Metonitazene is a novel synthetic opioid
Opioids are central nervous system depressants. They typically produce a range of effects including sedation, short-term pain relief, and respiratory depression (where breathing slows or stops). Respiratory depression often appears more quickly with novel synthetic opioids (NSOs), increasing the risk of life-threatening overdose. NSOs are a leading contributor to overdose deaths world-wide.
Metonitazene is a potent NSO that is not often seen in Australia. Its potency is similar to fentanyl, estimated to be between 30 and 200 times that of morphine. This means it can produce life-threatening toxic effects in very small amounts. Metonitazene usually appears as a white, off-white or beige powder.
The Department of Health is aware of two serious recent hospitalisations associated with metonitazene. Patients experienced strong and fast-acting effects, leading to loss of consciousness, respiratory depression and hypoxia (insufficient oxygen for normal functioning).
Know the signs of opioid overdose – and carry naloxone
People who are expecting to use cocaine may not know how to recognise and respond to opioid overdose. Signs of opioid overdose to look out for include: breathing slowly, reduced consciousness (meaning someone is hard to rouse), or tiny pupils in some cases. More information about opioid overdose symptoms can be found on the Penington Institute .
Naloxone is an easy-to-use medication that can reverse opioid overdose – it’s safe to use even if you’re not sure whether someone has taken opioids. Naloxone is available for free from participating (a script is not required). The pharmacist will show you how to use naloxone. Alternatively, contact Harm Reduction for training from peers.
Using metonitazene or other opioids with depressants such as alcohol, GHB or benzodiazepines (‘Xanax’, ‘Valium’, ‘Mylan’, etc) increases the risk of overdose.
Reduce the risk of harm
If you experience adverse drug effects, or are present when someone has an unexpected reaction, seek help immediately by calling Triple Zero (000).
All alcohol and other drug use comes with risks, so:
- Be aware that other false or contaminated drug products may circulate in Victoria, even if no specific warning has been issued about them. Metonitazene may circulate in other forms.
- Make sure you’re in a safe environment with people you trust.
- Remember, even ‘pure’ drugs can produce serious side effects and death, and can interact dangerously with medications/pharmaceutical drugs.
Contact Harm Reduction Victoria’s DanceWize team for anonymous support and education from peers. Talk to DanceWize volunteers by email at info@dancewize.org.au.
If you or someone you know needs help with alcohol or drug use, call DirectLine on 1800 888 236 or visit for information and support to access treatment.
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Reviewed 04 August 2023