Tea tree oil

# Overview
Tea tree oil is an extraction from the Melaleuca tree. Tea tree oil should not be confused with tea oil, the sweet seasoning and cooking oil from pressed seeds of the tea plant (drinking tea) Camellia sinensis or the tea oil plant Camellia oleifera.
The term "tea tree oil" is also somewhat of a misnomer since Melaleuca alternifolia is a paperbark rather than a tea tree (genus Leptospermum).
Tea tree oil or melaleuca oil is a clear to very pale golden color essential oil with a fresh camphoraceous odour. It is taken from the leaves of the Melaleuca alternifolia which is native to the northeast coast of New South Wales, Australia. The oil is believed to have beneficial cosmetic and medical properties (including antiseptic and antifungal action).

# History and extraction
The indigenous Bundjalung people of eastern Australia use tea trees as a traditional medicine by inhaling the oils from the crushed leaves to treat coughs and colds. They also sprinkle leaves on wounds, after which a poultice is applied. In addition, tea tree leaves are soaked to make an infusion to treat sore throats or skin 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 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.
The commercial tea tree oil industry 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. The plant material was hand cut and often distilled on the spot in makeshift, mobile, wood-fired bush stills.
Production ebbed after World War II 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 lead to mechanization and large-scale production of a consistent essential oil product.
Among over 98 compounds contained in the oil, terpinen-4-ol is responsible for most of the antimicrobial actions.
Although tea tree oil is normally extracted from Melaleuca alternifolia commercially, it can also be extracted from Melaleuca dissitiflora and Melaleuca linariifolia. Tea tree oil is defined by international standard ISO 4730 ("Oil of Melaleuca, Terpinen-4-ol type"), which specifies levels of 14 components which are needed to define the oil as "tea tree oil."

# Medicinal use
Tea tree oil has been recognized as a potent antiseptic in Australia anecdotally for much longer than there has been scientific evidence. However, recent studies support a role for tea tree oil in skin care and treatment of various ailments.
Tea tree oil is a known antifungal agent, effective in vitro against multiple dermatophytes found on the skin. In vivo, shampoo with 5% tea tree oil has been shown to be an effective treatment for dandruff due to its ability to treat Malassezia furfur, the most common cause of the condition.
Tea Tree Oil is used in medically used cosmetic products also. Some references are there to suggest its role as antiviral.
Effectiveness of topical tea tree oil preparations for Candidiasis is supported by their ability to kill Candida in vitro.
In the treatment of moderate acne, topical application of 5% tea tree oil has shown an effect comparable to 5% benzoyl peroxide, albeit with slower onset of action. Another study in 2007 5% strength gel was compared against a placebo, with statistically significant results.
Tea tree oil is also effective for treating insect bites, boils and minor wounds. It has also been known to help soothe sunburns, poison ivy, ear infections, and bee stings.
Diluted solutions of tea tree oil are sold as remedies which claim to treat bacterial and fungal infection in pet fish.
Pets: Skin problems, wounds, insect bites and stings, and ringworm can all be treated with tea tree oil or products made with tea tree oil. There are some cases where pure tea tree oil placed on the skin of the animal can cause irritation (recovering quickly after discontinuing). Therefore, test the treatment first by applying only to a small area of the animal's skin.
Toothpastes and mouthwashes containing tea tree oil are shown to be effective for a number of oral problems. Some of these include, halitosis (bad breath), gum disease, and canker sores.
There is some limited research that has shown that tea tree oil may have anti-viral activity, especially with the Herpes virus (cold sores, chicken pox and shingles blisters, warts, etc.)

# Safety
Melaleuca oil is used almost exclusively externally.
Data on oral use of tea tree oil in humans in large quantities is sparse aside from several anecdotal reports of side effects following oral ingestion. Symptoms may include ataxia and drowsiness. A relatively small number of people report an allergic reaction to tea tree oil which could consist of a minor skin irritation. In a study of 725 consecutive patients, patients were patch tested with undiluted, 1% and
0.1% Tea Tree Oil. For pure undiluted tea tree oil, less than 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.
A case study reported in a recent publication showed a possible association between repeated topical application of products containing lavender oil with prepubertal gynecomastia (abnormal breast development in young boys). The study involved just three individuals. All three cases included the use of lavender oil. In one of the three cases, a product was used that contained lavender oil as well as tea tree oil, and other ingredients. The prepubertal gynecomastia reversed after discontinuing use of products containing lavender oil. In the same paper, results from cell culture assays indicated that both essential oils exhibit weak estrogenic properties. Researchers indicated that other components in these products may also have contributed to the gynecomastia, but those components were not yet tested. Researchers also noted that estrogenic activities have also been reported for many other commonly used essential oils as well as foods such as almonds and peanuts. Other articles have cast doubt as to the conclusions of the article and dismissed the study as having used "poor methodology".
As with many antibiotics, if used in 4% concentrations or below it may activate stress reactions in bacteria which can cause them to become less sensitive to antibiotics in vitro. Tea tree oil is not recommended for use in the ears.