Tea tree oil is an aromatic essential oil made by crushing the leaves of the plant Melaleuca alternifolia. This is a plant in the family Myrtaceae. Other plants in this family include guava, eucalyptus, clove and allspice.

Tea tree is antibacterial, so it is used as an ingredient in lots of beauty products, predominantly skin care and cleansers.

Tea tree oil is a common trigger for allergic contact dermatitis. When tea tree becomes oxidised, its content can increase in peroxides, which makes it even more likely to cause skin irritation. In this instance, oxidation happens when products are exposed to the air for long periods of time or sit in the sun. The effects of oxidation should be obvious where there is a change in the smell of the product or a visible change in the colour and thickness of the oil.

Some of the chemicals in tea tree that may be the culprit for allergic reactions are sesquiterpenes, monoterpenes and limonene, among other essential oils. It also contains eugenol which is a chemical compound which can also cause contact allergies - this is what gives the food flavour and fragrance. These contact reactions are sometimes mistaken for a true IgE food allergy.

It is generally hailed as a natural antibacterial remedy, but tea tree oil should not be ingested as it can be toxic, especially in children. Natural does not always equate to safe.

Tea tree til is often associated with allergic contact dermatitis. Symptoms of this include itching and swelling of the skin and a visible red irritated skin.

There are no allergens currently associated with tea tree oil.

You can find the most up to date information on the Cross Reactivity Tool.

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