienced by 65, 58 and 41%, respectively (the difference between TTO and placebo was statistically significant). No adverse events were reported.

Trial 3 (Jadad score 5; n=117).

Patients with subungual onychomycosis received either 100% TTO or 1% clotrimazole twice daily for 6 months. At the end of trial, 18% of TTO-treated patients and 11% of control patients had negative cultures. Full or partial resolution of symptoms was experienced by 60 and 61% of patients, respectively. At 3-month follow-up, these figures had declined to 56 and 55%, respectively. None of these differences were statistically significant.

Trial 4 (Jadad score 4; n=60).

Patients received either 2% butenafine hydrochloride and 5% TTO cream or a cream of TTO only for toenail onychomycosis, applied thrice daily for 8 weeks. The overall cure rates (resolution of clinical symptoms, negative culture, and progressive growth of normal nail) at 9 months were 80% for the combined cream and 0% for controls. Four patients in the combined cream group experienced mild inflammation.

Authors' conclusions

There is no compelling evidence to show that TTO is efficacious in any dermatological condition. However, in view of promising findings, TTO deserves to be investigated more closely.

CRD commentary

Adequate details were given of the selection criteria for primary studies, the search strategy was thorough, and validity assessment was performed with reference to a published checklist. Some details of trials were provided in the text and tables, but it would have been useful if the p-values for between-group comparisons had also been shown. In addition, more details of the methodological quality of each individual trial would have been useful. The use of narrative summary for data synthesis was appropriate given the clinical heterogeneity across trials. Two independent reviewers were involved in selecting and assessing studies, but it is unclear how many were involved in data extraction. The authors' cautious conclusions seem appropriate given the quality and quantity of data presented.

Implications of the review for practice and research

Practice: The authors stated 'Since TTO is by no means free of adverse effects, its indiscriminate use should not be encouraged'.

Research: The authors stated 'Future RCTs should be encouraged and should overcome the methodological problems of the trials published so far'.

Bibliographic details

Ernst E, Huntley A. Tea tree oil: a systematic review of randomized clinical trials. Forschende Komplementarmedizin und Klassische Naturheilkunde 2000; 7(1): 17-20. [PubMed: 10800248]

Other publications of related interest

Jadad AR, Moore RA, Carroll D, Jenkinson C, Reynolds DJ, Gavaghan DJ, et al. Assessing the quality of reports of randomized clinical trials: is blinding necessary? Control Clin Trials 1996;17:1-12.

Indexing Status

Subject indexing assigned by NLM

MeSH

Administration, Topical; Anti-Infective Agents, Local /therapeutic use; Complementary Therapies; Humans; Randomized Controlled Trials as Topic; Skin Diseases /drug therapy; Tea Tree Oil /administration & dosage /therapeutic use

AccessionNumber

12000001396

Database entry date

31/12/2001

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.

Copyright © 2014 University of York.
Bookshelf ID: NBK68347

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