Last updated : March 26, 2017
Naloxone hydrochloride (trade name Narcan®) is a drug that can reverse opioid overdose. It can also be used to treat respiratory depression during pain management or after an anaesthetic.1
It works by blocking opioid drugs, such as heroin and methadone, from attaching to opioid receptors in the brain.1
Naloxone can be injected intravenously (into a vein) or intramuscularly (into a muscle) by medical professionals, such as paramedics. It can also be administered by family and friends of people who use opiates. Speak with your doctor or general practitioner for more information.
It can also be taken as a nasal spray; however, naloxone nasal spray is not registered for use in Australia at this time.
Naloxone can be administered by authorised medical personnel such as ambulance officers. As of 2016, naloxone can be purchased over the counter at pharmacies and chemists or via prescription from your GP as an ampoule to be injected into the arm or leg. Read more about overdose prevention and the administration of naloxone.
Naloxone cannot be used to get high, so it has no potential for misuse.
There is no evidence that extended use of naloxone can cause harmful physical effects or dependence. People who take naloxone do not develop a tolerance to its effects and there have been no reported deaths from naloxone overdose.1
The following side effects may be experienced:
People who have been revived with naloxone after overdosing on opioids may experience a strong urge to take more opioid drugs, especially if they are addicted.
Taking opioid drugs after naloxone is very dangerous. Naloxone only stays in the body for a short period of time (1 to 1.5 hours) whereas heroin and other opioid drugs stay in the body for much longer. The effects of sustained-release opioids like OxyContin® and MS Contin® can last for over 12 hours, so naloxone will wear off long before the opioid has left the system. This means that taking more opioids after taking naloxone could cause a second overdose.3