What is the recommended dose of Narcan (naloxone) for reversing opioid overdose?

Recommended Dose of Naloxone (Narcan) for Opioid Overdose

For adults with suspected opioid overdose, administer an initial dose of 0.4 to 2 mg naloxone intravenously, repeated every 2-3 minutes as needed, or 2 mg intramuscularly/intranasally if IV access is unavailable, with lower starting doses (0.04-0.4 mg) reserved for known opioid-dependent patients to minimize withdrawal. 1

Initial Dose Selection by Route

Intravenous Administration (First-Line if Access Available)

• Standard dose: 0.4 to 2 mg IV, repeated at 2-3 minute intervals if inadequate response 1, 2
• Opioid-dependent patients: Start with 0.04 to 0.4 mg IV to avoid precipitating severe withdrawal, then titrate up to 2 mg if needed 1
• If no response after 10 mg total, question the diagnosis of opioid toxicity 2

Intramuscular Administration (When IV Unavailable)

• 2 mg IM, repeated in 3-5 minutes if necessary 1
• IM administration produces longer-lasting effects than IV 2

Intranasal Administration (Community/Lay Responder Use)

• 2 mg intranasal (using 4 mg formulation delivers approximately 2 mg absorbed due to ~50% bioavailability), repeated in 3-5 minutes 1, 3
• Higher-concentration intranasal formulations (2 mg/mL) have similar efficacy to IM administration 4
• Multiple doses are frequently needed: 78% of real-world overdoses required ≥2 doses, and 30% required ≥3 doses 5

Pediatric Dosing

• Initial dose: 0.01 mg/kg IV, IM, or subcutaneous 6, 2
• If inadequate response: 0.1 mg/kg may be administered 6
• Alternative weight-based dosing: <20 kg or <5 years: 0.1 mg/kg; ≥20 kg or ≥5 years: 2 mg 6
• Do NOT administer to newborns of mothers with chronic opioid use due to seizure risk and acute withdrawal 6

Critical Management Priorities (Before and During Naloxone Use)

Airway Management Takes Absolute Priority

• Provide bag-mask ventilation FIRST before administering naloxone 1
• Standard resuscitative measures must not be delayed while preparing naloxone 1

Cardiac Arrest vs. Respiratory Arrest

• Cardiac arrest: Focus on high-quality CPR; naloxone has no proven benefit and should not delay resuscitation 1
• Respiratory arrest with pulse present: Administer naloxone alongside standard BLS/ACLS care 1, 6

Titration Strategy to Minimize Withdrawal

The goal is restoration of adequate breathing, NOT full consciousness 3, 7

• Use the lowest effective dose to minimize withdrawal symptoms 1
• Titrate in small increments (0.04-0.1 mg) for opioid-dependent patients 7
• Excessive doses cause significant analgesia reversal, hypertension, nausea, vomiting, sweating, agitation, and circulatory stress 1
• Withdrawal symptoms include tachycardia, hypertension, piloerection, vomiting, agitation, and drug cravings 1

Post-Administration Monitoring (Critical)

Duration of Action Concerns

• Naloxone duration: 45-70 minutes (some sources report 30-60 minutes), often shorter than opioid effects 1, 3
• Observe patients for at least 2 hours after the last naloxone dose for recurrence of respiratory depression 6
• Extended observation required for long-acting opioids (methadone, sustained-release formulations, fentanyl) 1

Recurrent Toxicity Management

• Repeated small doses or continuous infusion may be needed if respiratory depression recurs 1, 6
• Standard infusion: 2 mg naloxone in 500 mL normal saline or D5W (concentration 0.004 mg/mL) 1, 2
• Infusion rate titrated to maintain adequate respiratory function without complete reversal 6

Special Considerations for Synthetic Opioids

• Fentanyl and analogues likely require higher total doses of naloxone compared to heroin 3
• Real-world data shows 78% of overdoses required multiple administrations, with 30% needing ≥3 doses in the era of illicitly manufactured fentanyl 5
• Take-home kits should include at least two doses to ensure adequate supply 3, 8

Common Pitfalls to Avoid

• Delaying ventilation while waiting for naloxone effect 1
• Premature discharge after successful reversal - recurrent depression is common 1
• Using excessive doses in opioid-dependent patients - precipitates severe withdrawal without improving outcomes 1, 8
• Assuming naloxone will reverse non-opioid respiratory depression - it will NOT reverse benzodiazepine or other non-opioid drug effects 1
• Failing to recognize mixed overdoses requiring additional interventions 1

Postoperative Setting (Different Approach)

• Much smaller doses: 0.1 to 0.2 mg IV increments every 2-3 minutes 2
• Goal is adequate ventilation without reversing analgesia 2
• In pediatrics: 0.005 to 0.01 mg IV increments 2