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Eucalyptus globalus, also known as blue gum, is a common ornamental tree in many states, including California. The leaves of the tree contain eucalyptus oil, which is a medication for many maladies such as asthma, sore throat and nasal congestion, and is taken internally for that purpose. The oil of the eucalyptus is also spread on the skin to deter mosquitoes. Ingesting large quantities of eucalyptus oil can be deadly.

Cold Medication

Cold remedies may contain eucalyptus oil, since it acts as a decongestant. According to the National Institutes of Health the oil is an over-the-counter product, and treats inflammation in the upper respiratory system. Some cold medications provide the product as an inhalant, and other remedies provide it in a form that is eaten, such as cough and cold lozenges.

Leaves in Food

Steaming the leaves extracts the eucalyptus oil. The main active ingredient in this oil is the chemical cineole, also known as eucalyptol. Some types of food use cineole as a flavoring, and small quantities of eucalyptus, including leaf fragments, are safe for human consumption. Government regulations allow different quantities of cineole in food, depending on the type of food--alcoholic beverages may include 1 part per million and candy may have 150 parts per million.

Eucalyptus Tea

Eucalyptus tea is made from eucalyptus leaves and has antibacterial and antiseptic effects. According to the University of Maryland, as part of an alternative treatment regimen adults can steep tea bags containing half a teaspoon of eucalyptus leaves per cup of water for a period of up to 15 minutes to produce medicinal tea. Children should not drink this tea or eat eucalyptus leaves at all since they are at high risk for an overdose.

Overdose Symptoms

Eucalyptus overdose symptoms affect several systems in the body and require immediate professional treatment. Symptoms include fast and shallow breathing, loss of balance and weakness, and a quick and weak heartbeat. You may also feel nausea and even vomit, but do not force yourself to vomit unless a physician or other professional tells you to do so.

Duration Effects

Because of the dizziness and drowsiness that are side effects of ingesting eucalyptus oil, anyone who has recently eaten eucalyptus leaves should not drive a car or operate machinery. A patient who survives an overdose for two days should recover.