The Full Story
Tea tree oil comes from the leaves of an Australian tree called Melaleuca alternifolia. It is an essential oil with a long history of use as a natural remedy for skin ailments and other conditions. Unfortunately, sometimes "natural" is confused with "non-toxic" or "non-poisonous".
Tea tree oil, like many other "natural" substances, can indeed be poisonous if used in the wrong way, especially if swallowed. In 2011, Poison Control received nearly twice as many calls about tea tree oil than any other named essential oil, including cinnamon oil, clove oil, and eucalyptus oil. More than 10 percent of people exposed to tea tree oil were treated in a hospital or doctor's office.
Tea tree oil is sold as a pure essential oil, in over-the-counter and herbal remedies for skin conditions, and as an ingredient in household cleaning products.
Traditional uses: The National Library of Medicine (NLM) lists a number of traditional or theoretical uses of tea tree oil. NLM notes that these uses have not all been tested for safety or effectiveness. Skin conditions feature prominently in traditional uses of tea tree oil: bruises, burns, canker sores, corns, eczema, insect bites, psoriasis, rosacea, scabies, skin infections, etc. A number of respiratory conditions are noted: colds, cough, bronchial congestion, and nose and throat irritation. A wide variety of other conditions are also listed as traditional uses: melanoma, body odor, and infections of the bone and prostate.
Medical studies: A number of studies have examined the effects of tea tree oil on individual cells; many of these indicate some activity against microbes and fungi. There are few studies in humans that affirm the effectiveness and safety of tea tree oil and that have been successfully repeated. So far, studies do not support the idea that tea tree oil boosts the immune system.
A few studies of effects on skin conditions include:
- A 1994 study compared tea tree oil to the antifungal drug clotrimazole in treating fingernail fungus. Both had approximately the same effect.
- A 1990 study comparing tea tree oil to benzoyl peroxide in treating acne found that both were effective, tea tree oil took longer to work, and the tea tree oil patients had fewer side effects.
- A 1992 study of tea tree oil, the antifungal drug tolnaftate, and a placebo showed that tea tree oil was no better than the placebo in curing the fungus infection, though it did improve the patient's symptoms as much as tolnaftate.
Side effects: Tea tree oil can sometimes irritate the skin, especially in higher concentrations. It has also caused allergic skin reactions. There is a single report of breast enlargement in a young boy who used products containing lavender oil and tea tree oil; laboratory studies of the oil itself indicated that tea tree oil may have hormonal effects. (It's likely that if this were a common effect it would have been noted long ago; the authors published the information so that physicians could consider essential oils when treating boys with breast enlargement.)
Poisoning: Tea tree oil is known to be poisonous if swallowed. A child who swallowed a small amount given to him by mistake went into a coma (from which he recovered). Tea tree oil should NOT be taken by mouth for any reason, even though some traditional uses include tea tree oil as a mouthwash, treatment for bad breath, and treatment of toothache and mouth ulcers.
Tea tree oil and pets: Veterinary toxicologists have reported that large amounts of tea tree oil applied to the skin of cats and dogs caused poisoning. Symptoms have included muscle tremors, weakness, difficulty in walking, low body temperature, and excessive salivation. With pets, as with people, following label instructions is essential.
Non-medicinal uses: Tea tree oil is found in some household products, including cleaning products. It is promoted as being "natural" and "better for the environment". As noted above, "natural" does not necessarily mean "non-toxic" or "non-poisonous"; tea tree oil is irritating to some people and is poisonous to swallow. Also, studies would be needed to determine if tea tree oil is environmentally safe. These products should be used according to label instructions and stored safely in their original containers, out of reach of children, and apart from medicines and food.
The bottom line: Tea tree oil has been used as a "natural" remedy for a long time, especially for skin afflictions. There is some scientific evidence that tea tree oil can be effective for certain skin conditions. It is poisonous if swallowed and so should not be used in or around the mouth at all.
If someone may have swallowed tea tree oil, immediately check the webPOISONCONTROL® online tool or call Poison Control at 1-800-222-1222. Don't wait to see what will happen first, as swallowed tea tree oil can cause dangerous poisoning in less than thirty minutes.
Rose Ann Gould Soloway, RN, BSN, MSEd, DABAT emerita
For More Information
Tea tree oil (U.S. National Library of Medicine)
Bassett IB, Pannowitz DL, Barnetson RS. A comparative study of tea tree oil vs. benzoyl peroxide in the treatment of acne. Med J Aust 1990;153:455-8.
Mowry JB, Spyker DA, Cantilena LR, Bailey JE, Ford M. 2012 Annual report of the American Association of Poison Control Centers' National Data Collection System (NPDS): 30th annual report. Clinical Toxicology. 2013;51:949-1229.
Buck DS, Nidorf DM, Addino JG. Comparison of two topical preparations for the treatment of onychomycosis: Melaleuca alternifolia (tea tree) oil and clotrimazole. J Fam Pract.1994;38:601-5.
Henley DV, Lipson N, Korach KS, Bloch CA. Prepubertal gynecomastia linked to lavender and tea tree oils. N Engl J Med 2007;356:479-85.
Morris, M. C., Donoghue, A., Markowitz, J. A., and Osterhoudt, K. C. Ingestion of tea tree oil (Melaleuca oil) by a 4-year-old boy. Pediatric Emergency Care. 2003;19:169-171.
Tong MM, Altman PM, Barnetson RS. Tea tree oil in the treatment of tinea pedis. Australia J Dermatol 1992;33:145-9.
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.