A health warning has been issued in Victoria after three people who took a drug they believed was cocaine overdosed on heroin and required emergency treatment.
The Department of Health said blood tests showed evidence of both heroin and cocaine, suggesting that heroin is likely being mixed into cocaine products being sold on the streets of Melbourne.
The process, known as “adulteration”, can produce life-threatening effects, especially for people who do not normally use opioids like heroin, the department said on Friday.
“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,” the department said.
Heroin is a very different substance from cocaine, although it often appears in a similar white powdered form. Cocaine produces 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.
“If you experience toxic drug effects, or are present when someone has an unexpected reaction, seek help immediately by calling Triple Zero (000).”
The drug alert warned Victorians to be aware of the signs of opioid overdose – which “include breathing slowly and reduced consciousness (meaning someone is hard to wake up). In some cases, the person may also have tiny pupils” – and carry naxolone, which reverses overdoses.
Naxolone is available free at some pharmacies, needle and syringe programs, Mental Health and Wellbeing Locals, the Victorian Pill Testing Service, and the controversial Medically Supervised Injecting Room in North Richmond.
In 2025 21 people died of drug overdoses in the City of Yarra, where the injecting room is located, the highest since it opened in 2018.
The warning comes after a similar alert was issued in Sydney last month when cocaine containing heroin caused two overdose deaths and left two other people fighting for life, following six similar non-fatal overdoses in March.
Header image credit: (Ed Dunens, CC BY 2.0, via Wikimedia Commons)
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