Tea tree oil, also known as melaleuca oil, is an essential oil with a fresh, camphoraceous odor and a colour that ranges from pale yellow to nearly colourless and clear. [1] [2] It is derived from the leaves of the tea tree, Melaleuca alternifolia , native to southeast Queensland and the northeast coast of New South Wales, Australia. The oil comprises many constituent chemicals, and its composition changes if it is exposed to air and oxidizes. Commercial use of tea tree oil began in the 1920s, pioneered by the entrepreneur Arthur Penfold.
As a traditional medicine, it is typically used as a topical medication in low concentrations for the treatment of skin conditions, but little evidence exists of clinical efficacy. [2] [3] [4] [5]
Tea tree oil is neither a patented product nor an approved drug in the United States, [2] [5] although it is approved as a complementary medicine for aromatherapy in Australia. [6] It is poisonous if consumed by mouth and is unsafe for children. [7]
Although tea tree oil is claimed to be useful for treating dandruff, acne, lice, herpes, insect bites, scabies, and skin fungal or bacterial infections, [5] [8] insufficient evidence exists to support any of these claims due to the limited quality of research. [2] [4] [9] A 2015 Cochrane review of acne complementary therapies found a single low-quality trial showing benefit on skin lesions compared to placebo. [10]
According to the Committee on Herbal Medicinal Products (CHMP) of the European Medicines Agency, traditional usage suggests that tea tree oil is a possible treatment for "small, superficial wounds, insect bites, and small boils" and that it may reduce itching in minor cases of athlete's foot. The CHMP states that tea tree oil products should not be used on people under 12 years of age. [11]
Tea tree oil is not recommended for treating nail fungus because it is yet to be proven effective, [12] It is not recommended for treating head lice in children because its effectiveness and safety have not been established and it could cause skin irritation or allergic reactions. [13] [14] There is no good evidence tea tree oil is an effective treatment for demodex mite infestations. [15]
Tea tree oil is highly toxic when ingested orally. [2] [4] [16] [9] It may cause drowsiness, confusion, hallucinations, coma, unsteadiness, weakness, vomiting, diarrhea, nausea, blood-cell abnormalities, and severe rashes. It should be kept away from pets and children. [9] It should not be used in or around the mouth. [2] [4] [7]
Application of tea tree oil to the skin can cause an allergic reaction, [2] the potential for which increases as the oil ages and its chemical composition changes. [17] Adverse effects include skin irritation, allergic contact dermatitis, systemic contact dermatitis, linear immunoglobulin A disease, erythema multiforme-like reactions, and systemic hypersensitivity reactions. [8] [18] Allergic reactions may be due to the various oxidation products that are formed by exposure of the oil to light and air. [18] [19] Consequently, oxidized tea tree oil should not be used. [20]
In Australia, tea tree oil is one of the many essential oils causing poisoning, mostly of children. From 2014 to 2018, 749 cases were reported in New South Wales, accounting for 17% of essential oil poisoning incidents. [21]
Tea tree oil potentially poses a risk for causing abnormal breast enlargement in men [22] [23] and prepubertal children. [24] [25] A 2018 study by the National Institute of Environmental Health Sciences found four of the constituent chemicals (eucalyptol, 4-terpineol, dipentene, and alpha-terpineol) are endocrine disruptors, raising concerns of potential environmental health impact from the oil. [26]
In dogs and cats, death [27] [28] or transient signs of toxicity (lasting two to three days), such as lethargy, weakness, incoordination, and muscle tremors, have been reported after external application at high doses. [29]
As a test of toxicity by oral intake, the median lethal dose (LD50) in rats is 1.9–2.4 ml/kg. [30]
Component | Concentration |
---|---|
terpinen-4-ol | 35.0–48.0% |
γ-terpinene | 14–28% |
α-terpinene | 6.0–12.0% |
1,8-cineole | traces–10.0% |
terpinolene | 1.5–5.0% |
α-terpineol | 2.0–5.0% |
α-pinene | 1.0–4.0% |
p-cymene | 0.5–8.0% |
sabinene | traces–3.5% |
limonene | 0.5–1.5% |
aromadendrene | 0.2–3.0% |
ledene | 0.1–3.0% |
globulol | traces–1.0% |
viridiflorol | traces–1.0% |
Tea tree oil is defined by the International Standard ISO 4730 ("Oil of Melaleuca, terpinen-4-ol type"), containing terpinen-4-ol, γ-terpinene, and α-terpinene as about 70% to 90% of whole oil, while p-cymene, terpinolene, α-terpineol, and α-pinene collectively account for some 15% of the oil (table). [1] [3] [5] The oil has been described as colorless to pale yellow [1] [2] having a fresh, camphor-like smell. [31]
Tea tree oil products contain various phytochemicals, among which terpinen-4-ol is the major component. [1] [2] [3] Adverse reactions diminish with lower eucalyptol content. [8]
The name "tea tree" is used for several plants, mostly from Australia and New Zealand, from the family Myrtaceae related to the myrtle. The use of the name probably originated from Captain James Cook's description of one of these shrubs that he used to make an infusion to drink in place of tea. [32]
The commercial tea tree oil industry originated in the 1920s when Australian chemist Arthur Penfold investigated the business potential of a number of native extracted oils; he reported that tea tree oil had promise, as it exhibited antiseptic properties. [30]
Tea tree oil was first extracted from Melaleuca alternifolia in Australia, and this species remains the most important commercially. In the 1970s and 1980s, commercial plantations began to produce large quantities of tea tree oil from M. alternifolia. Many of these plantations are located in New South Wales. [30] Since the 1970s and 80s, the industry has expanded to include several other species for their extracted oil: Melaleuca armillaris and Melaleuca styphelioides in Tunisia and Egypt; Melaleuca leucadendra in Egypt, Malaysia, and Vietnam; Melaleuca acuminata in Tunisia; Melaleuca ericifolia in Egypt; and Melaleuca quinquenervia in the United States (considered an invasive species in Florida [33] ).
Similar oils can also be produced by water distillation from Melaleuca linariifolia and Melaleuca dissitiflora . [34] Whereas the availability and nonproprietary nature of tea tree oil would make it – if proved effective – particularly well-suited to a disease such as scabies that affects poor people disproportionately, those same characteristics diminish corporate interest in its development and validation. [5]
Melaleuca is a genus of nearly 300 species of plants in the myrtle family, Myrtaceae, commonly known as paperbarks, honey-myrtles or tea-trees. They range in size from small shrubs that rarely grow to more than 16 m (52 ft) high, to trees up to 35 m (115 ft). Their flowers generally occur in groups, forming a "head" or "spike" resembling a brush used for cleaning bottles, containing up to 80 individual flowers.
An essential oil is a concentrated hydrophobic liquid containing volatile chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the oil of the plant from which they were extracted, such as oil of clove. An essential oil is essential in the sense that it contains the essence of the plant's fragrance—the characteristic fragrance of the plant from which it is derived. The term "essential" used here does not mean indispensable or usable by the human body, as with the terms essential amino acid or essential fatty acid, which are so called because they are nutritionally required by a living organism.
Lavender oil is an essential oil obtained by distillation from the flower spikes of certain species of lavender. There are over 400 types of lavender worldwide with different scents and qualities. Two forms of lavender oil are distinguished, lavender flower oil, a colorless oil, insoluble in water, having a density of 0.885 g/mL; and lavender spike oil, a distillate from the herb Lavandula latifolia, having a density of 0.905 g/mL. Like all essential oils, it is not a pure compound; it is a complex mixture of phytochemicals, including linalool and linalyl acetate.
Herbal medicine is the study of pharmacognosy and the use of medicinal plants, which are a basis of traditional medicine. With worldwide research into pharmacology, some herbal medicines have been translated into modern remedies, such as the anti-malarial group of drugs called artemisinin isolated from Artemisia annua, a herb that was known in Chinese medicine to treat fever. There is limited scientific evidence for the safety and efficacy of many plants used in 21st-century herbalism, which generally does not provide standards for purity or dosage. The scope of herbal medicine sometimes include fungal and bee products, as well as minerals, shells and certain animal parts.
An insect repellent is a substance applied to the skin, clothing, or other surfaces to discourage insects from landing or climbing on that surface. Insect repellents help prevent and control the outbreak of insect-borne diseases such as malaria, Lyme disease, dengue fever, bubonic plague, river blindness, and West Nile fever. Pest animals commonly serving as vectors for disease include insects such as flea, fly, and mosquito; and ticks (arachnids).
Natural skin care uses topical creams and lotions made of ingredients available in nature. Much of the recent literature reviews plant-derived ingredients, which may include herbs, roots, flowers and essential oils, but natural substances in skin care products include animal-derived products such as beeswax, and minerals. These substances may be combined with various carrier agents, preservatives, surfactants, humectants and emulsifiers.
Cajeput tree is a common name used for certain classification of tree that has a white spongy bark that is flexible and can easily flake off the trunk. The Cajeput tree is of the genus Melaleuca, native to Australia and is commonly known in North America as the tea tree. The name "Cajeput tree" is primarily used for the species M. cajuputi, M. leucadendra, M. linariifolia, M. viridiflora and M. quinquenervia. Other names for these trees are the paperbark tree, punk tree, or the white bottle brush tree. Similar subtropical trees from the eucalyptus family are evergreens with pointed leaves and white, red or green flowers.
Cajuput oil is a volatile oil obtained by distillation from the leaves of the myrtaceous trees Melaleuca leucadendra, Melaleuca cajuputi, and probably other Melaleuca species. The trees yielding the oil are found throughout Maritime Southeast Asia and over the hotter parts of the Australian continent. The majority of the oil is produced on the Indonesian island of Sulawesi. The name "cajeput" is derived from its Malay name, kayu putih or "white wood".
Backhousia citriodora is a flowering plant in the family Myrtaceae, genus Backhousia. It is endemic to subtropical rainforests of central and south-eastern Queensland, Australia, with a natural distribution from Mackay to Brisbane.
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Melaleuca alternifolia, commonly known as tea tree, is a species of tree or tall shrub in the myrtle family, Myrtaceae. Endemic to Australia, it occurs in southeast Queensland and the north coast and adjacent ranges of New South Wales where it grows along streams and on swampy flats, and is often the dominant species where it occurs.
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Terpinen-4-ol is an isomer of terpineol with the chemical formula C10H18O. A primary constituent of tea tree oil, it is obtained as an extract from the leaves, branches, and bark of Melaleuca alternifolia Cheel. Despite considerable basic and preliminary clinical research of terpinen-4-ol and tea tree oil, its biological properties and potential for clinical uses have not been established as of 2019. It may be a factor in the contact dermatitis of tea tree oil when used topically.
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Melaleuca dissitiflora, commonly known as creek tea–tree, is a plant in the myrtle family, Myrtaceae and is native to Australia. It occurs in the drier parts of Queensland, the Northern Territory, South Australia and Western Australia. It grows in places like sandy creek beds and rocky gorges but it may have potential as a more productive source of "tea tree" oil than the usual Melaleuca alternifolia. It is closely related and very similar to Melaleuca linophylla with its papery bark, narrow leaves and loose spikes of creamy-white flowers but its flowers are larger, the stamens are longer and there are more stamens per bundle than in that species.
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