Tea tree oil
Tea tree oil is the essential oil distilled from the leaves of Melaleuca alternifolia, a tree native to New South Wales, Australia. It is one of the most studied botanical oils in skincare, and it is also a known skin sensitizer, especially once it has oxidized.
At a glance
- Evidence level A. Published research on the ingredient itself.
- What it is. A steam-distilled essential oil, dominated by the compound terpinen-4-ol.
- What the literature covers. Laboratory studies of activity against microbes, and a small number of clinical trials.
- Caution. Can cause allergic skin reactions, more so when old or oxidized. Patch test first.
What it is
Tea tree oil is a mixture of around a hundred compounds, mostly terpenes. Its quality is defined by an international standard, ISO 4730, which sets the ranges for its main components. Terpinen-4-ol is the largest and the one most associated with its activity in the literature.
As an essential oil, it contributes scent to any formula that contains it. A product listing tea tree oil is therefore a scented product, even if no "parfum" appears on its label.
On an ingredient list it appears under its INCI name, Melaleuca Alternifolia (Tea Tree) Leaf Oil: the Latin genus and species, the common name in brackets, then the plant part and the form.
What it does in skincare
Tea tree oil is added to skincare for its scent, for its botanical character, and because of its long history of use in Australian folk practice. What it does on skin depends on the concentration, the rest of the formula and the condition of the oil. It oxidizes on contact with air and light, and its oxidation products are more likely to sensitize skin than fresh oil.
That profile makes it one of the ingredients most often asked about by people with reactive skin. See fragrance allergens for how scent-bearing ingredients are labeled.
Evidence
The studies below describe the ingredient itself.
Carson, Hammer and Riley reviewed the activity of tea tree oil against microbes and its other reported properties in 2006. Most of that evidence comes from laboratory studies.
Two small clinical trials in people with acne are often cited. Bassett and colleagues compared a tea tree oil gel with a benzoyl peroxide lotion in 1990. Enshaieh and colleagues compared a tea tree oil gel with a placebo gel in 2007. Both were short and used gels far stronger than a cosmetic serum carries; each result belongs to the gel under study.
On safety, Hammer and colleagues reviewed the toxicity of tea tree oil in 2006. Hausen and colleagues showed in 1999 that degradation products formed as the oil ages are the main sensitizing agents. The EU Scientific Committee on Consumer Products issued an opinion on tea tree oil in 2008 that addressed its sensitizing potential and oxidation.
Tea tree oil is a recognized sensitizer, whatever its plant origin. More on the belief that plant oils are gentler: the "natural is gentler" myth.
Use and caution
- Patch test any product containing tea tree oil before using it on the face. See patch testing and declared allergens.
- Never apply undiluted essential oil to skin.
- Keep products containing it closed, cool and away from light, and discard them once the scent or color changes.
- Stop at the first sign of itching, redness or rash that persists.
- If your skin reacts easily, read sensitivity and recovery first.
In Vegalab products
The Clarifying NanoSerum sealed vial set lists Melaleuca Alternifolia (Tea Tree) Leaf Oil as the last ingredient in its declaration, after rosemary leaf extract. It is not a fragrance-free formula.
What the last position in a list means: how to read an ingredient list.
Related ingredients
References
- Carson CF, Hammer KA, Riley TV. Melaleuca alternifolia (tea tree) oil: a review of antimicrobial and other medicinal properties. Clin Microbiol Rev. 2006;19(1):50-62.
- Bassett IB, Pannowitz DL, Barnetson RS. A comparative study of tea-tree oil versus benzoylperoxide in the treatment of acne. Med J Aust. 1990;153(8):455-458.
- Enshaieh S, Jooya A, Siadat AH, Iraji F. The efficacy of 5% topical tea tree oil gel in mild to moderate acne vulgaris: a randomized, double-blind placebo-controlled study. Indian J Dermatol Venereol Leprol. 2007;73(1):22-25.
- Hammer KA, Carson CF, Riley TV, Nielsen JB. A review of the toxicity of Melaleuca alternifolia (tea tree) oil. Food Chem Toxicol. 2006;44(5):616-625.
- Hausen BM, Reichling J, Harkenthal M. Degradation products of monoterpenes are the sensitizing agents in tea tree oil. Am J Contact Dermat. 1999;10(2):68-77.
- Scientific Committee on Consumer Products (SCCP). Opinion on tea tree oil. SCCP/1155/08. European Commission; 2008.
- International Organization for Standardization. ISO 4730:2017, Essential oil of Melaleuca, terpinen-4-ol type (Tea Tree oil).
Frequently asked questions
Is tea tree oil safe on skin?
Tea tree oil is widely used, and it is also a recognized skin sensitizer, especially once it has oxidized. Never apply it undiluted, and patch test any product containing it.
Does tea tree oil count as fragrance?
It is an essential oil, so it contributes scent and scent-related allergens of its own. A product containing it is a scented product, even if "Parfum" is absent from the list.
Why does old tea tree oil cause more reactions?
Oxidation on exposure to air and light forms degradation products that are more likely to sensitize skin than fresh oil. Keep products containing it closed, cool and away from light.
Last updated: