Paracelsus (1493-1541) the Swiss physician whose radical ideas influenced the development of medicine wrote in about 1530 "all things are poisons. It is only the dose which make a thing poison". Even water and salt which are normally harmless may cause illness or death if taken in excess.
Eucalyptus oil is very concentrated. It is the essence of the tree and needs to be used sparingly and with care.
Although eucalyptus oil is toxic if ingested in excessive quantities Australia is the only country in the world to legislate that products containing 25% or more eucalyptus oil must be labelled poison and packed in a poison container. The container must be sealed with a child-resistant closure.
Products containing less than 25 per cent eucalyptus oil can be sold without having to be labelled poison, without having to be packed in poison containers and without being sealed with a child-resistant closure. Their use is not restricted in any way.
Manufacturers often incorporate eucalyptus oil into cough lozenges, cough syrups, toothpastes, mouth washes and as a flavour ingredient in foods.
Home-made oral preparations containing pure eucalyptus oil are not recommended unless the measurement of the amount of eucalyptus oil used is very accurate. The highly respected and authoritative German Commission E monograph on eucalyptus oil under 'Dosage' states, for internal use, a daily dose of 0.3 to 0.6g.
It is acceptable to take eucalyptus oil orally provided the dosage is kept within this use range. It is not advisable to take eucalyptus oil over a long period (a year or more) as it may cause liver damage.
The acute oral toxicity LD50 of eucalyptus oil for rats is 2.48g/kg body weight. Evidence indicates the LD50 for humans is probably about the same. There have been no reported deaths due to the ingestion of eucalyptus oil in the past 50 years.
If eucalyptus oil is accidentally swallowed, urgent hospital treatment may be required. For advice, contact a Poisons Information Centre (Australia telephone 13 11 26) or a doctor at once. Do not induce vomiting.
Where accidental poisoning has occurred there have been no reports of long-term side effects. Other household products such as paracetamol, oil of wintergreen, methyl salicylate, kerosene and petrol have proved to be much more dangerous.
The acute dermal toxicity of eucalyptus oil exceeds 5g/kg body weight. A patch test using full-strength eucalyptus oil for 24 hours produced no reaction in 20 subjects. Ten per cent of eucalyptus oil in petrolatum produced no irritation in a 48 hour closed patch test in 25 human subjects. This means most people will not have any adverse reaction from eucalyptus oil when applied to the skin.
Very occasionally hypersensitivity has been reported in susceptible individuals. Anyone who is hypersensitive should cease using the product immediately. There have been no reports of phototoxicity (sensitivity to light).
Eucalyptus oil is flammable and should be kept away from flames, heat and sparks.
Eucalyptus oil is extremely concentrated and contact should be avoided with the following: eyes, mucous membranes, lips, tongue, polished furniture and some plastic surfaces. Materials such as suede, denim, silk and non-colourfast materials should always be patch tested before using.