Substance use disorders (SUDs) are chronic, relapsing brain disorders in which a person continues to use a substance despite significant harm. Addictive substances activate the brain's mesolimbic dopamine reward pathway; repeated use changes reward, stress, and self-control circuits, producing craving, tolerance (needing more for the same effect), and withdrawal (a substance-specific syndrome when use stops). DSM-5-TR also classifies gambling disorder as a non-substance addictive disorder.

DSM-5-TR substance use disorder: a problematic pattern with at least 2 of 11 criteria within 12 months, grouped as impaired control, social impairment, risky use, and pharmacologic criteria (tolerance, withdrawal). Severity: mild 2–3, moderate 4–5, severe 6 or more. Tolerance and withdrawal do not count when they occur only with medically supervised use (e.g., prescribed opioids).

Risk factors: family history of substance use, early age of first use, trauma and adverse childhood experiences, co-occurring mental illness, peer use, and easy access. In adolescents, family substance use history and early initiation are key risks.

Person-first language reduces stigma: "person with an opioid use disorder," not "addict" or "abuser."

Key substance classes

• Substance history: substance, route, amount, frequency, last use, prior withdrawal, seizures or delirium tremens, overdose, injection practices
• Physical signs: needle tracks, nasal septum damage (intranasal cocaine), tremor, jaundice, malnutrition, dental decay (methamphetamine)
• Psychiatric: depression, anxiety, psychosis, suicide risk (high in SUDs)
• Defense mechanisms: denial ("I can stop anytime"), rationalization, projection, minimization
• Family: codependency and enabling (making excuses, covering up consequences)

Alcohol withdrawal timeline

Vital signs are the key early indicator: rising heart rate and blood pressure signal worsening withdrawal.

Wernicke–Korsakoff syndrome (thiamine deficiency)

• Wernicke encephalopathy (acute, reversible if treated): confusion, ataxia, ophthalmoplegia or nystagmus — the full triad is often absent
• Korsakoff syndrome (chronic): severe anterograde amnesia with confabulation

Alcohol withdrawal

• Benzodiazepines are first-line: chlordiazepoxide, diazepam (long-acting), or lorazepam (preferred in liver disease and older adults). Symptom-triggered dosing by CIWA-Ar reduces total dose. Monitor for respiratory depression and oversedation; never combine with alcohol. Phenobarbital is used in some protocols for benzodiazepine-resistant withdrawal.
• Thiamine 100 mg IV or IM before any glucose-containing fluids — glucose can precipitate or worsen Wernicke encephalopathy in thiamine-deficient clients. Higher IV doses are used for suspected Wernicke encephalopathy. Never delay treatment of hypoglycemia: if glucose is low, give dextrose immediately and thiamine at the same time.
• Folic acid, multivitamin, correction of magnesium, potassium, and phosphate; fluids.
• Severe DTs: ICU, continuous monitoring, seizure precautions.

Alcohol use disorder — relapse prevention drugs

Opioid overdose

• Open the airway and support ventilation; give naloxone (IN, IM, or IV); repeat every 2–3 minutes if no response. Naloxone 4 mg nasal spray has been available over the counter in the US since 2023.
• Naloxone's duration can be shorter than the opioid's — observe for recurrent respiratory depression. Expect abrupt withdrawal and possible agitation after reversal.
• Fentanyl adulterated with xylazine may cause sedation that naloxone does not reverse; still give naloxone and support breathing.

Medications for opioid use disorder (MOUD) — the standard of care; reduce overdose death.

Pregnancy: methadone or buprenorphine is recommended for opioid use disorder — do not detoxify; avoid disulfiram.

Opioid withdrawal support: clonidine or lofexidine (monitor for hypotension and bradycardia), antidiarrheals, antiemetics, NSAIDs.

Other substances

• Stimulant intoxication: calm, low-stimulation environment; benzodiazepines for agitation; cooling for hyperthermia; monitor for chest pain, dysrhythmias, stroke. No FDA-approved drug treats stimulant use disorder; contingency management is effective.
• Tobacco: combination nicotine replacement (patch plus gum or lozenge), varenicline (nausea, vivid dreams; the neuropsychiatric boxed warning was removed in 2016, but monitor mood), bupropion (lowers seizure threshold — contraindicated with seizure disorder or eating disorders).
• Benzodiazepine dependence: gradual taper, never abrupt stop.
• Psychosocial: motivational interviewing, CBT, contingency management, 12-step and mutual-help groups.

Listed in priority order.

1. Airway, breathing, and overdose response
   • Sudden dyspnea, cyanosis, and decreased consciousness in a heroin user → suspect overdose with respiratory depression; open airway, ventilate, give naloxone
2. Withdrawal safety
   • CIWA-Ar or COWS as ordered; vital signs closely (pulse, blood pressure, temperature)
   • Seizure precautions, bed low, padded rails per policy; quiet, well-lit, low-stimulation room to reduce misperceptions
   • Reorient a confused client; one-to-one observation for DTs
   • Give thiamine before glucose; replace fluids and electrolytes
3. Safety of client and others
   • Stimulant psychosis (paranoia, hallucinations): calm, nonthreatening approach, space, de-escalation
   • Suicide risk screening, especially during stimulant crash and early recovery
4. Therapeutic relationship
   • Nonjudgmental, empathic, honest; avoid blaming or moralizing
   • Respond to anxiety or wish to leave with open, exploring statements ("You seem worried about being here. Tell me what's going on for you.")
   • Confront denial gently with facts; use motivational interviewing
5. Relapse prevention
   • Help the client identify triggers (people, places, emotions) and plan coping strategies
   • Teach refusal skills, stress management, and alternatives such as deep breathing or a short walk for nicotine craving
6. Nutrition and cognition
   • Balanced diet, vitamins; for Korsakoff syndrome, repeat information, keep simple routines, use memory aids, and ensure safety
7. Family — discuss codependency and enabling; refer to Al-Anon, Nar-Anon, or Alateen

• Addiction is a treatable chronic illness; relapse is common and signals a need to adjust treatment, not failure
• Never stop alcohol or benzodiazepines abruptly on your own after heavy daily use — seek medically supervised withdrawal
• Disulfiram: avoid all alcohol, including hidden sources; the reaction can be severe
• Buprenorphine: dissolve under the tongue; do not combine with alcohol, benzodiazepines, or other sedatives; store locked away from children
• Carry naloxone and teach family how to use it; never use alone; fentanyl test strips reduce risk
• Tolerance falls quickly after detoxification, jail, or hospitalization — returning to the previous dose can be fatal
• Avoid sharing needles; use syringe services; get tested and vaccinated for hepatitis B
• Join a mutual-help group and keep follow-up visits

• SUD: 2 or more of 11 criteria in 12 months; mild 2–3, moderate 4–5, severe 6 or more
• Alcohol withdrawal: seizures 12–48 h; DTs 48–96 h, early sign disorientation and confusion; monitor pulse and BP
• Benzodiazepines treat alcohol withdrawal; dose by CIWA-Ar
• Thiamine before glucose to prevent Wernicke encephalopathy
• Opioid overdose → pinpoint pupils, respiratory depression → naloxone, repeat as needed; OTC naloxone since 2023
• Opioid withdrawal → rhinorrhea, lacrimation, yawning, dilated pupils, diarrhea — rarely fatal
• Buprenorphine: start in moderate withdrawal; X-waiver eliminated 2023
• Naltrexone requires 7–10 days opioid-free; disulfiram → avoid hidden alcohol
• Cocaine → tachycardia, hypertension; methamphetamine → paranoia and hallucinations
• Korsakoff → amnesia with confabulation; use repetition and simple routines
• Nonjudgmental attitude; relapse prevention = identify triggers and coping strategies