Naloxone (naloxone hydrochloride)
Also sold as: Nalone, Narcan, Nalox, Naloxone HCl
Pregnancy
Cat B
Lactation
Unknown
Schedule
H1
Forms
injection 0.4mg/mL (1mL ampoule — IV/IM/SC) +3
Indications
- Opioid overdose reversal — complete or partial reversal of opioid-induced respiratory depression, sedation, and hypotension (emergency use)
- Post-operative opioid reversal — reversal of residual opioid effects after surgery
- Neonatal opioid depression — reversal of respiratory depression in neonates exposed to maternal opioids during delivery
- Opioid-induced pruritus management (low-dose, naloxone infusion)
- Diagnostic tool — in patients with suspected opioid intoxication (response to naloxone confirms opioid as causative agent)
- Take-home naloxone — community-level distribution for opioid overdose prevention among opioid-dependent individuals and their families
Adult Dosing
Opioid overdose reversal — IV (preferred route)
0.4–2 mg IV
Repeat every 2–3 minutes if no response; total up to 10 mg
If no response after 10 mg, reassess opioid as the cause. Onset <2 minutes IV.
Opioid overdose reversal — IM or SC (when IV access unavailable)
0.4–2 mg IM or SC
Repeat every 2–3 minutes if no response
Onset 5–10 minutes (slower than IV). Use IV as soon as access is established.
Opioid overdose reversal — intranasal (Narcan nasal spray)
4 mg per nostril
May repeat in alternate nostril every 2–3 minutes if no response
Post-operative opioid reversal (titrated reversal)
0.04–0.1 mg IV increments every 2–3 minutes
Titrate carefully to reverse respiratory depression without causing acute pain
Do NOT give 0.4 mg bolus routinely post-operatively — causes acute pain, catecholamine surge, and risk of pulmonary edema.
Opioid-dependent patients (to minimise precipitated withdrawal)
0.04–0.1 mg IV; titrate in small increments
Repeat every 2–3 minutes, guided by respiratory rate and level of consciousness
Goal is to restore ventilation, not full reversal. Abrupt full reversal precipitates severe acute withdrawal.
Continuous infusion for long-acting opioids (methadone, fentanyl patch overdose)
2/3 of the effective reversal bolus dose per hour
Continuous IV infusion; titrate to maintain adequate ventilation
Duration of naloxone (30–90 min) is shorter than most opioids — re-sedation will occur without infusion.
Pediatric Dosing
Opioid overdose in child: 0.01 mg/kg IV first; if no response after 2 doses, escalate to 0.1 mg/kg.
Renal Dose Adjustment
| CrCl / eGFR | Dose Adjustment |
|---|---|
| Any | No dose adjustment required — naloxone is primarily metabolized in the liver (glucuronidation) and metabolites are renally excreted; clinical effect not significantly altered by renal function |
Hepatic Adjustment
No dose adjustment required. Hepatic disease may prolong duration of action slightly due to reduced clearance. Monitor for re-sedation.
Pregnancy & Lactation
Pregnancy: Category B
Category B. Use in life-threatening opioid overdose during pregnancy — maternal benefit clearly outweighs risk. May precipitate acute opioid withdrawal in opioid-dependent pregnant women, causing fetal distress (abrupt withdrawal changes placental blood flow). Use with care — goal is to restore maternal ventilation, not achieve full opioid reversal. Fetal monitoring required after use in pregnancy.
Lactation: Unknown
No data on naloxone excretion in human milk. Given very short half-life and poor oral bioavailability, any exposure to nursing infant through breast milk would be clinically insignificant. Emergency use is not contraindicated during breastfeeding.
Top Drug Interactions
| Interacting Drug | Effect | Severity |
|---|---|---|
| Opioid analgesics (morphine, fentanyl, oxycodone, codeine, tramadol) | Intentional antagonism — naloxone reverses all opioid effects (analgesia, sedation, respiratory depression). CRITICAL: Duration of naloxone action (30–90 minutes) is shorter than most opioids. Re-sedation may occur as naloxone wears off before the opioid — observe patient for at least 2 hours after last naloxone dose; repeated doses or continuous infusion may be needed. | Major |
| Buprenorphine (partial opioid agonist) | Buprenorphine has extremely high mu-receptor affinity — naloxone may not achieve complete reversal at standard doses. Very high naloxone doses (2–10mg IV) are required for full reversal of buprenorphine-induced respiratory depression. In Suboxone misuse (IV injection), the naloxone component precipitates withdrawal in opioid-dependent individuals (this is the intended abuse-deterrent mechanism). | Major |
| Methadone | Methadone has a very long half-life (24–36 hours). Naloxone reversal is brief — continuous naloxone infusion is usually required for methadone overdose. Titrate infusion to maintain adequate ventilation; acute withdrawal precipitation must be carefully managed. | Major |
| Cardiovascular drugs (antihypertensives) | Rapid opioid reversal releases catecholamines — causing acute hypertension, tachycardia, ventricular arrhythmias, and pulmonary edema in susceptible patients (cardiac disease, hypertension). Titrate reversal dose carefully; avoid bolus reversal in post-operative cardiac patients. | Moderate |
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Side Effects
Common
- Acute opioid withdrawal (in opioid-dependent patients) — agitation, nausea, vomiting, diaphoresis, piloerection, hypertension, tachycardia, abdominal cramps, diarrhea, myalgias
- Hypertension and tachycardia (catecholamine release during reversal)
- Nausea and vomiting
- Tremor
- Injection site reactions (IM/SC use)
Serious / Discontinue If
- Re-sedation and recurrent respiratory depression — CRITICAL. Naloxone duration (30–90 min) is shorter than most opioids. Monitor patient for at least 2 hours after last dose; re-dose or start infusion if opioid half-life exceeds naloxone duration.
- Pulmonary edema — acute non-cardiogenic pulmonary edema reported after rapid opioid reversal, especially in patients with cardiovascular disease. Use lowest effective dose; avoid rapid high-dose bolus in post-operative settings.
- Ventricular arrhythmias (tachycardia, ventricular fibrillation) — secondary to catecholamine release; greatest risk in cardiac surgery patients and those with underlying cardiac disease.
- Severe acute opioid withdrawal — in opioid-dependent patients; can cause extreme agitation, cardiovascular stress. Particularly dangerous in opioid-dependent pregnant women (fetal distress from acute withdrawal).
- Seizures — rare; reported in context of acute withdrawal in dependent patients.
Contraindications
- Known hypersensitivity to naloxone hydrochloride
- No absolute contraindications when used for life-threatening opioid overdose
- Relative caution: known opioid dependence (risk of precipitating acute withdrawal — use smallest effective dose)
- Relative caution: post-operative cardiac patients (risk of hypertension, arrhythmia from acute reversal — titrate carefully)
Available Indian Brands
| Brand | Manufacturer | Price (approx) |
|---|---|---|
| Nalone 0.4mg/mL injection | Troikaa Pharmaceuticals | ₹45/vial |
| Narcan 0.4mg/mL injection | Pfizer | ₹65/vial |
| Nalox 0.4mg/mL injection | Sun Pharma | ₹38/vial |
Monitoring Required
- Respiratory rate and pattern — primary endpoint of naloxone therapy (target >12 breaths/min)
- Oxygen saturation (SpO2) — continuous pulse oximetry until opioid effect resolved
- Level of consciousness and sedation score — re-sedation surveillance
- Heart rate and blood pressure — catecholamine surge during reversal
- Signs of opioid withdrawal in dependent patients (COWS score)
- Duration of monitoring: at minimum 2 hours after last naloxone dose; longer for long-acting opioids (methadone: 12–24h; fentanyl patch overdose: continuous infusion until patch removed and levels fall)
- In neonates: Apgar score, respiratory rate, color, tone, feeding after naloxone administration
- Symptom recurrence after naloxone discharge from ED — "do not let them walk out" until opioid effect duration accounted for
Patient Counseling Points
- Naloxone is a medicine that reverses opioid overdose. It can save a life in an emergency.
- For caregivers and family members of patients on opioids: Keep naloxone (Nalone injection or Narcan nasal spray where available) readily accessible at home. Know how to use it BEFORE an emergency occurs.
- To use the injection: draw 0.4mg (1mL) into the syringe; inject into the outer thigh (through clothing if needed in emergency) or upper arm. Call emergency services (112) immediately.
- Naloxone wears off within 30–90 minutes — the opioid may still be in the body. The person may go back to sleep (re-sedate) after naloxone wears off. Stay with them and repeat the dose or seek emergency care.
- IMPORTANT: After getting naloxone, the person must go to the emergency room — even if they appear awake and normal. The opioid may still be active.
- If using for opioid overdose reversal in a dependent person: they may wake up and immediately feel sick and agitated (withdrawal symptoms). Do not give more opioids — this is temporary and normal.
- Community naloxone access: In India, naloxone injection is available at selected government hospitals, AIIMS, NIMHANS, and drug treatment centers. Ask your addiction medicine team about take-home naloxone programs.
- Healthcare staff counseling: Always document the effective reversal dose — use this to calculate continuous infusion rate if long-acting opioid is suspected (2/3 of effective bolus dose per hour).
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Clinically reviewed by: Dr. Arun Bhaskar, MD, DM Palliative Medicine, Tata Memorial Hospital Mumbai
Last reviewed: 2026-04-01
References
- Boyer EW. Management of Opioid Analgesic Overdose. NEJM. 2012.
- Pfizer. Narcan (naloxone hydrochloride) Injection Prescribing Information. 2023.
- WHO. Community Management of Opioid Overdose. 2014.
- SAMHSA. Opioid Overdose Prevention Toolkit. 2023.
- CDSCO. Naloxone Prescribing Guidelines. India.