Opioid overdose is a life-threatening toxicologic emergency characterized by CNS depression, respiratory depression progressing to respiratory arrest, and ultimately cardiac arrest if untreated. [1] The sine qua non is respiratory depression, and the mainstay of emergency management is airway support and naloxone administration. [2]
The following decision tree from Boyer (NEJM) illustrates the management algorithm for opioid analgesic overdose in adults:
1. History
- What substance was used? (heroin, fentanyl, prescription opioids, methadone, unknown pills)
- Route of administration (IV, intranasal, oral, transdermal)
- Time of last use and estimated amount
- Intentional vs. unintentional ingestion — assess for suicidality
- Coingestions: alcohol, benzodiazepines, stimulants, acetaminophen-containing products [2]
- Prior naloxone administration by bystanders or EMS (dose, route, response)
- Duration of unresponsiveness (risk of rhabdomyolysis, compartment syndrome, aspiration) [2]
- History of opioid tolerance or recent abstinence (incarceration, detox, rehab) [3]
2. Alarm Features
- Respiratory rate <12/min or apnea — the defining feature of opioid toxicity [2]
- Cyanosis (lips, fingertips) [4]
- Unresponsiveness to verbal/physical stimuli
- Pulselessness or cardiac arrest
- Pulmonary edema (crackles, frothy sputum) — can develop acutely or after naloxone reversal [2][5]
- Chest wall rigidity ("wooden chest syndrome") — particularly with IV fentanyl [6]
- Hypothermia from prolonged down time [2]
- Compartment syndrome from prolonged immobility [2]
3. Medications
Naloxone (primary reversal agent)
- IV/IO/IM: 0.4 mg–2 mg, repeat every 2–3 minutes as needed [7-8]
- Intranasal: 4 mg spray into one nostril; repeat in other nostril after 2–3 minutes if no response [7]
- Goal: restore RR >10/min while minimizing precipitated withdrawal [7]
- Duration of action: 30–90 minutes — shorter than most opioids; monitor for resedation [9]
- If no response after 10 mg total, question the diagnosis of opioid overdose [2]
- High-dose formulations (8 mg, 10 mg IN) are associated with more severe precipitated withdrawal without survival benefit [7]
Nalmefene: Longer-acting opioid antagonist; available by prescription; less clinical data than naloxone [1]
Naloxone infusion: Two-thirds of the effective bolus dose per hour for recurrent respiratory depression [2]
Medications to avoid: Flumazenil should not be given empirically in polysubstance overdose (seizure risk in benzodiazepine-dependent patients)
4. Diet
- Not directly applicable in the acute setting
- NPO if airway is compromised or intubation is anticipated
- Post-recovery: assess nutritional status in patients with opioid use disorder; many are malnourished
5. Review of Systems
- Neurologic: Level of consciousness, last known normal, seizure activity
- Respiratory: Snoring/gurgling, dyspnea, cough (aspiration, pulmonary edema)
- Cardiac: Chest pain, palpitations (consider coingestion or hypoxic cardiac injury)
- GI: Nausea/vomiting (aspiration risk), abdominal pain (body packing)
- Musculoskeletal: Extremity pain, swelling (compartment syndrome from prolonged immobility) [2]
- Psychiatric: Suicidal ideation, depression, prior self-harm
6. Collateral History and Family History
- Bystanders/EMS: scene findings (drug paraphernalia, pill bottles, fentanyl patches, empty containers)
- Pharmacy records and prescription drug monitoring program (PDMP)
- Family/friends: known substance use, recent relapse, recent discharge from rehab or incarceration
- Family history of substance use disorder, psychiatric illness
- Social context: housing instability, isolation (no one to call for help), access to naloxone [7]
7. Risk Factors
Per AHA and published literature, major risk factors include: [3]
- Male sex, age 25–55 years
- History of opioid use disorder or prior overdose (strongest predictor of future overdose) [10]
- Recent period of abstinence with loss of tolerance (post-incarceration, post-detox)
- High-dose opioid prescriptions (≥90 MME/day) [10]
- Concurrent use of benzodiazepines, alcohol, or other CNS depressants [3]
- IV drug use
- Use of illicitly manufactured fentanyl or fentanyl analogues [11]
- Comorbid psychiatric disorders (depression, suicidality) [3]
- Respiratory disease (COPD, sleep apnea)
- Using alone without a bystander
8. Differential Diagnosis
- Polysubstance overdose (benzodiazepines, alcohol, GHB, barbiturates) — miosis and coma may be present, but profound respiratory depression is more specific to opioids [2]
- Hypoglycemia — altered mental status, but typically no respiratory depression; check glucose immediately
- Stroke/intracranial hemorrhage — focal neurologic deficits, asymmetric pupils
- Postictal state — history of seizure, tongue bite, incontinence
- Sepsis/meningitis — fever, hemodynamic instability
- Carbon monoxide poisoning — altered mental status, cherry-red skin
- Clonidine/alpha-2 agonist overdose (including xylazine) — miosis, bradycardia, hypotension; will not respond to naloxone [12]
- Antipsychotic or sedative-hypnotic overdose — miosis and coma possible, but respiratory depression is usually less prominent [2]
Pearl: If the patient does not respond to naloxone (up to 10 mg), strongly reconsider the diagnosis. [2]
9. Past Medical History
- Prior overdose events (number, substances, naloxone use)
- Opioid use disorder — current treatment (methadone, buprenorphine)?
- Chronic pain conditions and current opioid prescriptions
- Psychiatric history (depression, PTSD, prior suicide attempts)
- Hepatitis B/C, HIV status
- Endocarditis, DVT/PE, skin/soft tissue infections (IVDU complications)
- Prior intubations or ICU admissions
10. Physical Exam
Vital signs
- RR <12/min (hallmark finding) [2]
- Bradycardia, hypotension [6]
- Hypothermia (prolonged down time) [2]
- SpO₂ <90%
Focused exam
- Pupils: Miosis (pinpoint) — classic but not always present; mydriasis may occur with severe hypoxia or meperidine/tramadol [2]
- Airway: Snoring, gurgling, airway obstruction
- Lungs: Crackles (pulmonary edema), decreased breath sounds (aspiration)
- Skin: Cyanosis, needle track marks, cold/clammy skin; search thoroughly for fentanyl patches (axillae, perineum, scrotum, oropharynx) [2]
- Extremities: Compartment syndrome — tense, swollen muscle groups in patients found down for prolonged periods [2]
- GCS: Document and trend
11. Lab Studies
- Fingerstick glucose — immediate, rule out hypoglycemia
- Acetaminophen level — critical in all overdose patients; coformulated opioid-acetaminophen products are commonly misused [2]
- ABG/VBG — respiratory acidosis (elevated pCO₂), metabolic acidosis (lactic acidosis from hypoperfusion)
- Serum lactate — ≥5.0 mmol/L is a strong predictor of mortality in drug overdose [13]
- BMP — electrolytes, renal function (rhabdomyolysis, AKI)
- CK — if prolonged immobility suspected (compartment syndrome, rhabdomyolysis)
- Troponin — elevated troponin on admission is a strong risk factor for death (OR 21.1) [13]
- Salicylate level — consider in unknown ingestion
- Ethanol level
- Urine drug screen — rarely changes acute management; standard screens miss fentanyl, methadone, and many synthetic opioids [2]
- LFTs — if acetaminophen coingestion suspected
- Coagulation studies — if hepatotoxicity or DIC suspected
12. Imaging
- Chest X-ray: Indicated if hypoxia persists after naloxone reversal — evaluate for aspiration pneumonitis, noncardiogenic pulmonary edema [2]
- CT head: If altered mental status does not improve with naloxone, or if focal neurologic deficits are present — rule out stroke, intracranial hemorrhage
- Abdominal imaging (CT or KUB): If body packing/stuffing is suspected
- Imaging is not routinely necessary in straightforward opioid overdose that responds to naloxone
13. Special Tests
- Poison Control Center consultation (1-800-222-1222) — recommended for complex or unknown ingestions
- Compartment pressure measurement — if clinical suspicion of compartment syndrome [2]
- Point-of-care ultrasound (POCUS): Cardiac function, IVC assessment, lung sliding (pneumothorax vs. pulmonary edema)
- Fentanyl test strips — community-level harm reduction tool, not used in ED diagnostics [7]
14. ECG
- Obtain ECG in all admitted patients and those with suspected polysubstance ingestion [13-14]
- QTc prolongation: Methadone is a well-known cause; QT prolongation is an independent risk factor for cardiovascular events in overdose (OR 27.6) [13]
- Bradycardia/sinus bradycardia: Common with opioid toxicity
- ST changes: Hypoxia-related demand ischemia; NSTEMI is more common than STEMI in opioid overdose [15]
- Arrhythmias: Torsades de pointes (methadone), VF in cardiac arrest [13]
- Wide QRS: Consider coingestion (tricyclic antidepressants, sodium channel blockers)
15. Assessment
Opioid overdose is a clinical diagnosis based on the triad of respiratory depression, CNS depression, and miosis in the context of known or suspected opioid exposure. [2] The diagnosis is confirmed by response to naloxone. Key assessment points:
- Severity stratification: Respiratory depression alone vs. respiratory arrest vs. cardiac arrest — each requires escalating interventions [1]
- Most opioid deaths involve polysubstance use — benzodiazepines, alcohol, and xylazine are common coingestants that may blunt naloxone response [1][12]
- Fentanyl-era considerations: Illicitly manufactured fentanyl dominates the current epidemic; onset is rapid, and higher or repeated naloxone doses may be needed [7][11]
- Complications to anticipate: Aspiration pneumonitis, noncardiogenic pulmonary edema, rhabdomyolysis, compartment syndrome, AKI, hypoxic brain injury, toxic leukoencephalopathy (can present days to weeks later) [6][13]
16. Treatment Plan
Initial stabilization (ABCs first — per AHA 2025 Guidelines): [1][16]
- Airway: Head tilt–chin lift or jaw thrust; suction; check for obstructing objects and fentanyl patches in oropharynx
- Breathing: Bag-valve mask ventilation if RR <10/min or apnea; supplemental O₂
- Circulation: If pulseless → standard CPR with compressions and ventilations; do not delay CPR for naloxone [1]
Naloxone administration: [7-8]
- IV/IM: 0.4–2 mg; repeat every 2–3 minutes (AHA recommends up to 2–4 mg IN or 0.2–2 mg IV/IO/IM) [7]
- Intranasal: 4 mg in one nostril; repeat in other nostril after 2–3 minutes
- Titrate to RR >10/min — avoid full reversal in opioid-dependent patients to minimize precipitated withdrawal
- If requiring repeated boluses → naloxone infusion at two-thirds of effective bolus dose per hour [2]
If no response to naloxone
- Reassess diagnosis; consider non-opioid causes or coingestants
- Proceed with intubation and mechanical ventilation if needed [2]
Precipitated withdrawal management
- Supportive care: IV fluids, antiemetics (ondansetron), clonidine for sympathetic symptoms
- Reassurance and calm environment [7]
Post-stabilization
- Evaluate and treat for OUD: initiate buprenorphine or arrange methadone — treatment after overdose is associated with reduced all-cause and opioid-related mortality [10]
- Prescribe or provide take-home naloxone to patient and family [7][17]
- Social work/addiction medicine consultation
17. Disposition
Admit to ICU if: [2]
- Intubated or requiring naloxone infusion
- Long-acting or extended-release opioid ingestion (methadone, sustained-release formulations)
- Recurrent respiratory depression despite naloxone
- Pulmonary edema, hemodynamic instability, or cardiac arrest
Observation (4–6 hours minimum): [1-2]
- Patients who respond to naloxone for short-acting opioids (heroin, fentanyl, morphine)
- Recurrent respiratory depression occurred in 72% of patients treated with titrated low-dose IV naloxone in one study — vigilant monitoring is essential [1]
Discharge criteria
- Fully awake and alert with normal vital signs for ≥1 hour after last naloxone dose [2]
- No recurrent respiratory depression
- Ambulatory, tolerating PO
- Safe disposition plan (not leaving alone)
- Naloxone prescribed/provided at discharge
Specialist consultation triggers
- Toxicology/Poison Control for complex or unknown ingestions
- Psychiatry if intentional overdose/suicidal ideation
- Addiction medicine for OUD treatment initiation
18. Follow Up / Return Precautions
- Follow-up within 1–3 days with PCP or addiction medicine for OUD treatment initiation/continuation [10]
- Naloxone education for patient and close contacts — ensure they have naloxone at home [7][17]
- Return immediately for: recurrent drowsiness, difficulty breathing, chest pain, vomiting, confusion, or any worsening symptoms
- Expected course: Naloxone wears off in 30–90 minutes; if the opioid outlasts naloxone, resedation can occur — this is why ED observation is critical [9]
- Harm reduction counseling: Use with someone present, start with small test doses, avoid mixing with benzodiazepines/alcohol, use fentanyl test strips [7]
- Previous overdose is the strongest predictor of future overdose — emphasize linkage to OUD treatment (buprenorphine or methadone), which reduces all-cause and opioid-related mortality [10]
References
1. Part 10: Adult and Pediatric Special Circumstances of Resuscitation: 2025 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. — Cao D, Arens AM, Chow SL, et al. Circulation. 2025.
2. Management of Opioid Analgesic Overdose. — Boyer EW. The New England Journal of Medicine. 2012.
3. Management of Opioid Use Disorder in the USA: Present Status and Future Directions. — Blanco C, Volkow ND. Lancet. 2019.
4. Naloxone and Buprenorphine Treatment for Adolescent Opioid Overdose and Opioid Use Disorder. — Ball A, Buresh C, Hadland SE. JAMA Pediatrics. 2026.
5. 2023 American Heart Association Focused Update on the Management of Patients With Cardiac Arrest or Life-Threatening Toxicity Due to Poisoning: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. — Lavonas EJ, Akpunonu PD, Arens AM, et al. Circulation. 2023.
6. FDA Drug Label. — Updated date: 2026-01-31. Food and Drug Administration.
7. Medications for Opioid Use Disorder, Opioid Withdrawal, and Opioid Overdose. — Harris MTH, Weinstein ZM, Walley AY. The Journal of the American Medical Association. 2026.
8. FDA Drug Label. — Updated date: 2025-07-31. Food and Drug Administration.
9. Prevention of Opioid Overdose. — Babu KM, Brent J, Juurlink DN. The New England Journal of Medicine. 2019.
10. CDC Clinical Practice Guideline for Prescribing Opioids for Pain - United States, 2022. — Dowell D, Ragan KR, Jones CM, Baldwin GT, Chou R. MMWR. Recommendations and Reports : Morbidity and Mortality Weekly Report. Recommendations and Reports. 2022.
11. Abuse of Fentanyl: An Emerging Problem to Face. — Kuczyńska K, Grzonkowski P, Kacprzak Ł, Zawilska JB. Forensic Science International. 2018.
12. Brain Oxygen Responses Induced by Opioids: Focus on Heroin, Fentanyl, and Their Adulterants. — Kiyatkin EA, Choi S. Frontiers in Psychiatry. 2023.
13. Opioid-Associated Out-of-Hospital Cardiac Arrest: Distinctive Clinical Features and Implications for Health Care and Public Responses: A Scientific Statement From the American Heart Association. — Dezfulian C, Orkin AM, Maron BA, et al. Circulation. 2021.
14. Acute Medication Poisoning. — Vega IL, Griswold MK, Laskey D. American Family Physician. 2024.
15. Cardiovascular Complications of Opioid Use: JACC State-of-the-Art Review. — Krantz MJ, Palmer RB, Haigney MCP. Journal of the American College of Cardiology. 2021.
16. Part 1: Executive Summary: 2025 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. — Del Rios M, Bartos JA, Panchal AR, et al. Circulation. 2025.
17. Medications to Treat Opioid Use Disorder. — Walter K. The Journal of the American Medical Association. 2026.