A dangerous synthetic opioid recently detected in at least four states has been linked to one death and possibly two more as authorities warn of its toxic consequences.
Protonitazene has been found in South Australia, Queensland, Victoria and Western Australia with health officials confirming it is being mixed with other illicit drugs.
Two young men were treated for overdoses in SA last week and the death of an Adelaide man is now being investigated by the coroner with the drug suspected of playing a role.
A woman also remains in Royal Adelaide Hospital.
That follows two deaths in Queensland earlier this year where officials continue to investigate the circumstances, after a warning that protonitazene had been found in fake Xanax tablets.
The tablets appeared to be genuine and were being sold in Xanax-labelled bottles.
In Victoria, there was a series of hospital admissions in 2022 from overdoses linked to a yellow-coloured powder that users thought was ketamine but also included protonitazene.
In SA, there were concerns the opioid was being mixed with methamphetamine.
Drug and Alcohol Services acting state director Victoria Cook said drug users need to be aware they could be accidentally exposed to something more deadly than they believed.
"Even if used knowingly by a regular opioid user, (with protonitazene) there is a high chance of overdose and death," she said.
Protonitazene is a benzimidazole derivative with potent opioid effects that has been sold over the internet as a designer drug since 2019.
It was previously identified in a number of European countries, as well as Canada and the US.
In addition to the loss of consciousness and respiratory failure, symptoms can include shallow breathing, slow or erratic pulse, confusion, small pupils, unresponsiveness, and bluish or greyish skin from poor circulation.
The effects of protonitazene can be reversed by giving naloxone, also known as Narcan, and illicit drug users have been strongly encouraged to have a supply on hand.
Because of the potency of the drug, additional doses of naloxone may be required.
Royal Adelaide Hospital emergency physician and clinical toxicologist Sam Alfred said there were dangers associated with taking any recreational drugs.
"It is impossible to know where it has come from, what is in it and at what dose, and what effect it will have on the individual who takes it," he said.