On The Shelf
Mickie Cathers
Tea tree oil is a popular and widely available essential oil touted for its benefits in supporting skin health and targeting certain bacteria. This essential oil is increasingly found in shampoos, soaps, and mouthwashes, as well as OTC treatments for cold sores, acne, burns, bites, lice, and fungal nail infections.
Background
Tea tree oil originates from the leaves of the Melaleuca alternifolia plant native to Australia. Tea tree oil has a long history as a traditional medicine used by the aboriginal people of Australia to treat wounds, burns, and insect bites. The oil is extracted from the leaves through steam distillation and contains over 100 components. The primary active component is terpinin-4-ol, comprising 35% to 48% of tea tree oil.
As research has shown that terpinin-4-ol can destroy certain bacteria, viruses, and fungi, these germ-fighting properties led to the idea that tea tree oil may be a natural remedy to treat bacterial and fungal skin conditions, prevent infection, and promote healing.
Is there a benefit?
Studies have explored how tea tree oil may aid acne, athlete’s foot, and nail fungus, show beneficial antimicrobial effects against bacteria, fungi, viruses, and mites, and enhance the healing process of wounds. Several studies suggest tea tree oil can destroy common bacteria and viruses, including E. coli, S. pneumoniae, and H. influenzae. However, most studies on anti-inflammatory or antifungal properties are in vitro or animal studies, with few human trials available.
Tea tree oil may be an optional antiseptic for minor cuts and scrapes by targeting Staphylococcus aureus and other bacteria that can cause infection in open wounds. Authors of an October 19, 2023, in vitro study published in Pharmaceutics assessed the efficacy of tea tree oil against bacterial strains isolated from eye infections. They focused on tea tree oil’s ability to inhibit biofilm formation. Their findings revealed that tea tree oil exhibited a substantial reduction in biofilm biomass, ranging from 30% to 70% and resulted in notable demonstrated efficacy against bacterial strains such as Corynebacterium spp. and Staphylococcus spp. (including Staphylococcus aureus), as well as a reference strain of Staphylococcus aureus.
Kairey and colleagues published a systematic review of randomized controlled trials on March 24, 2023, in Frontiers in Pharmacology analyzing the efficacy and safety of tea tree oil for human health. Forty-six articles from the fields of dentistry, dermatology, infectious disease, ophthalmology, and podiatry, as well as anxiety and sleep quality, were assessed and summarized.
Results indicated that oral mouthwashes with 0.2% to 0.5% tea tree oil may limit accumulation of dental plaque. Gels containing 5% tea tree oil applied directly to the periodontium may aid treatment of periodontitis as an adjunctive therapy to scaling and root planing. Topical tea tree oil regimens showed similar efficacy to standard treatments for decolonizing the body from MRSA. The authors called for more evidence to confirm the benefits of tea tree oil for reducing acne lesions and severity and local anti-inflammatory effects on skin as well as efficacy of tea tree oil–based eyelid wipes for Demodex mite control. They noted that the quality of research overall was poor to modest and higher quality trials with larger sample sizes and better reporting were required to substantiate potential therapeutic applications of tea tree oil. Kairey and colleagues also pointed out that no trials were identified that studied the well-established traditional uses of tea tree oil for the treatment of minor wounds, boils, and insect bites.
Dosage and availability
Tea tree oil is available over the counter or online in common cosmetic products such as shampoos, massage oils, and skin creams, and available as 100% undiluted or diluted forms ranging from 5% to 50% strength. There are no recommended dosages, but ranges include 5% to 10% gel/cream topically per day.
What to tell your patients
While tea tree oil is generally considered safe for topical use, adverse reactions can occur in some patients. Alert patients that even concentrations of 5% to 10% can cause contact sensitization and allergic contact dermatitis reactions. Testing a few drops on a small area of skin and waiting 24 hours to see if any reaction occurs would be a wise precaution. Caution patients not to ingest tea tree oil as it may be toxic if swallowed. ■