Opioid withdrawal

Opioid withdrawal is a cluster of physical and psychological symptoms that can follow reducing or stopping opioids after physical dependence develops. Its severity and timing vary with the opioid, exposure, and individual.

Opioid dependence: A physiological adaptation in which stopping or reducing opioids can produce withdrawal symptoms. It is the physical adaptation that makes withdrawal possible.
Opioid withdrawal management: Clinical care that reduces withdrawal symptoms and supports ongoing treatment for opioid use disorder. It addresses symptoms while helping prevent return to unsafe opioid use.
Opioid use disorder: A chronic medical condition involving a problematic pattern of opioid use that causes significant impairment or distress. Withdrawal may occur in opioid use disorder, but physical dependence alone does not establish the diagnosis.
Physical dependence: A physiological adaptation in which reducing or stopping a drug can cause withdrawal. It is not synonymous with addiction or opioid use disorder.
Opioid receptors: Cell-surface receptors that respond to endogenous opioid peptides and opioid drugs. Withdrawal follows changes in signaling through these receptors.
Buprenorphine: A partial opioid agonist used to treat opioid use disorder and pain. It can relieve withdrawal and support treatment when started at an appropriate time.
Tolerance: A reduced response to a drug after repeated exposure, often requiring more for the same effect. Tolerance and withdrawal can develop together, but they are distinct adaptations.
Addiction: A pattern of compulsive substance use despite harmful consequences. Withdrawal is a physical syndrome; addiction describes a broader pattern of behavior and impairment.
Locus coeruleus: A brainstem nucleus that supplies much of the brain's norepinephrine. Its heightened activity contributes to autonomic symptoms during withdrawal.
Methadone: A long-acting opioid agonist used to treat opioid use disorder and pain. It suppresses withdrawal and cravings through sustained opioid-receptor activation.

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