Heroin is an opioid that can produce life-threatening toxic effects – especially if
you don’t usually use opioids.
Two people have recently required emergency care because they experienced heroin overdose after using what they thought was cocaine or methamphetamine. Specialised blood tests showed evidence of heroin as well as the intended drugs. This means heroin may be mixed into cocaine or methamphetamine (‘adulteration’) or mis-sold as these drugs (‘substitution’).
Opioids are central nervous system depressants that produce effects including pain relief, sedation and respiratory depression (slowed breathing). Small amounts of opioids can cause life-threatening overdose in people who have never or rarely used opioids.
Heroin is a very different substance from cocaine and methamphetamine, although it often appears in a similar white powdered form. Cocaine and methamphetamine produce stimulant effects, whereas heroin produces sedative effects and can lead to life-threatening overdose. Using heroin with depressants such as alcohol, GHB or benzodiazepines (such as Xanax or Valium) increases the risk of overdose.
Know the signs of opioid overdose and carry naloxone
Signs of opioid overdose include breathing slowly and reduced consciousness (meaning someone is hard to wake up). In some cases, the person may also have tiny pupils. 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 is safe to use even if you are not sure whether someone has taken opioids. Naloxone can be accessed free of charge at participating pharmacies, needle and syringe programs and the medically supervised injecting centre. You can find an approved naloxone provider on the Take Home Naloxone program webpage.
Reduce the risk of harm
If you experience toxic 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 take these precautions:
- Be aware that other false or contaminated drug products may circulate in Victoria, even if no specific warning has been issued about them.
- Get free naloxone and carry it with you – no matter what drugs you think you’re getting.
- Start low and go slow, and 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. Get the facts from the Alcohol and Drug Foundation .
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 28 March 2025