A problematic pattern of opioid use that causes significant impairment or distress. A diagnosis is based on specific criteria such as unsuccessful efforts to cut down or control use, or use resulting in social problems and a failure to fulfill obligations at work, school, or home, among other criteria. Opioid use disorder is preferred over other terms with similar definitions, “opioid abuse or dependence” or “opioid addiction.”

Adaptation to a drug that produces symptoms of withdrawal when the drug is stopped.

Reduced response to a drug with repeated use.