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Tea tree oil is an essential oil that is extracted from the leaves and small branches of the tea tree, Melaleuca alternifolia, a native of Australia. Another name for tea tree oil is melaleuca oil.

The oil is a colourless or pale yellow liquid with a 'medicinal' smell. It contains over 100 compounds, including terpenes and alcohols. Use of the extracted oil of the plant rather than the plant material itself, started back in the 1930s.

The pure oil is readily available in ‘health food’ shops, usually in 10mL opaque bottles with a dropper top. Tea tree oil is an ingredient in numerous products for pets, including shampoos, creams, lotions, insect repellents and ear cleaners. None are licensed as medicines in the UK.

In laboratory experiments tea tree oil has been shown to have antibacterial, antifungal, antiviral, antiprotozoal and anti-inflammatory effects. Some people use tree oil because they perceive it as a ‘natural’ or ‘non-chemical’ treatment. But there is a lack of evidence that it has any beneficial effects in treating disorders or in controlling fleas in pets. And the natural chemicals in tea tree oil and other essential oils can cause harms and can be dangerous for pets. 

  • Tea tree oil can irritate the skin causing redness, itching and rash.
  • If pure tea tree oil is applied to a pet's skin it will quickly be absorbed into the body, either directly across the skin, or from the stomach if the animal has licked its skin while grooming. 
  • Even if the pure oil is diluted before being applied it may be ingested by the animal through grooming, and cause toxicity. 
  • Cats may be more likely than dogs to have toxicity because of their grooming behaviour.
  • The natural chemicals in tea tree oil can cause serious toxicity to pets, including death.
  • Proprietary products containing low concentrations of tea tree oil that are intended for use on the skin or fur in small amounts would not be expected to cause toxicity.

The signs of toxicity can occur within 2–8 hours of application of tea tree oil to the skin.

  • The animal's breath, urine, faeces and any vomited stomach contents may smell strongly of the oil.
  • The animal might have weakness, tremors, odd movements, behavioural disorders and depression.
  • Recovery often occurs within 24 hours, but can take longer.
  • In severe cases, the animal may collapse, go into a coma or have convulsions.
  • Deaths have been reported.
  • There is very limited information on the use of tea tree oil in the treatment of disorders in pets and so the benefits are uncertain.
  • There is no evidence that tea tree oil is effective in controlling fleas.
  • Pure essential oils, including tea tree oil (even if diluted), should never be used on pets, either given by mouth or applied to the skin or fur. Deaths have been reported in pets after application of tea tree oil to the skin or fur.
  • Any pure essential oil on the skin should be washed off promptly with detergent and water. 
  • If the animal becomes unwell, immediately contact a vet or the Animal Poison Line.
  • Pure essential oils should be stored safely out of sight, and out of reach of pets and children. The lid should be replaced securely, and any drips down the side of the bottle cleaned.
  • ‘Natural’ does not mean safe.


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Wismer T, Means C. Toxicology of newer insecticides in small animals. Vet Clin Small Anim 2012; 42: 335-47.