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Want To Know More About Essential Oils Such As Tea Tree Oil?

A report on these issues was published in Acta Derm Vernereol 1999; 79: 1-2.  Scandanavian University Press.

The information published describes essential oils including tea tree oil as complex mixtures of over 100 hydrocarbons and terpenes.  Neurotoxic effects were noted with no known mechanism of action.  The conclusion was that for safety reasons, the promotion of commercially available essential oils as treatments for head lice should be discouraged until more data is available.

© Acta Derm Venereol 1999; 79:1-2


Monoterpenoids And Tetralin as Pediculocides

    The increasing resistance of head lice to established insecticides means that patients and parents are seeking alternative effective treatments (1). Essential oils, including tea tree oil and Biz Niz, ? are promoted as treatments for head lice by alternative medicine therapists. Tea tree oil is the essential oil steam distilled from the leaves and terminal branches of tea trees, in particular the Myrtle tree (Melalenca alternifolia) (2). It is a complex mixture of over 100 hydrocarbons and terpenes. Of the 15 compounds found in highest concentration, 12 are monoterpenoids. These include terpinen-4-ol (30%), 1,8 cineole (15%), p Cymene, ? pinene, ? terpineol and ? terpinene (3). ? terpineol is also an insipient ingredient in some standard insecticide containing louse treatment lotions which are felt to be more effective (4). A 1% copper oleate shampoo (which also contains tetralin) has been shown to be an effective treatment in 1 clinical trial (5).  We examined the potential loucicidal activity of tea tree oil, copper oleate, tetralin, terpinen-4-ol; ? terpinene, using in vitro exposure tests with freshly collected live adult head lice.


Neat tea tree oil, tetralin, terpinene, ? terpineol and terpinen-4-ol were diluted to 1% and 10% solutions in isopropanol. Copper oleate crystals were created by combining copper sulphate and potassium oleate according to Nelson & Pink (6) and, from this, 1% and 10% aqueous solutions were made. All products were obtained from Sigma-Aldrich Co., Ltd (Poole, Dorset, UK). Chemical-impregnated filter papers were 
made by dipping Whatman no. 1 cellulose filter papers, 5 cm in diameter, into the various solutions. The filter papers were dried an stored at 4 degrees C in the dark in air-tight containers and used within 24 h. Live adult head lice were collected off school children (aged 4-11 years) from 3 primary schools using a fine-toothed louse detector comb. Consent for collecting lice was obtained from the South & West research 
ethics committee, school head teachers and pupil's parents. Lice were pooled together to provide sufficient test numbers. The lice were stored in a portable incubator set at 30 degrees C and 70%; relative humidity (the optimum lice survival conditions) (7) and used in the in vitro test within 2 h of collection. The lice were exposed (10 per filter paper) to the various impregnated filter papers as well as unimpregnated filter papers 
and assessed after 2 h. Mortality was judged as the absence of all internal and external movement on tactile stimulation.


The results are shown in Table 1. Compared with controls, there was a significant mortality for all chemicals tested, except copper oleate (p<10 –8, Fischer's exact test.) 
Lice were either dead or seemingly unaffected, except for gamma terpinene exposed head lice, which showed hyperexitability, increased abdominal contractions and uncoordinated movements at 1% exposure.

Table I. Mortality of head lice on exposure to potential insecticides

Insecticide Dead Alive
Tea Tree Oil    
10% 70 11
1% 0 50
10% 35 26
1% 0 81
10% 50 0
1% 26 75
Copper oleate    
10% 0 40
1% 0 43
10% 80 0
1% 23 65


The mechanism of action of these compounds is not known; however, some monoterpenoids and tetralin derivates do have neurotoxic effects (8, 9). Increasing the concentration of monoterpenoids or tetralin in existing pediculocides might improve insecticidal activity, but may also increase the number of reported cases of contact dermatitis or symptoms of overdose. Further laboratory work is needed in order to 
establish dose mortality curves and long-term safety data before these chemicals can be assessed using clinical trials. The promotion of commercially available essential oils as treatments for head lice should be discouraged until more data is available.


  1. Downs AMR, Stafford KA, Coles GC. Head lice: prevalence in school children and insecticide resistance. Parasitol Today 1999;15:1-4.
  2. Nenoff P, Haustein UF, Brandt W. Antifungal activity of the essential oil of Malaleuca alternifolia (tea tree oil) against pathogenic fungi in vitro. Skin Pharmacol 1996;9:388-394.
  3. Knight TE, Hausen BM. Malaleuca oil (tea tree oil) dermatitis. J Am Acad Dermatol 1994; 30:423-427.
  4. Burgess I. Carbaryl lotions for head lice – new laboratory tsts show variations in efficacy. Pharma J 1990; 12:159-161.
  5. Iannantuono Rf, Devoto F, Saitta MF, Valicenti MR, Gomez F, Gonzalez C, et al. Pediculicidal activity of antidandruff shampoo in a 1% copper oleate formulation. Adv Ther 1997; 14:134-139.
  6. Nelson SM, Pink RC. Solutions of metal soaps in organic solvents. Part IV. Direct-curent conductivity in solutions of some metal oleates in toluene. J Chem Soc 1954: 4412-4417.
  7. Busvine JR. Evidence from double infestations for the specific status of human head lice and body lice (Anoplura). Systematic Entomol 1978;3:1-8.
  8. Lee S, Tsao R, Peterson C, Coats JR. Insecticidal activity of monoterpenoids to western corn rootworm (Coleoptera: Chrysomelidae), two-spotted spider mite (Acari:Tetranychidae), and house fly (Diptera:Muscidae). J Econom Entomol 1997;90:883-892.
  9. Wyrick DW, Booth RG, Myers, AM, Owens CE, Kula NS, Baldessarini RJ, et al. Synthesis of 1-phenyl-3-1,2,3,4-tetrahydronathphalenes as ligands for a novel receptor with -like neuromodulatory activity. J Med Chem 1993; 35:2542-2551.

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 1: Allergy Asthma Proc. 2003 Jan-Feb;24(1):73-5.  

Immediate systemic hypersensitivity reaction associated with topical application of Australian tea tree oil.

Mozelsio NB, Harris KE, McGrath KG, Grammer LC.

Division of Allergy-Immunology, Ernest S. Bazley Asthma and Allergic Diseases Center, Department of Medicine, Northwestern Memorial Hospital, Northwestern University Medical School, Chicago, Illinois, USA.

Australian tea tree oil has been used as a veterinary antiseptic for many years and, more recently, has been extended into human use. There have been many reports of allergic contact dermatitis and toxicity reactions, but it has never been implicated in immediate systemic hypersensitivity reactions. A 38-year-old man experienced immediate flushing, pruritus, throat constriction, and lightheadedness after topical application of tea tree oil. Our purpose was to determine whether this represented an immunoglobulin E (IgE)--mediated reaction. Skin-prick and intradermal testing was performed, as well as enzyme-linked immunosorbent assays for specific IgG and IgE against tea tree oil. The patient had a positive wheal and flare reaction on intradermal testing with tea tree oil. All five patient controls were negative on skin testing. No specific IgG or IgE was detected. We present the first reported case of an immediate systemic hypersensitivity reaction occurring after topical application of Australian tea tree oil, confirmed by positive wheal and flare reaction on skin testing.

Publication Types:
  • Case Reports

PMID: 12635581 [PubMed - indexed for MEDLINE]

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tea tree oil

What Is It?
Health Benefits
Dosage Information
Guidelines for Use
General Interaction
Possible Side Effects

What Is It?

It was centuries ago that Australian aborigines probably first started plucking leaves from a native tree (Melaleuca alternifolia) to treat skin infections. In 1770, sailors from Captain Cook's expedition to the South Seas ventured ashore at New South Wales and brewed a tea using the leaves of the same tree. This event engendered the herb's English name "tea tree"--which is actually something of a misnomer because the Melaleuca species bears no relation to the Camellia species, the usual source of tea leaves.

Today, an aromatic oil with a fragrance reminiscent of nutmeg is steam-distilled from the Melaleuca leaves. Because the Melaleuca alternifolia grows only in Australia, that country is now the major source of tea tree oil, exporting some 700 tons of annually. Tea tree products are often referred to as "melaleuca oil." The pure oil is colorless to pale yellow.

Health Benefits

High-quality tea tree oil contains 40% or more of terpinen-4-ol, the ingredient that fights harmful bacteria and fungi and makes the oil so effective in preventing and fighting infection in cuts, scrapes, insect bites, and stings.

Specifically, tea tree oil may help to:

  • Treat cuts, scrapes, insect bites and stings, and other minor skin wounds and irritations. Tea tree oil blends rapidly and easily with the skin's own oils. In the process, the oil alters the chemical barrier of the skin, making it less hospitable to the growth of fungi and other organisms. In these ways, tea tree oil not only lessens the chance of infection, it also promotes healing and reduces the likelihood of scarring.

  • Fight fungal nail infections, jock itch, and athlete's foot. Tea tree oil has been shown to be effective in countering Trichophyton, the fungus that causes numerous topical infections, including athlete's foot and jock itch.

  • Shorten the course of vaginal yeast infections. Two of the organisms that cause these discomforts, Candida albicans and Trichomonas vaginalis, apparently succumb to the actions of tea tree oil.

  • Gently control acne. Even severe cases of acne have been shown to benefit from anti-acne preparations that contain up to 15% tea tree oil, an effect that can be explained by the oil's antibacterial and skin-healing properties. In one study conducted in Australia, a comparison was made between a gel containing 5% tea tree oil and a traditional 5% benzoyl peroxide acne lotion. The products proved similar in their effectiveness against pimples, although the herbal preparation worked more slowly. It was notable, however, that the product containing the tea tree oil caused significantly less dryness, redness, scaling, and itching to the surrounding skin.

  • Treat dandruff and head lice. According to one study, a 5% solution of tea tree oil is effective against Pityrosporum ovale, a fungus that can cause dandruff. In a laboratory analysis of tea-tree chemistry, substances were discovered that can kill head lice. But human research is still needed, especially since the skin of children (a population particularly susceptible to lice) may be overly sensitive to tea tree oil.

  • Curtail warts. Tea tree oil is sometimes recommended for warts, which are caused by viruses. More research is needed to determine whether the oil is truly effective for this purpose, but it certainly does not seem to cause any complications.

    Note: Tea tree oil has also been found to be useful for a number of other disorders. For information on these additional ailments, see our Dosage Recommendations Chart for Tea Tree Oil.

  • Forms

    • suppository
    • oil
    • gel
    • cream

    Dosage Information

    Special tip:

    --Look for tea tree oil derived only from the Melaleuca alternifolia tree. Oil from other species can have a high percentage of cineole, a compound that can irritate the skin and hinder the oil's active ingredients from providing any therapeutic benefit.

  • For minor skin wounds, insect bites and stings, and irritations: Cleanse the wound and apply one or two drops of tea tree oil to the affected area two or three times daily.

  • For nail infections: Rub tea tree oil on the nail twice a day.

  • For athlete's foot: Apply tea tree oil or cream to affected areas twice a day and/or use it in a foot bath. For a foot bath: Put 20 drops of tea tree oil in a small basin of warm water and soak the feet for 15 minutes, two or three times a day. Dry the feet thoroughly after soaking and apply a drop or two of oil to the affected area.

  • For vaginal yeast infections: Use a tea tree oil vaginal suppository, available at health-food outlets, every 12 hours for up to five days.

  • For acne: Apply a drop or two to each acne lesion three times a day.

  • For warts: Put a few drops of the oil on a small gauze compress and tape it over the wart at bedtime. Remove it in the morning. Repeat until the wart heals.

    Be sure to check out our Dosage Recommendations Chart for Tea Tree Oil, which lists therapeutic dosages for specific ailments at a glance.

  • Guidelines for Use

  • When buying a topical antifungal preparation advertised to contain tea–tree oil, make sure the oil is from M. alternifolia and is one of the first ingredients listed.

  • Tea tree oil is found in various skin-care and beauty products (shampoos, soaps, and so on) but often in amounts so minuscule that it provides virtually no antibacterial effect. To learn if a particular product can produce the benefits of tea tree oil, request information from the manufacturer about studies supporting such a claim.

  • Some toothpastes contain tea tree oil. However, because the oil is dangerous if swallowed, only very small amounts are included. This makes the products safe, but essentially nullifies any bacteria-fighting benefits they claim to have.

  • General Interaction

    There are no known drug or nutrient interactions associated with tea tree oil.

    Possible Side Effects

  • Tea tree oil can irritate sensitive skin, especially in the vaginal area. It can also prompt an allergic reaction in some people. As a safety precaution, dab a small amount on your inner arm with a cotton swab before using the oil or a product that contains it. If you are allergic, your arm will quickly become red or inflamed.

  • Cautions

  • Never ingest tea tree oil. It is for external use only, and should never be applied around the eyes.

  • If you accidentally ingest the oil, immediately contact a doctor or a poison control center.

  • Consult your doctor before replacing any prescription medications with tea tree oil.
  • Ailments


    Apply a drop or two to each acne lesion 3 times a day.
    Athlete's Foot
    Apply oil or cream to affected areas twice a day and/or use as a footbath.
    Cuts and Scrapes
    Apply cream to wound 3 times a day in place of aloe or lavender oil.
    Insect Bites and Stings
    Apply 1 drop of oil to skin several times a day, or as needed.
    Put several drops on a compress. Use overnight until the wart heals.

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    Disclaimer: All material provided in the WholeHealthMD website is provided for educational purposes only. Consult your own physician regarding the applicability of any opinions or recommendations with respect to your symptoms or medical condition.

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