The pills are labelled as legitimate painkillers like Xanax, a drug popular in the US but not available in Australia.
Queensland Health’s John Allan warned some users may not realise they are taking counterfeit drugs.
“Nitazenes, including protonitazene, are a group of synthetic opioids that can be as strong or stronger than fentanyl,” he said.
“They have been detected in Queensland and other states and territories in various forms including tablets, powders and liquids.”
Protonitazene can result in respiratory failure, loss of consciousness, coma and death.
Read Related Also: David Haye wishes girlfriends Una Healy and Sian Osborne a happy Valentine’s as he ‘confirms’ throuple
Other symptoms of opioid overdose include shallow breathing, slow or erratic pulse, confusion, small pupils, unresponsiveness, and bluish or greyish skin from poor circulation
“This highlights why people should not source substances illegally,” Allan said.
“You could unknowingly be taking a potentially fatal substance.”
Anyone who experiences a suspected overdose should seek medical attention immediately.