For chemical addiction, it refers to a specific group of psychophysiological symptoms or impaired social functioning that occurs after stopping the use of a drug or reducing the dose of use or occupying the receptors with antagonists. The mechanism is due to the rebound of adaptation (rebound) caused by the sudden discontinuation of the drug after long-term use. Symptoms and their severity are related to the substance used and the dose, and can be relieved by reuse. Withdrawal symptoms due to different drugs vary according to their pharmacological properties and are generally manifested as symptoms opposite to the pharmacological effects of the drug used. For example, alcohol (central nervous system depressants) withdrawal is followed by a cluster of symptoms such as euphoria, sleeplessness, and even seizure-like epilepsy. For non-chemical addiction, this refers to a specific group of psychophysiological symptoms that occur after stopping or reducing the frequency of certain behaviors, or impaired social functioning. Withdrawal after some substance addictions is often unbearable and fatal, and often requires urgent medical intervention!