naloxone
Brands: Narcan
Last reviewed 2025-12-31
Reviewed by PsychMed Editorial Team.
Quick answers
What is naloxone?
Naloxone (brand Narcan and others) is an opioid receptor antagonist used for the emergency treatment of known or suspected opioid overdose, as manifested by respiratory and/or central nervous system depression (label).
What is Narcan?
Narcan is a brand name for naloxone.
What is Narcan (naloxone) used for?
Label indications include: Emergency treatment of known or suspected opioid overdose (label).
What drug class is Narcan (naloxone)?
Opioid receptor antagonist used for the emergency treatment of known or suspected opioid overdose (respiratory and/or CNS depression). Because naloxone’s duration is often shorter than the opioid involved, repeat dosing and emergency medical evaluation are commonly required (label/guideline).
What strengths does Narcan (naloxone) come in?
Intranasal spray devices (e.g., Narcan 4 mg) (label).
Snapshot
- Class: Adjunctive therapy
- Common US brands: Narcan
- Therapeutic drug monitoring not routinely recommended.
- Last reviewed: 2025-12-31
Clinical Highlights
Naloxone (brand Narcan and others) is an opioid receptor antagonist used for the emergency treatment of known or suspected opioid overdose, as manifested by respiratory and/or central nervous system depression (label). Naloxone is an emergency rescue medication, not a substitute for medical care. Product labeling emphasizes seeking emergency medical assistance after the first dose and keeping the person under continued surveillance until help arrives (label).
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- Because naloxone’s duration can be shorter than the opioid involved, relapse into respiratory depression can occur. Labeling describes repeat dosing every 2–3 minutes if the person does not respond or responds and then relapses (label).
- Rapid opioid reversal can trigger precipitated withdrawal in people who are physically dependent on opioids; this can include agitation, vomiting, diarrhea, and sympathetic symptoms (label/clinical).
- Take-home naloxone distribution is commonly incorporated into harm reduction and OUD care and other high-risk settings, and systematic reviews support its effectiveness in reducing overdose deaths at a population level (review/guideline).
- The compare view, naloxone evidence feed, and naloxone print page support counseling when overdose prevention is discussed alongside OUD treatment planning.
Dosing & Formulations
Intranasal naloxone is commonly supplied as a single-use nasal spray device (for example, Narcan 4 mg). Injectable formulations also exist (label/clinical). Narcan nasal spray labeling recommends one spray into one nostril as the initial dose, followed by repeat doses every 2–3 minutes (using a new device) if the person does not respond or responds then relapses (label).
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- Labeling recommends alternating nostrils with each repeat dose (label).
- Reversal of respiratory depression from partial agonists (e.g., buprenorphine) may be incomplete and can require repeated dosing (label).
Monitoring & Risks
The core safety risk is re-sedation/recurrence when the opioid lasts longer than naloxone; continued observation and repeated dosing may be needed until emergency help is available (label/clinical). Precipitated withdrawal can be severe in opioid-dependent patients and may include agitation, vomiting, diarrhea, tachycardia, and hypertension; clinicians often plan for aspiration and safety risks during reversal (label/clinical).
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- Naloxone can restore breathing but does not prevent subsequent overdose if opioids are re-used; overdose prevention counseling is typically paired with OUD treatment engagement (guideline/clinical).
Drug Interactions
Naloxone reverses opioid agonist effects and will reduce opioid analgesia; this is an intended pharmacologic effect rather than a traditional “interaction” (label/clinical). If opioids are given for pain after naloxone reversal, careful clinical monitoring is required because opioid effects can re-emerge as naloxone wears off (clinical).
Practice Notes
Many OUD guidelines and clinical protocols encourage naloxone access for patients and households, especially when relapse risk is present or opioids (including methadone or buprenorphine) are part of care (guideline/clinical). Practical counseling often includes device storage, checking expiration, and training close contacts on recognition of overdose signs and repeat dosing while awaiting emergency services (label/clinical).
References
- NARCAN (naloxone hydrochloride) nasal spray prescribing information — DailyMed (2025)
- Naloxone hydrochloride injection prescribing information — DailyMed (2024)
- ARE Take Home Naloxone Programmes Effective? Systematic Review Utilizing Application OF THE Bradford Hill Criteria — Addiction (2016)
- TIP 63: Medications for Opioid Use Disorder — SAMHSA (2021)