Tea tree oil
Overview
Tea tree oil, or melaleuca oil, is a pale yellow colour to nearly clear essential oil
Essential oil
An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. Essential oils are also known as volatile oils, ethereal oils or aetherolea, or simply as the "oil of" the plant from which they were extracted, such as oil of clove...

 with a fresh camphor
Camphor
Camphor is a waxy, white or transparent solid with a strong, aromatic odor. It is a terpenoid with the chemical formula C10H16O. It is found in wood of the camphor laurel , a large evergreen tree found in Asia and also of Dryobalanops aromatica, a giant of the Bornean forests...

aceous odor
Odor
An odor or odour is caused by one or more volatilized chemical compounds, generally at a very low concentration, that humans or other animals perceive by the sense of olfaction. Odors are also commonly called scents, which can refer to both pleasant and unpleasant odors...

. It is taken from the leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....

 of the Melaleuca alternifolia
Melaleuca alternifolia
Melaleuca alternifolia, commonly known as Narrow-leaved Paperbark, Narrow-leaved Tea-tree, Narrow-leaved Ti-tree, or Snow-in-summer, is a species of tree or tall shrub in the plant genus Melaleuca. Native to Australia, it occurs on the north coast and adjacent ranges of New South Wales...

, which is native to the northeast coast of New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. Tea tree oil should not be confused with tea oil
Tea oil
Tea seed oil is an edible, pale amber-green fixed oil with a sweet, herbal aroma. It is cold-pressed mainly from the seeds of Camellia oleifera but also from Camellia sinensis or Camellia japonica....

, the sweet seasoning and cooking oil from pressed seeds of the tea plant Camellia sinensis
Camellia sinensis
Camellia sinensis is the species of plant whose leaves and leaf buds are used to produce Chinese tea. It is of the genus Camellia , a genus of flowering plants in the family Theaceae. White tea, green tea, oolong, pu-erh tea and black tea are all harvested from this species, but are processed...

(beverage tea
Tea
Tea is an aromatic beverage prepared by adding cured leaves of the Camellia sinensis plant to hot water. The term also refers to the plant itself. After water, tea is the most widely consumed beverage in the world...

), or the tea oil plant Camellia oleifera
Camellia oleifera
Camellia oleifera, which originated in China, is notable as an important source of edible oil obtained from its seeds...

.
The indigenous
Indigenous Australians
Indigenous Australians are the original inhabitants of the Australian continent and nearby islands. The Aboriginal Indigenous Australians migrated from the Indian continent around 75,000 to 100,000 years ago....

 Bundjalung people of eastern Australia use “tea trees” as a traditional medicine
Traditional medicine
Traditional medicine comprises unscientific knowledge systems that developed over generations within various societies before the era of modern medicine...

 by inhaling the oils from the crushed leaves to treat coughs and colds.
Encyclopedia
Tea tree oil, or melaleuca oil, is a pale yellow colour to nearly clear essential oil
Essential oil
An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. Essential oils are also known as volatile oils, ethereal oils or aetherolea, or simply as the "oil of" the plant from which they were extracted, such as oil of clove...

 with a fresh camphor
Camphor
Camphor is a waxy, white or transparent solid with a strong, aromatic odor. It is a terpenoid with the chemical formula C10H16O. It is found in wood of the camphor laurel , a large evergreen tree found in Asia and also of Dryobalanops aromatica, a giant of the Bornean forests...

aceous odor
Odor
An odor or odour is caused by one or more volatilized chemical compounds, generally at a very low concentration, that humans or other animals perceive by the sense of olfaction. Odors are also commonly called scents, which can refer to both pleasant and unpleasant odors...

. It is taken from the leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....

 of the Melaleuca alternifolia
Melaleuca alternifolia
Melaleuca alternifolia, commonly known as Narrow-leaved Paperbark, Narrow-leaved Tea-tree, Narrow-leaved Ti-tree, or Snow-in-summer, is a species of tree or tall shrub in the plant genus Melaleuca. Native to Australia, it occurs on the north coast and adjacent ranges of New South Wales...

, which is native to the northeast coast of New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. Tea tree oil should not be confused with tea oil
Tea oil
Tea seed oil is an edible, pale amber-green fixed oil with a sweet, herbal aroma. It is cold-pressed mainly from the seeds of Camellia oleifera but also from Camellia sinensis or Camellia japonica....

, the sweet seasoning and cooking oil from pressed seeds of the tea plant Camellia sinensis
Camellia sinensis
Camellia sinensis is the species of plant whose leaves and leaf buds are used to produce Chinese tea. It is of the genus Camellia , a genus of flowering plants in the family Theaceae. White tea, green tea, oolong, pu-erh tea and black tea are all harvested from this species, but are processed...

(beverage tea
Tea
Tea is an aromatic beverage prepared by adding cured leaves of the Camellia sinensis plant to hot water. The term also refers to the plant itself. After water, tea is the most widely consumed beverage in the world...

), or the tea oil plant Camellia oleifera
Camellia oleifera
Camellia oleifera, which originated in China, is notable as an important source of edible oil obtained from its seeds...

.

History and extraction

The indigenous
Indigenous Australians
Indigenous Australians are the original inhabitants of the Australian continent and nearby islands. The Aboriginal Indigenous Australians migrated from the Indian continent around 75,000 to 100,000 years ago....

 Bundjalung people of eastern Australia use “tea trees” as a traditional medicine
Traditional medicine
Traditional medicine comprises unscientific knowledge systems that developed over generations within various societies before the era of modern medicine...

 by inhaling the oils from the crushed leaves to treat coughs and colds. They also sprinkle leaves on wounds, after which a poultice
Poultice
A poultice, also called cataplasm, is a soft moist mass, often heated and medicated, that is spread on cloth over the skin to treat an aching, inflamed, or painful part of the body. It can be used on wounds such as cuts...

 is applied. In addition, tea tree leaves are soaked to make an infusion
Infusion
An infusion is the outcome of steeping plants with desired chemical compounds or flavors in water or oil.-History:The first recorded use of essential oils was in the 10th or 11th century by the Persian polymath Avicenna, possibly in The Canon of Medicine.-Preparation techniques:An infusion is very...

 to treat sore throats or skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

 ailments.

Use of the oil itself, as opposed to the unextracted plant material, did not become common practice until researcher Arthur Penfold published the first reports of its antimicrobial
Antimicrobial
An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...

 activity in a series of papers in the 1920s and 1930s. In evaluating the antimicrobial activity of M. alternifolia, tea tree oil was rated as 11 times more active than phenol
Phenol
Phenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...

.

The commercial tea tree oil industry
Industry
Industry refers to the production of an economic good or service within an economy.-Industrial sectors:There are four key industrial economic sectors: the primary sector, largely raw material extraction industries such as mining and farming; the secondary sector, involving refining, construction,...

 was born after the medicinal properties of the oil were first reported by Penfold in the 1920s. It was produced from natural bush stands of M. alternifolia that produced oil with the appropriate chemotype
Chemotype
Introduced by Pierre Franchomme in 1975 and formalized in the European Union in 2006 with the adoption of the regulation REACH, a chemotype is a chemically distinct entity in a plant or microorganism, with differences in the composition of the secondary metabolites...

. The plant material was hand cut and often distilled on the spot in makeshift, mobile, wood-fired bush still
Still
A still is a permanent apparatus used to distill miscible or immiscible liquid mixtures by heating to selectively boil and then cooling to condense the vapor...

s.

Production ebbed after World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, as demand for the oil declined, presumably due to the development of effective antibiotics and the waning image of natural products. Interest in the oil was rekindled in the 1970s as part of the general renaissance of interest in natural products. Commercial plantations were established in the 1970s and 1980s, which led to mechanization
Mechanization
Mechanization or mechanisation is providing human operators with machinery that assists them with the muscular requirements of work or displaces muscular work. In some fields, mechanization includes the use of hand tools...

 and large-scale production of a consistent essential oil product.

Among over 98 compounds
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 contained in the oil, terpinen-4-ol
Terpinen-4-ol
Terpinen-4-ol is a terpene with a molecular weight of 154.249.It is considered the primary active ingredient of tea tree oil. It is also the compound of highest concentration in the essential oil of nutmeg.-Additional images:...

 is responsible for most of the antimicrobial activity.

Although tea tree oil normally is extracted from Melaleuca alternifolia
Melaleuca alternifolia
Melaleuca alternifolia, commonly known as Narrow-leaved Paperbark, Narrow-leaved Tea-tree, Narrow-leaved Ti-tree, or Snow-in-summer, is a species of tree or tall shrub in the plant genus Melaleuca. Native to Australia, it occurs on the north coast and adjacent ranges of New South Wales...

commercially, it can also be extracted from Melaleuca dissitiflora
Melaleuca dissitiflora
Melaleuca dissitiflora, commonly known as creek tea–tree, is a shrub of the Melaleuca genus native to Australia.-Growth:The plant has a height of , a width of , and grows at a medium to fast rate. The species occurs in Western Australia, South Australia, the Northern Territory and...

and Melaleuca linariifolia
Melaleuca linariifolia
Melaleuca linariifolia, popularly known as Snow-in-Summer, is a plant native to eastern Australia. Other names include Narrow-leaved Paperbark, Flax-leaved Paperbark and the Gadigal Budjur....

.
Tea tree oil is defined by international standard ISO
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...

 4730 (2004) ("Oil of Melaleuca, Terpinen-4-ol type"), which specifies levels of 15 components which are needed to define the oil as "tea tree oil."

Composition

Tea tree oil ISO 4730 (2004) Concentration [%]
terpinen-4-ol
Terpinen-4-ol
Terpinen-4-ol is a terpene with a molecular weight of 154.249.It is considered the primary active ingredient of tea tree oil. It is also the compound of highest concentration in the essential oil of nutmeg.-Additional images:...

 
30-48
γ-terpinene
Terpinene
The terpinenes are three isomeric hydrocarbons that are classified as terpenes. They each have the same molecular formula and carbon framework, but they differ in the position of carbon-carbon double bonds. α-Terpinene has been isolated from cardamom and marjoram oils, and from other natural...

 
10–28
α-terpinene  5–13
1,8-Cineole  0–15
α-terpinolene  1.5–5
α-terpineol  1.5–8
α-pinene  1–6
p-cymene  0.5–8


Tea tree oil has been scientifically investigated only recently. Some sources suggest beneficial medical
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

 properties when applied topical
Topical
In medicine, a topical medication is applied to body surfaces such as the skin or mucous membranes such as the vagina, anus, throat, eyes and ears.Many topical medications are epicutaneous, meaning that they are applied directly to the skin...

ly, including antiviral
Antiviral
Antiviral may refer to:*Antiviral drug*Antiviral protein*Antivirus software*Antiviral Therapy, an academic journal...

, antibacterial, antifungal
Fungicide
Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...

, and antiseptic
Antiseptic
Antiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction...

 qualities. It also has beneficial cosmetic
Cosmetics
Cosmetics are substances used to enhance the appearance or odor of the human body. Cosmetics include skin-care creams, lotions, powders, perfumes, lipsticks, fingernail and toe nail polish, eye and facial makeup, towelettes, permanent waves, colored contact lenses, hair colors, hair sprays and...

 properties.

Tea tree oil is active against Staphylococcus aureus
Staphylococcus aureus
Staphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...

, including MRSA. Tea tree oil is less successful for application in the nose. Also, there is clinical evidence that topical dermatological preparations containing tea tree oil may be more effective than conventional antibiotics in preventing transmission of CA-MRSA.

Recent studies support a role for the topical
Topical
In medicine, a topical medication is applied to body surfaces such as the skin or mucous membranes such as the vagina, anus, throat, eyes and ears.Many topical medications are epicutaneous, meaning that they are applied directly to the skin...

 application of tea tree oil in skin care
Human skin
The human skin is the outer covering of the body. In humans, it is the largest organ of the integumentary system. The skin has multiple layers of ectodermal tissue and guards the underlying muscles, bones, ligaments and internal organs. Human skin is similar to that of most other mammals,...

 and for the treatment of various disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...

s and conditions. Tea tree oil appears to be effective against bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

, virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

es, fungal infections
Mycosis
A mycosis is a fungal infection of animals, including humans. Mycoses are common, and a variety of environmental and physiological conditions can contribute to the development of fungal diseases...

, mite
Mite
Mites, along with ticks, are small arthropods belonging to the subclass Acari and the class Arachnida. The scientific discipline devoted to the study of ticks and mites is called acarology.-Diversity and systematics:...

s such as scabies
Scabies
Scabies , known colloquially as the seven-year itch, is a contagious skin infection that occurs among humans and other animals. It is caused by a tiny and usually not directly visible parasite, the mite Sarcoptes scabiei, which burrows under the host's skin, causing intense allergic itching...

, and lice such as head lice
Head louse
The head louse is an obligate ectoparasite of humans. Head lice are wingless insects spending their entire life on human scalp and feeding exclusively on human blood...

. A 2008 study of in vitro toxicity showed a tea tree oil preparation was more effective against head lice than permethrin, a popular pharmaceutical remedy.

In the treatment of moderate common acne
Acne vulgaris
Acne vulgaris is a common human skin disease, characterized by areas of skin with seborrhea , comedones , papules , pustules , Nodules and possibly scarring...

, topical application of 5% tea tree oil has shown an effect comparable to 5% benzoyl peroxide
Benzoyl peroxide
Benzoyl peroxide is an organic compound in the peroxide family. It consists of two benzoyl groups bridged by a peroxide link. Its structural formula is [C6H5C]2O2. It is one of the most important organic peroxides in terms of applications and the scale of its production...

, albeit with slower onset of action.

Tea tree oil is a known antifungal agent, effective in vitro
In vitro
In vitro refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments...

against multiple dermatophyte
Dermatophyte
Dermatophytes are a common label for a group of three types of fungus that commonly causes skin disease in animals and humans. These anamorphic genera are: Microsporum, Epidermophyton and Trichophyton. There are about 40 species in these three genera...

s found on the skin. In vivo
In vivo
In vivo is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...

, shampoo
Shampoo
Shampoo is a hair care product used for the removal of oils, dirt, skin particles, dandruff, environmental pollutants and other contaminant particles that gradually build up in hair...

 with 5% tea tree oil has been shown to be an effective treatment for dandruff
Dandruff
Dandruff is the shedding of dead skin cells from the scalp . Dandruff is sometimes caused by frequent exposure to extreme heat and cold. As it is normal for skin cells to die and flake off, a small amount of flaking is normal and common; about 487,000 cells/cm2 get released normally after...

 due to its ability to treat Malassezia furfur
Malassezia furfur
Malassezia is a genus of fungi. Malassezia is naturally found on the skin surfaces of many animals, including humans. In occasional opportunistic infections,...

, the most common cause of the condition.

One clinical study found that 100% tea tree oil administered topically, combined with debridement, was comparable to clotrimazole in effectiveness against onychomycosis, the most frequent cause of nail disease.

The effectiveness of topical tea tree oil preparations for the treatment of the yeast infection Candidiasis
Candidiasis
Thrush redirects here. For the hoof infection see Thrush .Candidiasis or thrush is a fungal infection of any of the Candida species , of which Candida albicans is the most common...

 is supported by its ability to kill Candida
Candida (genus)
Candida is a genus of yeasts. Many species are harmless commensals or endosymbionts of animal hosts including humans, but other species, or harmless species in the wrong location, can cause disease. Candida albicans can cause infections in humans and other animals, especially in immunocompromised...

 in vitro.

There is some very limited research that has shown that tea tree oil may have topical antiviral
Antiviral
Antiviral may refer to:*Antiviral drug*Antiviral protein*Antivirus software*Antiviral Therapy, an academic journal...

 activity, especially against the herpes virus (cold sores), chicken pox, shingles blisters, etc.

One study has shown a 5% tea tree oil solution to be more effective than commercial medications against the scabies mite in an in vitro
In vitro
In vitro refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments...

 situation.

In aquarium fish

Diluted solutions of tea tree oil are often used as a remedy to treat bacterial and fungal infections in aquarium fish
Aquarium fish
In fishkeeping, species of aquarium fish vary with the water chemistry of the aquarium.For species of fish found in particular types of aquaria, see:*List of brackish aquarium fish species*List of freshwater aquarium amphibian species...

. Common brand names are Melafix
Melafix
Melafix is an all-natural aquarium antibiotic consisting of tea tree oil. It is a wide-range antibiotic product, and thus is effective for a wide variety of bacterial and fungal infections, such as fin rot and body "fungus"...

 and Bettafix. Melafix is a stronger concentration and Bettafix is a lower concentration that makes it harder to overdose smaller fish, especially betta
Betta
Betta is a large genus of small, often colorful, freshwater ray-finned fishes in the gourami family . The type species is B. picta, the spotted betta.By far the best known Betta species, however, is B...

s. It is most commonly used to promote fin
Fin
A fin is a surface used for stability and/or to produce lift and thrust or to steer while traveling in water, air, or other fluid media, . The first use of the word was for the limbs of fish, but has been extended to include other animal limbs and man-made devices...

 and tissue regrowth, but is also effective in treating other conditions, such as fin rot
Fin rot
Fin rot is a symptom of disease or the actual disease in fish. This is a disease which is most often observed in aquaria and aquaculture, but can also occur in natural populations....

 or velvet
Velvet (fish disease)
Velvet disease, also called gold dust disease is a fish disease caused by the dinoflagellate parasites of the genus Piscinoodinium, which gives the fish a dusty, slimy look. The disease occurs most commonly in tropical and marine aquaria.-Life cycle:The single-celled parasite's life cycle can be...

. The remedy is used mostly on betta fish, but can also be used with other aquarium fish, other than goldfish.

Safety

According to the American Cancer Society: "Tea tree oil is toxic when swallowed. It has been reported to cause drowsiness, confusion, hallucinations, coma, unsteadiness, weakness, vomiting, diarrhea, stomach upset, blood cell abnormalities, and severe rashes. It should be kept away from pets and children."

A small number of people experience allergic contact dermatitis as a reaction to dermal contact with tea tree oil. In an Italian study of 725 consecutive patients, patients were patch tested with undiluted, 1%, and 0.1% tea tree oil. For undiluted tea tree oil, nearly 6% of the patients observed positive reactions of skin irritation. Only 1 of 725 patients observed a positive reaction of skin irritation with the 1% dilution. None of the 725 patients observed adverse reactions with the 0.1% dilution. Allergic reactions may be due to the various oxidation products that are formed by exposure of the oil to light and/or air.

External application of tea tree oil undiluted and/or at inappropriate high doses has been associated with toxicity, including death, in cats and other animals, due to ingestion during grooming.

A highly disputed case study reported in The New England Journal of Medicine concluded that repeated topical exposure of lavender and tea tree oils may have caused prepubertal gynecomastia
Gynecomastia
Gynecomastia or Gynaecomastia, , is the abnormal development of large mammary glands in males resulting in breast enlargement. The term comes from the Greek γυνή gyné meaning "woman" and μαστός mastós meaning "breast"...

 in three young boys. The study involved just three individuals and found lavender
Lavender
The lavenders are a genus of 39 species of flowering plants in the mint family, Lamiaceae. An Old World genus, distributed from Macaronesia across Africa, the Mediterranean, South-West Asia, Arabia, Western Iran and South-East India...

 to be the only common ingredient used by the boys in the study. While all three cases involved the use of products containing lavender oil
Lavender oil
Lavender oil is an essential oil obtained by distillation from the flower spikes of certain species of lavender. Two forms 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...

 as an ingredient, only one boy also used products containing tea tree oil. In all cases, the prepubertal gynecomastia reversed after several months. Researchers have noted that estrogenic or antiandrogenic activities have also been reported for some other commonly used essential oils, as well as some foods such as almonds and peanuts. [reference to peanuts and almonds is not relevant to citation] Others have cast doubt on the conclusions of the article and dismissed the study as having used "poor methodology". The research has been most criticized for making medically related conclusions about tea tree oil based on a single individual, while outside factors were more likely to have caused the condition. Critics of the study note that millions of people use products containing tea tree oil on a regular basis and there has never been another documented relation of tea tree oil and gynecomastia before or after this study was published.

If used in concentrations below 4% or particularly below 0.25%, tea tree oil may fail to kill bacteria and create selection pressure, which may result in them becoming less sensitive to tea tree oil and even some antibiotics in vitro.

Undiluted tea tree oil can cause some hearing loss when used in the ears of animals; however, a 2% concentration has not been shown to have any lasting effect. It is not known whether the same is true for humans.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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