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

Recommended Naloxone Dose for Suspected Opioid Overdose

For adults with suspected opioid overdose and respiratory depression (but not in cardiac arrest), administer an initial dose of 0.4 to 2 mg naloxone intravenously, with the option to start at lower doses (0.04 to 0.4 mg) in opioid-dependent individuals to minimize withdrawal symptoms, repeating or escalating to 2 mg every 2-3 minutes if inadequate response. 1, 2

Initial Dose Selection

Adult Dosing:

• Standard initial dose: 0.4 to 2 mg IV for known or suspected opioid overdose 2
• Lower initial dose: 0.04 to 0.4 mg should be considered in opioid-dependent patients to avoid precipitating severe withdrawal (agitation, hypertension, violent behavior) 1, 3
• If no response after 10 mg total naloxone administered, question the diagnosis of opioid toxicity 2

Pediatric Dosing:

• Initial dose: 0.01 mg/kg IV 2
• If inadequate response, subsequent dose of 0.1 mg/kg may be administered 2

Neonatal Dosing:

• 0.01 mg/kg IV, IM, or subcutaneous 2

Route of Administration Priority

The evidence supports multiple effective routes, with selection based on clinical circumstances:

Intravenous (IV) - Preferred when available:

• Fastest onset of action and allows for precise dose titration 2, 4
• Recommended in emergency situations 2

Intranasal (IN) - Equally effective alternative:

• 2 mg dose, repeated in 3-5 minutes if necessary 3
• Higher-concentration intranasal formulations (2 mg/mL) have similar efficacy to intramuscular naloxone 5
• Slightly longer onset of action compared to IV/IM (mean difference 0.63 standardized units) 6
• May require rescue dosing 2.17 times more often than injectable routes 6
• Reduces needle-stick exposure risk for providers 7

Intramuscular (IM) - When IV unavailable:

• 2 mg dose, repeated in 3-5 minutes if necessary 3
• Slower onset than IV but effective 2
• Disfavored compared to IV due to difficulty with titration and slower clinical effect 4

Repeat Dosing Algorithm

If inadequate response after initial dose:

• Repeat dosing at 2-3 minute intervals 1, 2
• Continue escalating dose up to 2 mg per administration 1
• Some patients may require much higher total doses for atypical opioids (propoxyphene) or massive overdoses 1
• With synthetic opioids like fentanyl, multiple administrations are frequently needed (78% of real-world overdoses required ≥2 doses, 30% required ≥3 doses) 8

Critical Management Priorities

Airway and breathing support takes precedence:

• Provide bag-mask ventilation FIRST before naloxone administration 1, 3
• 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

Post-Administration Monitoring

Observation requirements:

• Naloxone duration of action is 45-70 minutes (or 30-60 minutes per some sources), often shorter than opioid effects 1
• Patients must be observed in healthcare setting until risk of recurrent toxicity is low and vital signs normalized 1, 3
• Longer observation needed for long-acting opioids (methadone, sustained-release formulations) 1

Managing recurrent toxicity:

• Administer repeated small doses or continuous infusion if respiratory depression recurs 1, 3
• Infusion preparation: 2 mg naloxone in 500 mL normal saline or D5W (concentration 0.004 mg/mL), titrated to patient response 2

Common Pitfalls to Avoid

Withdrawal precipitation:

• Excessive doses cause significant reversal of analgesia, hypertension, nausea, vomiting, sweating, agitation, and circulatory stress 1, 2
• Use lowest effective dose to minimize these effects 3

Premature discharge:

• Never discharge patients immediately after successful reversal—recurrent depression is common 1, 3

Delayed resuscitation:

• Do not delay standard CPR or airway management while waiting for naloxone effect 3

Misdiagnosis:

• Naloxone is ineffective for benzodiazepines and other non-opioid CNS depressants—recognize mixed overdoses 3
• If no response after 10 mg, strongly reconsider opioid toxicity diagnosis 2