Naloxone — NZ Medication Guide

📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.

What is Naloxone?

Naloxone is an opioid receptor antagonist used to reverse opioid overdose — a life-saving emergency medicine. This medication is funded by Pharmac and available through harm reduction programmes; take-home naloxone available without prescription.

What is Naloxone Used For?

Used to reverse life-threatening opioid overdose (heroin, prescription opioids, fentanyl) — restoring normal breathing. Used in hospitals for opioid-induced respiratory depression, and in community take-home programmes.

How Does Naloxone Work?

Competitively displaces opioids from all opioid receptor types (mu, kappa, delta), reversing CNS and respiratory depression within 2–5 minutes. Duration 30–90 minutes — shorter than many opioids, so repeat doses may be needed.

How to Take Naloxone

For overdose: 0.4–2 mg IV, IM, or intranasal (Narcan® 4 mg nasal spray). Repeat every 2–3 minutes until breathing normalises. Always call 111 even after administering — the opioid may outlast naloxone’s effect.

Common Side Effects of Naloxone

• Opioid withdrawal symptoms from reversal (agitation, sweating, nausea, pain)
• Tachycardia
• Hypertension

Serious Side Effects — Seek Medical Attention

Contact your doctor or call 111 immediately if you experience any of the following:

• Re-narcotisation (return of opioid effect when naloxone wears off — requires repeat dosing and monitoring)
• Pulmonary oedema (rare — after rapid reversal in ICU settings)

Drug Interactions

Naloxone may interact with other medicines. Always inform your doctor and pharmacist of all medications you are taking. Key interactions include:

• Opioid medicines (pharmacological antagonism — intended interaction)

New Zealand Prescribing Information

Narcan® (naloxone 4 mg/0.1 mL nasal spray) is available without a prescription at NZ pharmacies and through needle exchange services and harm reduction programmes. Anyone at risk of opioid overdose or with a family member at risk can obtain it. NZ Good Samaritan legislation protects people who call 111 or seek help for someone overdosing.

Frequently Asked Questions

Can anyone carry naloxone in New Zealand?

Yes — naloxone nasal spray (Narcan®) is available without prescription in NZ. Training in recognising and responding to overdose is available through needle exchanges and community health services.

How do I know if naloxone is working?

Within 2–5 minutes, the person should begin breathing normally, regain consciousness, and colour should return to their lips. If no response after 2–3 minutes, give another dose and call 111 immediately.

References & Further Information

The following New Zealand and international resources were used to inform this page:

• New Zealand Formulary — Naloxone
• NZ Drug Foundation — Take-Home Naloxone
• Pharmac — Funded Medicines Schedule

⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for current information.

Reviewed by a Registered Pharmacist NZ