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
© Acta Derm Venereol 1999; 79:1-2
LETTERS TO THE EDITOR
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.
MATERIAL AND METHODS
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
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
|Tea Tree Oil
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.
- Downs AMR, Stafford KA, Coles GC. Head lice: prevalence in school children and insecticide
resistance. Parasitol Today 1999;15:1-4.
- 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.
- Knight TE, Hausen BM. Malaleuca oil (tea tree oil) dermatitis. J Am Acad Dermatol 1994; 30:423-427.
- Burgess I. Carbaryl lotions for head lice new laboratory tsts show variations in efficacy. Pharma J
- 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.
- 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.
- Busvine JR. Evidence from double infestations for the specific status of human head lice and body lice
(Anoplura). Systematic Entomol 1978;3:1-8.
- 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.
- 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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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.
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
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
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.
--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
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.
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.
There are no known drug or nutrient interactions associated
with tea tree oil.
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.
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.
Apply a drop or two to each acne
lesion 3 times a day.
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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