There may have been unsuccessful efforts to cut down on the amount of use. A great deal of time may be spent in obtaining the substance or recovering from its effects. There may be a significant impact on one's work, home or social life, or mental or physical health. Both differ greatly from one drug to another. There is no illegal drug that does not have serious adverse consequences.
Drug dependence can develop through either psychological or physical processes.
Psychological dependence is characterized by emotional and mental preoccupation with the drug's pleasurable effects. One craves more to regain the stimulation, elation, sense of well-being, or other psychological pleasures from the drug. Psychological dependence also occurs when one develops a lifestyle that depends upon drug use. Physical dependence occurs when the body adjusts to the presence of a drug, so that physical symptoms usually involving discomfort and pain occur when the drug is withdrawn. The addict craves more drugs in order to avoid or alleviate the pain.