drug addiction

n. A state in which a person is both physiologically and psychologically dependent on a drug. Thus the person’s metabolism has shifted to deal with the chronic presence of a drug, manifested by need for increased doses of the drug to obtain the same effects and physiological disequilibrium upon withdrawal of the drug, which may produce unpleasant and/or life-threatening symptoms. In addition the person does not know how to cope with daily life without the drug and has habitual patterns associated with drug use which are resistant to change.