Tea Tree (Melaleuca Oil)
Tea tree oil (melaleuca oil) is being marketed for the treatment of
many disorders in humans and in animals. The active ingredients in
tea tree oil have a similar structure and action as turpentine.
Melaleuca oil comes from the Australian tea tree (Melaleuca
alternifolia). It is also known as tea tree oil and Australian tea
tree oil. The oil is reputed to have mild antibacterial and
antifungal properties and is marketed as a natural remedy in both
veterinary and human medicine.
Animals and humans are getting poisoned from topical use and from
accidental ingestion of tea tree oil. I have numerous reports on file of
toxic reactions from tea tree oil being used topically to treat fleas in
animals, and one case of avian poisoning.
Melaleuca oil is highly lipophilic and can be absorbed through intact
skin to cause systemic toxicity. Pets grooming themselves may also
ingest some topically applied oil.
The owner of a lovebird applied one drop of tea tree oil to a
bleeding blood feather of her lovebird. Within 10 minutes the bird
collapsed and was on the bottom of the cage. The bird was rushed to
the vet. Fortunately, with intensive care treatment, the bird
recovered uneventfully.
Application of tea tree oil to control fleas has resulted in death in
kittens.
The following are abstracts from the veterinary and medical literature:
.Villar D, Knight MJ, Hansen SR, Buck WB. Toxicity of melaleuca oil and
related essential oils applied topically on dogs and cats. Vet Human
Toxicol. 1994;36(2):139-142.
Abstract: "Cases of melaleuca oil toxiosis have been reported by
veterinarians to the National Animal Poison Control Center (NAPCC) when
the oil was appled dermally to dogs and cats. In most cases, the oil was
used to treat dermatologic conditions at inappropriate high doses. The
typical signs observed were depression, weakness, incoordination and
muscle tremors. The active ingredients of commercial melaleuca oil are
predominantly cyclic terpenes. Treatment of clinical signs and
supportive care has been sufficient to achieve recovery without sequelae
within 2-3 days."
"Toxicity:
The most common clinical signs reported to the Animal Poison Control
Center by veterinarians with adverse reactions in dogs and cats after
dermal exposure of melaleuca oil include ataxia, incoordination,
weakness, tremors, behavioral disorders and depression.
The acute toxcicity (rabbit dermal LD 50 and rat oral LC 50) for the
major terpenic compounds (linalool, ocimene, alpha-terpinene,
1,8-cineole, terpinolene, camphene) ranges between 2 and 5 g/kg body
weight, which is considered a moderately toxic range. From a
toxicologic standpoint melaleuca oil can be compared to oil of
turpentine, which is readily absorbed from the gastrointestinal tract
and skin.
The highly lipophilic nature of melaleuca oil not only potentiates its
antiseptic properties on the skno, but also its dermal absorption, which
may account for the episodes reported to the NAPCC.
Treatment of Exposures: There is no specific antidote for the adverse
reactions caused by dermal overexposure to melaleuca oil and related
essential oils. Basic supportive care shoule include monitoring
respiratory and cardiovascular functions as well as for checking for
possible hypothermia; heat support should be provided as needed. For
topical exposures resulting in toxicosis, a bath with mild
non-insecticidal shampoo is recommended to remove residual amounts of
the oil from skin and prevent further absorption. Intravenous fluids and
glucose should strenthen the animal, overcome hypotension, and aid renal
elimination."
. Jacobs MR, Hornfeldt. Melaleuca oil poisoning. Clinical Toxicology
1994;32:461-464.
Abstract: "A 23-month-old boy became confused and was unable to walk
thirty minutes after ingesting less than 10 mL of T36-C7, a commercial
product that contained 100% melaleuca oil. The child was referred to a
nearby hospital. His condition improved and he was asymptomatic within 5
hours of ingestion. He was discharged home the next day. Melaleuca oil,
extracted from the Melaleuca alternifolia, contains 50-60% terpenes and
related alcohols. This case report suggests that ingestion of a modest
amount of a concentrated form of this oil may produce signs of
toxicity."
. Del Beccaro MA. Melaleuca oil poisoning in a 17-month-old.
Vet Human Toxicol 1995;37:557-8.
Abstract: "Ingestion of significant quantities of melaleuca oil or
Australian tea tree oil has been described only once in the medical
literature. This report describes a 17-month-old male who ingested less
than 10 mL of the oil and developed ataxia and drowsiness. Emergency
physicians, poison control personnel and pediatricians should be aware
of potential toxicity from this product."
.Elliott C. Tea tree oil poisoning. Med J Australia 1993;159:830-831.
A 60-year-old male ingested 0.5 teaspoonful of tea tree oil and
developed a dramatic rash, malaise and neutrophil leucocytosis.
. Seawright A. Tea tree oil: comment. Med J Australia 1993;159:831.
This author commented that some tea tree oils contain a high
concentration of 1,8-cineol (eucalyptol, cajeputol). Toxicity similar to
that of eucalyptus oil would be expected. Toxic does of eucalyptus oil
range from 5-30 mL in humans, with symptoms including respiratory
depression, coma and death.
. deGroot AC, Weyland JW. Systemic contact dermatitis from tea tree oil.
Contact Dermatitis 1992;27:279-280.
This report in a human showed that this reaction was caused by the
allergin, cineol present in the tea tree oil.
CONCLUSION: One should be aware that that tea tree oil (melaleuca oil)
is potentially toxic to animals and avians when applied topically. Use
this information and your own judgment when deciding if you feel
comfortable in applying tea tree (melaleuca) oil to your pets. Tea tree
oil should NOT be applied to avians.
Gillian Willis
Vancouver, B.C.
Copyright © Gillian A.Willis. Permission to re-use any
part of this text (whole or in part) must be obtained from the
author.