Naloxone for opioid overdose

Frequently asked questions about naloxone for opioid overdose

Naloxone is a medicine used to treat opioid overdose. If taken soon enough after an opioid overdose, it can save your life.

In Aotearoa New Zealand naloxone is available as an emergency kit or take-home kit which can come as an injection or a nose spray. These emergency kits are easy to use so that naloxone can administered by minimally trained laypeople (non medical) in an emergency.

On this page, you can find the following information:

What is naloxone?

Naloxone is a medicine used to treat opioid overdose. Opioids are strong pain medicines. Examples of opioids include codeine, morphine, oxycodone, methadone, fentanyl, tramadol and heroin. Opioids slow your breathing and affect your consciousness – if you take too much or overdose on opioids, your breathing may stop and you could die. Read more about opioids and who is at risk of opioid overdose.

Naloxone works by reversing the effects of opioids. It can restore normal breathing to a person whose breathing has shallowed or stopped as a result of an opioid overdose. Naloxone can be given by injection or nasal spray and works very quickly, within 2–5 minutes.

Opioid overdose is an emergency because it causes life-threatening problems such as slow or stopped breathing and unconsciousness.

When to use naloxone for an opioid overdose?

Naloxone is only used when a person shows signs of an opioid overdose. A person may have overdosed if they:

  • are very sleepy or hard to wake up (passed out)
  • have little or no breathing
  • are snoring deeply or making gurgling sounds
  • have blue lips or nails
  • have tiny pupils.

Note: Naloxone is only effective against opioid overdose. It doesn't work for overdose of other medicines, illicit drugs or alcohol. But, in an emergency, if you are unsure of the exact cause of the overdose and suspect it could be opioids, it is safe to use naloxone. See below can naloxone harm someone?

How do I use naloxone for an opioid overdose?

For detailed instructions on how to give naloxone see the leaflet in the emergency kit or the guides: Naloxone Injection Emergency Kit and Naloxone Nasal Emergency Kit.

Here are some important things to remember when using naloxone  
  • Check the person is in a safe place and that you can't wake them up.
  • Always call an ambulance (dial 111) and stay with the person until the paramedics arrive.
  • Turn them on their side to prevent choking (recovery position).
  • Take note of the time you administer the first and second naloxone dose so you can tell the paramedics.
  • A second dose is necessary if the person does not respond to the first dose. Naloxone takes a few minutes to work – allow at least 2-5 minutes between the first and second dose.
  • If after giving the second dose the person is not breathing, apply rescue breathing (2 breaths every 5 seconds). You need to get the person breathing. 
  • If the person comes around stay with them until the paramedics arrive – naloxone only lasts 20 minutes and they could drop again.

Do I still need to call the paramedics if naloxone has worked?

An overdose is always an emergency. Even if naloxone has been administered, always call for help.

Naloxone is active in the body for only 20–90 minutes, but the effects of most opioids can last longer. This means that the effects of naloxone are likely to wear off before the opioids are gone from the body, which could cause breathing to stop again. Naloxone may need to be used again, depending on the amount, type or method of consumption of the opioids (eg, oral, injection).

Where can I get an emergency naloxone kit from?

Naloxone is only available on prescription so you need to see your doctor so they can assess your needs. You may want to consider taking a friend or a family member with you to see your doctor so they can support you and learn how to use the kit. You can choose to have a naloxone injection or the nasal spray. 

The kit is not always free but some pharmacies can offer the kit at a low cost. If you are in Auckland, contact the Auckland Opioid Treatment Service (AOTS) for further information about participating pharmacies.

If you are taking opioids, have a plan. Talk about overdose with people you trust before it happens. Ask your healthcare provider whether you need an emergency naloxone kit. 

Once you have the kit, always keep the naloxone in a place where family, friends, and close contacts can easily access it in an emergency. Let them know:

  • that you have it, and where you keep it
  • to call 111 or get emergency medical help straight away in all cases of known or suspected overdose, even if naloxone is administered
  • how to recognise the signs and symptoms of an overdose
  • how to administer naloxone in the event of an overdose
  • to read the instructional leaflet or educational material that comes with naloxone before an opioid emergency happens, so everyone knows what to do.

Can naloxone harm someone?

No. It is safe to give naloxone any time you suspect an opioid overdose. It will not hurt if you are wrong about it being an overdose. People who receive naloxone for an overdose may wake up and go into withdrawal. Symptoms of withdrawal include:

  • feeling nervous, restless or irritable
  • body aches
  • dizziness or weakness
  • diarrhoea (runny poos), stomach pain or feeling a little sick
  • fever, chills or goose bumps
  • sneezing or runny nose
  • anxiety
  • fast heart beat
  • confusion.

Talk with your healthcare provider if you have questions about withdrawal symptoms.

Some people who take opioids can very rarely have more serious side effects following naloxone such as seizures, pulmonary oedema, and ventricular arrhythmias if a large dose of naloxone is administered.

Is naloxone just a "safety net" that allows users to use even more?

Research has found that having naloxone available does not encourage people to use opioids more. The goal is to prevent deaths from opioid overdose by distributing naloxone and educating people about how to prevent, recognise and intervene in overdose situations.


Learn more


Credits: Sandra Ponen, Pharmacist. Reviewed By: Maya Patel, MPharm PGDipClinPharm, Auckland Last reviewed: 03 Feb 2022