Withdrawal is the cluster of unpleasant physiological and psychological symptoms that appear when a person stops or sharply reduces intake of a drug to which the body has become adapted. The specific symptoms depend on the substance. Alcohol withdrawal can include tremor, anxiety, and in severe cases seizures. Opioid withdrawal produces flu-like symptoms, dysphoria, and intense craving.

Withdrawal reflects the opposite of the drug’s acute effects. A drug that suppresses neural activity leaves the system hyper-excitable when removed. The severity and time course vary with dose, duration of use, and individual factors. Some withdrawal syndromes are medically dangerous; others are mainly uncomfortable.

Not every substance produces a clear physical withdrawal syndrome. Psychological dependence—strong craving and difficulty functioning without the drug—can occur even when physical withdrawal is mild. Treatment often combines medical management of acute symptoms with longer-term behavioral and social support.

• Symptoms after cessation of repeated drug use
• Often opposite to the drug’s acute effects
• Severity depends on substance and history of use
• Distinct from psychological craving

Recognition of withdrawal risk is a key element in the safe management of prescribed and illicit psychoactive substances.