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 overdose, it can save your life.

On this page, you can find the following information:

What is naloxone?

Naloxone is used to treat opioid overdose. An overdose is an emergency.

  • Opioids are strong pain medicines. Examples of opioids include morphine, oxycodone, methadone, fentanyl and tramadol.
  • Taking too much of an opioid can cause respiratory depression and death. 

Naloxone is a medicine used to treat an opioid overdose. It's available on prescription. If you access an opioid treatment service or needle exchange, you may be offered an emergency naloxone kit.

Naloxone is not effective for overdoses on other drugs or medicines, only on opioid overdoses. However, if you think you or someone else may have overdosed but you're not sure on what, it's okay to use naloxone anyway. It won't cause harm.

When is naloxone used?

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.  

Image credit: Opioid overdose family support toolkit Ohio State University, US

If you can’t get a response from someone, don’t assume they are asleep and don't leave them alone. Unusual or deep snoring is a common sign of overdose. Do not leave people to ‘sleep it off’. Make sure your family and friends know about these signs of an overdose. 

If you think you or someone else may have overdosed but you're not sure, it's okay to use the kit anyway. If you have a kit, always have it with you because you never know when you might need it.

Who is at risk of an opioid overdose?

You are at greater risk of an opioid overdose if:

  • you mix opioids with alcohol or other medicines such as benzodiazepines (sleeping tablets)
  • you haven’t used opioids in a while (after detox, after a period of abstinence/not using or after time in prison or police cells)
  • you are using alone
  • the drug is stronger than expected. 

What to do in an opioid overdose

1. Check the person is in a safe place and that you can’t wake them up.
2. Call an ambulance (111).
3. Make sure their airways are clear and place the person in the recovery position.
4. Give them a naloxone injection into the muscle of their upper arm or thigh. 
5. After injecting into the muscle, take note of the time you do this so you can tell the paramedics.

Naloxone begins to work in 2–5 minutes.

6. If the person doesn't wake up in 3 minutes, give a second dose and record the time you do this.
7. If the person is not breathing, apply rescue breathing (2 breaths every 5 seconds) because naloxone is not effective against respiratory depression. You need to get the person breathing! This will make sure they get enough oxygen to their brain.
8. If the person comes, around stay with them – naloxone only lasts 20 minutes and they could drop off again.

Always go to the emergency room after using naloxone. Doctors can make sure the overdose has been reversed.

For more detailed instructions, see Naloxone emergency kit

What's in a naloxone kit?

Rescue kits come with instructions. The kit may contain:

  • naloxone glass ampoules or nasal spray
  • clean syringes and needles in sealed packs
  • alcohol swabs. 

There is also a naloxone nasal spray (Nyxoid) available that contains 2 single use spray units. Each single use spray can be used instead of an ampoule in step 4 and 6 above.

Can naloxone harm someone?

No. It is safe to give naloxone any time you suspect an 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.

Talk with your doctor if you have questions about withdrawal symptoms.

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 of distributing naloxone and educating people about how to prevent, recognise and intervene in overdoses is to prevent deaths. 


  1. Naloxone hydrochloride NZ Formulary
  2. Having naloxone on hand can save a life during an opioid overdose Food and Drug Administration, US
Credits: Sandra Ponen, Pharmacist. Reviewed By: Nikki Anderson, Senior Addictions Pharmacist, CADS, Waitemata DHB and Angela Lambie, Pharmacist, Auckland Last reviewed: 19 Oct 2020