Educational use only. Drug cards are AI-assisted study material for NCLEX preparation.
Mechanism of action
Pure mu-opioid receptor antagonist with high affinity — displaces opioids from the receptor, reversing respiratory depression and sedation within minutes. Has no agonist activity, so it cannot cause respiratory depression itself. Half-life is shorter than most opioids — re-narcotization (return of opioid effect) is the central monitoring concern.
Adverse effects
Life-threatening / NCLEX-tested
- Acute opioid withdrawal — severe agitation, hypertension, tachycardia, vomiting, sweating, piloerection in opioid-dependent patients (especially babies of opioid-using mothers)
- Pulmonary edema (uncommon, more often reported in surgical reversal scenarios)
- Severe hypertension and tachyarrhythmia, with rare reports of MI in patients with cardiac disease
- Seizures (rare, in mixed overdoses)
- Re-narcotization once naloxone wears off — recurrence of respiratory depression
Side effects
Common — what to teach
- Nausea, vomiting
- Sweating
- Trembling
- Headache
- Anxiety, agitation
- Mild flushing
Food & drug interactions
Generally minimal. Reverses ALL opioids — including buprenorphine (partial agonist; naloxone may displace it but high doses may be needed) and methadone (very long half-life — patient needs prolonged monitoring after reversal). Reverses opioid-induced histamine effects and ileus.
Nursing implications
Assessment, monitoring, patient teaching
- Indication: respiratory depression (RR < 12) and/or unresponsiveness with suspected opioid involvement
- Routes/doses: IM 0.4 mg, intranasal 4 mg or 8 mg sprays, IV 0.04–0.4 mg titrated; repeat every 2–3 minutes as needed
- Titrate to respiratory rate (≥ 12) and adequate ventilation, NOT to full alertness — overshooting causes severe withdrawal in dependent patients
- MONITOR for re-narcotization for at least 2 hours after the last dose (longer for long-acting opioids like methadone, sustained-release oxycodone, fentanyl patches) — naloxone can wear off before the opioid does
- Always continue rescue breathing/ventilation while naloxone takes effect
- Take-home naloxone: counsel families on every opioid prescription; teach the steps — call 911, give naloxone, rescue breaths, recovery position
- Newborns of opioid-using mothers: AVOID naloxone — precipitates severe neonatal withdrawal; treat respiratory depression with ventilation
When to hold / contraindications
- Newborns of opioid-using mothers (use ventilation instead)
- Suspected non-opioid cause of respiratory depression — may waste time
- Hypersensitivity to naloxone (rare)
- Note: there is no clinical reason to "hold" naloxone in active opioid overdose — give it; the question is dose and route
Memory anchor
"Narcan reverses, then wears off." Watch at least 2 hours; longer for methadone or fentanyl patches. Titrate to RR ≥ 12, not to full alertness — overshoot causes withdrawal.
Practice Naloxone questions
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