This information sheet explains what naloxone (Narcan) does, when it should be used, and how to give it.
What is naloxone?
Naloxone is a life-saving medication used to reverse an opioid overdose. Opioids are a type of medication that can be used for pain. The most commonly used opioids include morphine, hydromorphone, oxycodone and fentanyl.
Some people choose to use opioids that were not prescribed to them in order to get ‘high’. This is referred to as non-medical use. If a person takes too much of an opioid (i.e., taking more than the prescribed amount), this can cause their breathing to slow down or stop, which is a medical emergency.
Naloxone works by temporarily blocking the effects of opioids and allowing the person who has overdosed to start breathing normally again within a few minutes. Naloxone can be given as a spray into the nostril, or an injection into the muscle. Pharmacists can demonstrate how to administer naloxone, and videos are available online (nasal spray, injection).
You may hear naloxone called by its brand name, Narcan.
Having a naloxone kit is a safety step, like carrying an epinephrine injector or asthma inhaler. You may consider carrying naloxone:
- if you or someone you know uses opioids
- if you or someone you know spends time where substance use may be present (e.g., school, parties, community settings)
- if you or someone you know chooses to use non-medical opioids
- to have on hand to help in the event of an emergency.
Free, take-home naloxone kits are available without a prescription at many pharmacies in Ontario and across Canada. Click the links to find participating pharmacies in your province. Naloxone use is protected by the Good Samaritan Drug Overdose Act, which means you can’t get in trouble for administering it.
When should naloxone be given?
Naloxone should be given in the event of an intentional or unintentional overdose, whether from prescription opioids or non-medical opioids.
It is important to recognize the signs of an opioid overdose, which include:
- difficulty walking, talking or staying awake
- blue, purple or grey lips or nails
- very small pupils (also known as pinpoint)
- cold and clammy skin
- dizziness and confusion
- extreme drowsiness
- choking, gurgling or snoring sounds
- slow, weak or no breathing
- unresponsiveness (unable to wake up, even when shaken or shouted at)

Other signs, such as seizure-like movements, can also happen during an overdose, especially if multiple substances are taken together.
If you are in doubt, you should still respond to this emergency. Although naloxone is only effective for opioid-related overdoses, it is safe to administer naloxone to anyone, even if they are not intoxicated with opioids. If you are unsure whether someone is having an opioid overdose, it is better to give naloxone than not to.
See Know How to Recognize an Opioid Overdose, published by the Government of Canada, for more information.
How should naloxone be given?
Naloxone kits contain either naloxone nasal spray or naloxone injections and instructions for use. Pharmacists can provide instructions for how to use naloxone when you pick up the kit. There are also videos available online reviewing how to give naloxone: nasal spray, injection.
An opioid overdose is always an emergency. If you suspect someone is having an overdose:
- Call 9-1-1 as soon as you encounter an individual experiencing an overdose.
- Give naloxone (nasal spray, injection).
- If safe to do so, stimulate the person (try to wake them), and move them on their side in the recovery position. Provide first aid care if needed.
- After two to three minutes, if the person has not woken up or their breathing has not improved, give a second dose of naloxone.
- Stay on the phone with 9-1-1 and stay with the person until emergency help arrives. Leaving the person before paramedics arrive can result in death if the person stops breathing again.
How long does naloxone take to work?
Naloxone can begin to take effect within two minutes. If a response to the first dose is not seen within two to three minutes, a second dose can safely be given. The opioids may last longer in the body than the naloxone, which means the person experiencing the overdose may need extra doses of naloxone and care in a hospital. Always call 9-1-1 if you have to give naloxone to someone and stay with the person until help arrives.
What are possible side effects of naloxone?
Naloxone is overall safe to give, but some possible side effects include:
- swelling or dryness in the nose
- congested or runny nose
- shaking, sweating, nausea or vomiting after the person wakes up
- restlessness, increased blood pressure or heart rate.
What safety measures should you take when using naloxone?
It is important to call 9-1-1 and seek medical attention following an overdose. Even if someone responds to the naloxone dose, they should still seek medical attention to ensure they are medically stable and the overdose has been fully treated.
Naloxone kits should be kept at room temperature.
The expiry date should be regularly checked on your naloxone kits, as it is important to make sure the kit is up to date in the event it needs to be used. Naloxone kits that are expired or unused can be brought to a pharmacy for safe disposal.
What other important information should you know about naloxone?
The Good Samaritan Drug Overdose Act provides protections to people seeking and delivering emergency help during an overdose, even if you are under the influence of or in possession of illegal substances. Even if you are also using non-medical opioids, it is important to stay with the person until help arrives. It can save their life.
Resources
Know how to recognize an opioid overdose: https://www.canada.ca/en/health-canada/services/publications/healthy-living/opioid-overdose-poster.html
Where to find naloxone kits in Ontario: https://www.ontario.ca/page/where-get-free-naloxone-kit
Where to find naloxone kits in Canada: https://www.canada.ca/en/health-canada/services/opioids/naloxone.html#5
How to use naloxone nasal spray: https://pharmacists-2.wistia.com/medias/bk92ud4ee2
How to use naloxone injection: https://www.youtube.com/watch?v=8_YDm2ji4YU
References
Government of Ontario. Recognize and temporarily reverse an opioid overdose. Retrieved from https://www.ontario.ca/page/get-naloxone-kits-free.
Government of Canada. Naloxone. Retrieved from https://www.canada.ca/en/health-canada/services/opioids/naloxone.html.
Ontario Pharmacists Association. Naloxone. Retrieved from https://www.opatoday.com/naloxone/.
Canadian Pharmacists Association. Resource Round-up: Opioids & harm reduction. Retrieved from https://www.pharmacists.ca/news-events/news/resource-round-up-opioids-harm-reduction/.
Centre for Addiction and Mental Health (CAMH). CAMH virtual reality training for preventing opioid overdose deaths now available to the public. Retrieved from https://www.camh.ca/en/camh-news-and-stories/camh-virtual-reality-training-for-preventing-opioid-overdose.
Although naloxone is only effective for opioid-related overdoses, it is safe to administer naloxone to anyone, even if they are not intoxicated with opioids. If you are unsure whether someone is having an opioid overdose, it is better to give naloxone than not to.