While the uses of eucalyptus oil exist in plenty, the same has some side effects as well. These include convulsions, diarrhea, drowsiness, vomiting, dizziness, abdominal pain, etc., and are normally triggered when it is used in large amounts. It being a high stimulant oil, should not be used during pregnancy, or by people suffering from high blood pressure, epilepsy, and other heart diseases. Hence, we can conclude that, although eucalyptus oil has numerous benefits, one has to be careful when using it, especially in case of oral use.