What is the dosing for Narcan (naloxone) in an adult or adolescent patient with an opioid overdose?

Naloxone Dosing for Opioid Overdose

For adults and adolescents 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 (0.04-0.4 mg) preferred in known opioid-dependent patients to minimize precipitated withdrawal while still reversing life-threatening respiratory depression. 1, 2

Initial Dose Selection and Route

The American Heart Association recommends starting with 0.4-2 mg IV as the standard initial dose for suspected opioid overdose. 1 However, the FDA label specifies this same range (0.4-2 mg) can be given intravenously, intramuscularly, or subcutaneously, with IV administration providing the most rapid onset. 2

Dose Titration Strategy for Opioid-Dependent Patients

• In patients with known opioid dependence, start with lower doses (0.04-0.4 mg IV) to avoid precipitating severe acute withdrawal syndrome while still achieving adequate respiratory reversal. 1, 3
• The goal is restoration of adequate ventilation and respiratory effort, not full consciousness or complete opioid reversal. 4
• If inadequate response occurs, repeat or escalate doses up to 2 mg every 2-3 minutes until respiratory function improves. 1, 2

Alternative Routes When IV Access Unavailable

• Intramuscular (IM): 2 mg, repeated in 3-5 minutes if necessary. 1
• Intranasal (IN): 2 mg (typically one 4 mg spray device), repeated in 3-5 minutes if necessary. 1
• Intranasal bioavailability is approximately 50% with slower uptake (mean time to peak 15-30 minutes) compared to IM administration. 5

Critical Management Priorities

Airway management with bag-mask ventilation must take absolute priority and should be initiated immediately while preparing naloxone—never delay ventilatory support waiting for naloxone to take effect. 1, 6

Clinical Algorithm

• Step 1: Begin bag-mask ventilation immediately for any patient with inadequate respirations. 1, 4
• Step 2: Administer initial naloxone dose (0.4-2 mg IV, or 0.04-0.4 mg in opioid-dependent patients). 1, 2
• Step 3: Repeat doses every 2-3 minutes if respiratory depression persists. 2
• Step 4: If no response after 10 mg total naloxone administered, question the diagnosis of opioid toxicity. 2
• Step 5: For cardiac arrest, focus on high-quality CPR—naloxone has no proven benefit in cardiac arrest and should not delay standard resuscitation. 1

Special Dosing Considerations

Pediatric Dosing

• Initial dose: 0.01 mg/kg IV, IM, or subcutaneous. 2
• If inadequate response, administer 0.1 mg/kg. 6, 2
• Alternative weight-based dosing: <5 years or <20 kg: 0.1 mg/kg; ≥5 years or ≥20 kg: 2 mg. 6

Continuous Infusion for Recurrent Depression

When respiratory depression recurs after initial bolus doses—particularly with long-acting opioids like methadone or fentanyl—transition to continuous naloxone infusion. 1, 4

• Standard preparation: 2 mg naloxone in 500 mL normal saline or D5W (concentration 0.004 mg/mL). 1, 2
• Titrate infusion rate to maintain adequate respiratory function without complete opioid reversal. 4, 6
• Mixtures must be used within 24 hours; discard unused solution after this time. 2

Post-Administration Monitoring

Naloxone's duration of action (45-70 minutes) is typically shorter than most opioids' respiratory depressant effects, requiring extended observation in a healthcare setting. 1, 5

Observation Requirements

• Minimum observation: At least 2 hours after the last naloxone dose for short-acting opioids. 1, 4
• Extended observation required for long-acting opioids (methadone, sustained-release formulations, fentanyl) as effects can persist well beyond naloxone's duration. 1, 4
• Monitor continuously for recurrent respiratory depression, which commonly occurs as naloxone wears off. 1, 7

Common Pitfalls to Avoid

Excessive Dosing Complications

• Using unnecessarily high doses precipitates acute withdrawal syndrome with hypertension, tachycardia, agitation, vomiting (with aspiration risk), piloerection, and drug cravings. 1, 7, 3
• Rapid or complete reversal can cause significant reversal of analgesia, nausea, vomiting, sweating, and circulatory stress. 1, 2
• In patients receiving therapeutic opioids for pain, excessive naloxone may cause catecholamine release leading to pulmonary edema and cardiac arrhythmias. 7

Recognition of Limitations

• Naloxone will NOT reverse respiratory depression from non-opioid drugs such as benzodiazepines, alcohol, or other sedatives—recognize mixed overdoses. 1, 4
• Premature discharge after successful reversal is dangerous; recurrent depression is common and potentially fatal. 1
• With highly potent synthetic opioids like fentanyl, multiple naloxone administrations are frequently required—real-world data shows 78% of overdose reversals required ≥2 doses and 30% required ≥3 doses. 8

Special Population Warnings

• Do NOT administer naloxone to newborns whose mothers have chronic opioid use due to risk of seizures and severe acute withdrawal. 6
• In patients with concurrent intracerebral hemorrhage, use the lowest effective dose (0.04-0.2 mg initially) and titrate slowly to avoid exacerbating bleeding through hypertensive crisis from precipitated withdrawal. 4