Cocaine users die of heroin overdoses after consuming tainted drugs at Sydney house party

Two people recently died of heroin overdoses after using what they thought was cocaine at a house party at Glebe in Sydney’s inner west, while another two people were hospitalised, New South Wales authorities say.

Police are investigating the deaths of a 31-year-old man at Glebe in the early hours of Friday 30 August and a 43-year-old woman at Newtown about 8.45am the same day, NSW police said.

The state health department on Friday warned people who use illicit drugs to carry naloxone – the life-saving medication used to treat opioid overdoses. Experts said opioids were increasingly being mixed with other stimulants in Australia.

“Heroin and other opioids can be sold as or found in cocaine, methamphetamine and MDMA,” the state’s chief addiction medicine specialist, Dr Hester Wilson, said.

“You cannot always tell the difference between these drugs by appearance. In light of this detection, people who use drugs such as cocaine, methamphetamine, MDMA or opioids should carry naloxone.

“A heroin overdose could quickly result from a single line.”

Related: Researchers urge more Australian pharmacies to stock anti-opioid overdose drug naloxone

The federal government this month rolled out a new online map listing 4,600 pharmacies that provide naloxone free under the national “take home naloxone” program. The drug is available anonymously and without a prescription.

Naloxone is highly effective at blocking opioids such as heroin and oxycodone from attaching to receptors in the brain. The effect is temporary and after administrating naloxone it is vital to call triple zero for an ambulance, NSW Health said.

The commonwealth’s map pinpoints the nearest provider of naloxone using a postcode or location – with no information retained to assure privacy.

The federal health minister, Mark Butler, said the naloxone program “only works if people know where and how to access the free medication”.

“Having a searchable map online makes it much easier for people at risk of overdose, their family, friends and carers to have a ready supply in a form that suits their circumstances,” Butler said.

The NSW overdose deaths come after four people were found dead in Melbourne with opioids detected in their bodies in July. The Victorian health department had previously issued a drug alert for cocaine laced with protonitazene – a novel synthetic opioid that is up to 100 times more potent than heroin.

Wilson said on Friday: “It is important that people recognise the signs of an opioid overdose early and know how to respond. Opioids such as heroin can cause pin-point pupils, drowsiness, loss of consciousness, slowed breathing/snoring and skin turning blue/grey and can be life-threatening.”

Related: Synthetic opioid detected in bodies of four people found dead in Melbourne home

Dr Mary Ellen Harrod, the chief executive of NSW Users and Aids Association, said “these are tragic and preventable deaths”.

She said people needed to be aware of the risks and be prepared to take simple steps to prevent harm, including never taking drugs alone as well as carrying naloxone.

Prof Suzanne Nielsen, the deputy director of the Monash Addiction Research Centre, said with Australia’s unregulated drug market it was impossible to know what was in them without testing.

“If people are consuming cocaine or another stimulant, and not intending to use opioids, if they aren’t used to taking opioids and don’t have any tolerance to the effect of opioids, that can be very dangerous,” Nielsen said.

Opioids could slow your respiration, reducing the drive to breathe, which is what caused overdoses, she said.

When someone took opioids regularly with a known dose, they did have some tolerance to the effects, which was somewhat protective, she said.

“But someone who’s not used to taking that same dose – that can be fatal.”