Vapes, depressants and ecstasy are being laced or replaced with extremely potent synthetic drugs, say experts who fear an imminent overdose crisis.
Nitazenes, a group of synthetic opioids, have already caused dozens of overdose deaths in Australia in 2024, harm-reduction advocates said on Tuesday.
Few users realise they have consumed the substances, despite them being found in numerous powders and tablets bought on the street or online, including cocaine, MDMA and heroin.
The synthetic opioids have also been found in vape liquids and counterfeit medicines such as benzodiazepines and oxycodone.
The drugs also evade fentanyl test strips.
"Nitazenes are like nothing else we've seen in Australia," Unharm chief executive Will Tregoning said.
"These can be 500 times stronger than heroin and just two milligrams, an almost invisible speck, can be enough to cause fatalities."
The concern prompted calls for a wider rollout of an easily administered overdose reversal medication, and for NSW follow Queensland and the ACT in adopting drug checking.
Two Victorian coroners in March urged a drug-checking trial after finding a heroin user died unaware he was taking the dangerous synthetic opioid drug.
Health authorities in NSW and South Australia have issued multiple urgent warnings about nitazenes being sold as black-market oxycodone or other substances.
A plan backed by MPs, union heavyweight Gerard Hayes, harm-minimisation advocates and the Royal Australian College of General Practitioners also calls for a public campaign to increase community awareness and response capacity.
The reversal medicine naloxone could be bought from pharmacies but awareness was low, Dancewize NSW's Caitlin Dooley said.
"People are prepared for one risk but not the risk they are facing," she told AAP.
"They don't have the tools, skills or knowledge to help themselves, and it's terrifying because these are young people.
"Young people shouldn't die from one bad decision."
The plan was reasonable, would avoid foreseeable deaths and needed to be fast-tracked, Legalise Cannabis MP Jeremy Buckingham said.
It comes ahead of the NSW Labor government's long-promised drug summit, heading to regional areas in October and Sydney in December.
The last summit, held in 1999, led to the introduction of a nation-leading medically supervised injecting room in inner-city Kings Cross that has been credited with saving numerous lives.
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