Heroin/Opiate addiction is a chronic, relapsing disease that is characterized by compulsive drug seeking and drug use. Molecular and neurochemical changes in the brain also occur. Seeking and using drugs becomes the primary purpose in life of the addicted person. Physical dependence develops with higher doses of the drug so that withdrawal symptoms occur if use is reduced abruptly. Physical dependence and withdrawal symptoms are also accompanied by cravings that may last for weeks or months after physical withdrawal.