tea tree
Meaning of tea tree: An Australian shrub with no relation to tea, whose oil is applied to skin and poisons children who swallow it.
Definition of tea tree
Tea tree is a small Australian tree, Melaleuca alternifolia, of the myrtle family, whose crushed leaves yield an aromatic oil used on the skin. The oil kills bacteria and fungi in laboratory testing and appears in shampoos, acne preparations, antiseptic creams and household products. Despite the name it has nothing to do with the plant that makes tea, nor with green tea extracts.
What is it used for on the skin?
Mild infections and inflammation of the surface: chiefly acne, fungal infection of the foot and nail, dandruff, and head lice. Trials exist for each and the overall picture is modest. The oil generally works better than nothing, more slowly and less completely than the standard treatment it is measured against, and is preferred by some people for being gentler. The active component is a single alcohol called terpinen-4-ol, which makes up most of the oil in preparations meeting the usual quality standard. A different component present in smaller amounts is the main irritant, and brands vary in how much of each they contain, so strength and tolerability are not consistent between bottles.
Why is swallowing it dangerous?
The oil that is fairly well tolerated on skin acts on the brain once absorbed in quantity. Swallowing even a modest amount, which for a small child means a mouthful from an unsecured bottle, causes unsteadiness, drowsiness, confusion and loss of consciousness, sometimes within the hour. It is a recognized cause of poisoning in young children and in pets, particularly cats and dogs, where undiluted oil applied to the coat has produced the same picture. Concentrated oil is not a preparation for internal use in any form, and descriptions listing only its role as a topical antiseptic leave this out completely.
What changes as the oil ages?
It oxidizes. Air, light and warmth convert some components into substances much more likely to provoke an allergic skin reaction, so an old or badly stored bottle causes more rashes than a fresh one. Allergic contact dermatitis from tea tree oil is well recognized, and it can be mistaken for the condition being treated, which leads to yet more of the oil being applied. Undiluted oil irritates skin in its own right even when fresh. As with other plant preparations, among them the leaf extract of the maidenhair tree, content is not standardized the way a prescribed medicine is, and the label names the plant rather than the amount of active compound present.
Also known as
Used in a sentence
The patient had been applying a tea tree preparation to the affected nails.
Good to know
Tea tree oil is for external use, and swallowing it causes unsteadiness, drowsiness and loss of consciousness in small children and in pets, while oil that has oxidized with age is a recognized cause of allergic skin reactions.
Word origin
Where “tea tree” comes from
Melaleuca combines the Greek melas, meaning black, with leukos, meaning white, describing the contrast between a dark trunk and pale papery bark. The English name records early settlers brewing the leaves as a tea substitute.