What is withdrawal? How long does it last?

Withdrawal describes the various symptoms that occur after long-term use of a drug is reduced or stopped abruptly. Length of withdrawal and symptoms vary with the type of drug. For example, physical symptoms of heroin withdrawal may include restlessness, muscle and bone pain, insomnia, diarrhea, vomiting, and cold flashes. These physical symptoms may last for several days, but the general depression, or dysphoria (opposite of euphoria), that often accompanies heroin withdrawal may last for weeks. In many cases, withdrawal can be easily treated with medications to ease the symptoms, but treating withdrawal is not the same as treating addiction.