ReviewTreatment of acne with tea tree oil (melaleuca) products: A review of efficacy, tolerability and potential modes of action
Introduction
Acne is viewed as a chronic inflammatory skin disorder caused by a combination of factors, including excessive sebum production, abnormal desquamation of the follicular epithelium, inflammation and the presence of the bacterium Propionibacterium acnes [1], [2]. Acne affects primarily adolescents and young adults, with up to 90% of adolescents affected by acne at some stage [3]. In addition, ca. 5% of adults suffer from persistent or late-onset acne [4], [5]. Aside from physical effects such as discomfort and potential scarring, acne can cause emotional and psychological stress to sufferers [6].
Despite the prevalence of acne, studies show that <20% of adolescents with acne seek help from medical professionals [7], [8]. Instead, individuals either do not treat their acne or self-treat with over-the-counter (OTC) products [7], [9]. Since acne treatments containing tea tree oil are available without a prescription, it is difficult to gauge their level of use, and very few studies have quantified this. One recent publication, which used an online crowdsourcing data collection technique, found tea tree oil to be the second most commonly used topical treatment, closely following the most commonly used product of 2.5% benzoyl peroxide [10]. This indicates that tea tree oil products are a relatively common choice for those self-treating their acne. Therefore, the aim of this review was to examine the efficacy, safety and tolerability of tea tree oil products for treating acne and to discuss potential modes of therapeutic action.
Section snippets
Tea tree oil
Tea tree oil, also known as melaleuca oil, is a monoterpene-rich, lipophilic, essential oil derived by steam distillation from the Australian native plant Melaleuca alternifolia (Myrtaceae). The oil contains ca. 100 components, with the most abundant component (terpinen-4-ol) typically comprising ca. 40% of the oil. Tea tree oil has broad-spectrum antimicrobial activity, and non-specific cell membrane damage is a major mechanism of antibacterial action [11]. Clinical studies with tea tree oil
Clinical efficacy of tea tree oil products
An extensive literature search found seven publications [15], [16], [17], [18], [19], [20], [21] that have systematically evaluated the efficacy of products containing tea tree oil for treating acne (Table 1). Of these, six [15], [16], [17], [18], [20], [21] were comparative, of which three [16], [17], [21] were double-blinded, with an additional study investigator-blinded [15]. Six studies have been published in full (five in English) and the remaining study was published as an abstract only
Properties of tea tree oil contributing to clinical efficacy
Major modes of action shown for conventional acne therapies include antimicrobial action (benzoyl peroxide and antibiotics), anti-inflammatory activity (retinoids), normalisation of follicular keratinisation (retinoids), reduction in the secretion of sebum (retinoids) and keratolytic activity (salicylic acid). Of these, only the first two properties have been demonstrated thus far for tea tree oil.
The antibacterial activity of tea tree oil against a range of clinically important bacteria is
Conclusions
Several studies have shown that application of tea tree oil products reduces the number of lesions in those with mild-to-moderate acne. Comparative trials showed that tea tree oil products were better than placebo and were equivalent to comparators including 5% benzoyl peroxide and 2% topical erythromycin. Adverse events were typical of those experienced with other topical treatments and occurred at similar rates. Efficacy may be attributed to the antibacterial and anti-inflammatory activity of
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