What is the recommended dose of Narcan (naloxone) for a patient experiencing an opioid overdose?

Naloxone Dosing for Opioid Overdose

For adults with suspected opioid overdose, administer an initial dose of 0.4 to 2 mg naloxone intravenously, repeating every 2-3 minutes as needed, with lower starting doses (0.04 to 0.4 mg) reserved for known opioid-dependent patients to minimize withdrawal symptoms. 1

Initial Dose Selection by Route

Intravenous Administration (Preferred)

• Start with 0.4 to 2 mg IV for most adults 1, 2
• For opioid-dependent individuals, consider starting at 0.04 to 0.4 mg IV to avoid precipitating severe withdrawal 1
• Repeat or escalate to 2 mg every 2-3 minutes if inadequate response 1
• If no response after 10 mg total, question the diagnosis of opioid toxicity 2

Intramuscular Administration

• 2 mg IM when IV access is unavailable 1
• Repeat in 3-5 minutes if necessary 1
• May produce longer-lasting effect than IV 2

Intranasal Administration

• 2 mg intranasal (viable alternative route) 1
• Repeat in 3-5 minutes if necessary 1
• Higher-concentration formulations (2 mg/mL) have similar efficacy to IM administration 3
• Nasal bioavailability is approximately 50% with slower uptake (mean time to peak 15-30 minutes) compared to IM 4

Pediatric Dosing

• Initial dose: 0.01 mg/kg IV for children 2
• If inadequate response, give subsequent dose of 0.1 mg/kg 2
• For neonates: 0.01 mg/kg IV, IM, or subcutaneous 2
• Do not administer to newborns whose mothers have long-term opioid use due to risk of seizures and acute withdrawal 5

Critical Management Priorities

Airway First, Naloxone Second

• Provide bag-mask ventilation BEFORE naloxone administration 1
• Airway management and breathing support take absolute precedence over medication 1, 6
• In cardiac arrest, focus on high-quality CPR—naloxone has no proven benefit and should not delay resuscitation 1
• For respiratory arrest with pulse present, administer naloxone alongside standard BLS/ACLS care 1

Titration Strategy

• Goal: restore adequate ventilation, NOT full consciousness 6, 4
• Titrate to respiratory rate ≥10 breaths/min while preserving analgesia 6
• Use the lowest effective dose to minimize withdrawal symptoms 1

Special Considerations for Synthetic Opioids

• Fentanyl overdoses likely require higher doses of naloxone 4
• Multiple naloxone administrations (MNA) frequently needed—78% of real-world overdose reversals required ≥2 doses, and 30% required ≥3 doses 7
• Over 90% of bystanders worried that one naloxone box may not be sufficient for successful reversal 7

Post-Administration Monitoring

Observation Duration

• Observe in healthcare setting until risk of recurrent toxicity is low and vital signs normalized 1, 6
• Naloxone duration of action is 45-70 minutes, often shorter than opioid effects 1, 4
• Minimum 2 hours observation after last naloxone dose 6
• Longer observation required for long-acting opioids (methadone, sustained-release formulations) 1, 6

Managing Recurrent Toxicity

• If recurrent depression occurs, administer repeated small doses or continuous infusion 1, 6
• Standard infusion: 2 mg naloxone in 500 mL normal saline (concentration 0.004 mg/mL), titrated to response 1, 2

Adverse Effects and Withdrawal Risk

Withdrawal Symptoms

• Naloxone has excellent safety profile in non-opioid-intoxicated patients 1
• In opioid-dependent patients, may precipitate: hypertension, tachycardia, piloerection, vomiting, agitation, drug cravings 1
• Excessive or rapid dosing causes significant analgesia reversal, hypertension, nausea, vomiting, sweating, circulatory stress 1, 2

Serious Risks

• Vomiting with aspiration risk is potentially life-threatening 8
• High-dose or rapidly infused naloxone may cause catecholamine release leading to pulmonary edema and cardiac arrhythmias 8

Common Pitfalls to Avoid

• Do not delay standard resuscitation while waiting for naloxone 1
• Do not discharge patients prematurely—recurrent toxicity can occur hours after initial response 1, 6
• Do not assume naloxone will reverse non-opioid respiratory depression (e.g., benzodiazepines) 1
• Do not use excessive doses—this precipitates severe withdrawal without improving outcomes 1
• Do not assume brief observation is adequate—formulation type dictates observation duration 6