What defines drug addiction?

Drug addiction is most accurately defined as a substance use disorder in which drug use becomes difficult to control and continues despite harm. Clinically, it is identified by a problematic pattern of use that leads to impairment or distress, such as craving, repeated unsuccessful efforts to cut down, neglect of responsibilities, risky use, tolerance, or withdrawal. The key issue is not simply how much or how often a person uses a drug, but whether use has become compulsive, persistent, and damaging.

This condition exists on a spectrum from mild to severe. Under DSM-5, substance use disorder is diagnosed when at least 2 of 11 criteria are present within a 12-month period, with severity based on how many criteria are met. That framework is important because it recognizes that a person can have a real clinical problem before it becomes extreme.

Repeated drug use can produce lasting changes in brain circuits involved in reward, stress, learning, and self-control, which helps explain why stopping may become increasingly difficult over time. That does not mean recovery is impossible; it means addiction is a medical condition, not simply a failure of willpower.