Substance use disorder
Also known as: SUD, addiction
Substance use disorder is a psychiatric condition in which a person continues using alcohol or drugs despite significant impairment or distress. Diagnosis is based on a pattern of impaired control, social problems, risky use, and physical dependence.
Substance use disorder (SUD) is the DSM-5 diagnosis for a problematic pattern of substance use that causes clinically significant impairment or distress. It replaced the older split between substance "abuse" and "dependence" with a single disorder diagnosed on a spectrum, and it can apply to alcohol, opioids, stimulants, cannabis, sedatives, and other substance classes.
The diagnostic criteria fall into four clusters: impaired control (using more than intended, failed attempts to cut down, craving), social impairment (failing obligations at work, school, or home; continued use despite relationship problems), risky use (use in hazardous situations or despite known harm), and pharmacological criteria — tolerance (needing more for the same effect) and withdrawal (physical symptoms when use stops). Severity is graded by how many criteria are met: mild, moderate, or severe.
SUD is understood as a chronic, relapsing condition involving changes in the brain's reward circuitry, not a failure of willpower. Treatment combines behavioral therapies, support programs, and — for some substances — medications, along with management of withdrawal and monitoring for relapse.
Substance use disorder is tested across several exams. The NCLEX covers it within psychiatric nursing — screening, withdrawal assessment, and safe nursing interventions — while USMLE Step 1 tests the diagnostic criteria, substance-specific intoxication and withdrawal syndromes, and treatment pharmacology in behavioral science. It also appears on life and health insurance licensing exams, because the Affordable Care Act lists mental health and substance use disorder services among the ten essential health benefits that individual and small-group plans must cover.
Key takeaways
- SUD is a DSM-5 diagnosis defined by continued substance use despite significant impairment or distress.
- Criteria cluster into impaired control, social impairment, risky use, and tolerance/withdrawal.
- Severity is graded mild, moderate, or severe by the number of criteria met.
- It is treated as a chronic, relapsing brain-based condition, not a lack of willpower.
- The NCLEX and USMLE Step 1 test SUD clinically, and insurance exams cover it as an ACA essential health benefit.