Eucalyptus oil is refined from the leaves by steaming . It can be used for cleaning , deodorising , and in very small amounts in food supplements , especially sweets , cough drops and decongestants . Eucalyptus oil is readily steam distilled from the leaves and can be used for cleaning , deodorising , and in very small quantities in food supplements , especially sweets , cough drops , toothpaste and decongestants .