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Opioid Use Disorder & Overdose

DSM-5-TR opioid use disorder with impaired control and risky use; overdose presents with respiratory depression, miosis, and coma requiring naloxone and airway support

Review date
reviewed 2026-05-04
Reading time
8 min read
Author
Dr Kola Tytler MBBS CertHE MBA MSt MRCGP
Psychiatry & Behavioral Sciencecommonlong-term-condition
On this page
Condition details
Psychiatry & Behavioral Science
common
8 min read
reviewed 2026-05-04
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About This Page

This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.

Key points

  • Overdose triad: respiratory depression, CNS depression, miosis
  • Treat overdose with airway/ventilation plus naloxone
  • Buprenorphine, methadone, and extended-release naltrexone reduce OUD morbidity/mortality
  • Start buprenorphine in moderate withdrawal to avoid precipitated withdrawal
  • Naltrexone requires complete detoxification and is contraindicated with current opioid use

Overview

Opioid use disorder is diagnosed by DSM-5-TR criteria over 12 months. Tolerance/withdrawal do not count when opioids are taken solely as prescribed. Overdose is immediately life-threatening because opioids suppress respiratory drive; fentanyl and sedative co-use increase risk.

Epidemiology

OUD is associated with overdose, infectious complications, trauma, suicide, chronic pain, incarceration, homelessness, and psychiatric comorbidity. Medications for OUD are central because they reduce mortality.

Clinical Features

Symptoms
Craving, inability to cut down, time spent using/recovering, role failure
Withdrawal: rhinorrhea, lacrimation, yawning, piloerection, diarrhea, myalgias
Overdose: somnolence/coma, bradypnea/apnea, cyanosis, pinpoint pupils
Injection complications: abscess, cellulitis, endocarditis, HIV/HCV
Suicidality, polysubstance use, pregnancy, repeated overdose
Signs
Intoxication: miosis, bradypnea, hypoxia, decreased bowel sounds, decreased consciousness
Withdrawal: mydriasis, yawning, lacrimation, piloerection, tachycardia, diarrhea
Track marks, skin infections, murmurs
Aspiration, pulmonary edema, trauma, rhabdomyolysis after overdose

Investigations

First-line
Overdose assessmentABCs, RR, O2 sat, glucose, mental status, trauma, co-ingestants
DSM-5-TR OUD assessmentSeverity, opioid type/route, fentanyl exposure, overdose, withdrawal, pain, pregnancy, comorbidity
Urine drug testingSupports planning; standard screens may miss fentanyl
Second-line
Infectious screeningHIV, HBV/HCV, STIs, pregnancy, vaccination/harm reduction
ECGMethadone, QT drugs, syncope, cardiac risk
COWSDetermines readiness for buprenorphine induction
Specialist
Emergency careRespiratory depression, recurrent sedation, long-acting opioids, polysubstance overdose, aspiration, trauma
Addiction medicine/OTPMethadone, complex induction, pregnancy, polysubstance use, repeated relapse

Management

SAMHSA TIP 63 and ASAM National Practice Guideline for Opioid Use Disorder
1
Overdose
  • Support airway and ventilation first
  • Naloxone IN/IM/IV; repeat every 2-3 minutes as needed
  • Observe for recurrent respiratory depression, especially methadone/ER opioids/polysubstance use
2
OUD medication
  • Buprenorphine/naloxone when moderate withdrawal is present
  • Methadone via OTP for high tolerance or unsuccessful buprenorphine; monitor sedation/QTc
  • Extended-release naltrexone after opioid-free period
3
Harm reduction
  • Take-home naloxone for patient and contacts
  • Avoid benzodiazepines/alcohol; counsel never using alone
  • Syringe services, HIV/HCV prevention, wound care, safer-use counseling

Complications

  • Fatal overdose:
  • Infective endocarditis:
  • HIV/HCV:
  • Neonatal opioid withdrawal syndrome:
  • Precipitated withdrawal:
  • Polysubstance overdose:
USMLE Step 2 CK Exam Tips
  • 1Overdose = ventilation + naloxone
  • 2Miosis + coma + bradypnea = naloxone
  • 3Buprenorphine too early precipitates withdrawal
  • 4Methadone prolongs QT and accumulates
  • 5Naltrexone requires opioid-free state
  • 6Pregnancy: methadone or buprenorphine maintenance

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Verified Sources & References

SAMHSA TIP 63: Medications for Opioid Use Disorder
ASAM National Practice Guideline for Opioid Use Disorder
APA DSM-5-TR Educational Resources
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