Drug overdoses will continue to kill young people in NSW if its government doesn't get on board with other states and begin pill-testing trials before summer, the Greens fear.
The warning follows the deaths of two people from heroin overdoses after using what they believed was cocaine at a recent house party at Glebe in Sydney's inner west.
Two others required hospitalisation.
Greens drug law reform spokesperson Cate Faehrmann said on Saturday Premier Chris Minns must follow the lead of other states and fast-track drug testing laws.
"As a result of a surge in drugs like ecstasy and cocaine being sold and consumed in Victoria that were unknowingly cut with lethal opioids, the Victorian Premier Jacinta Allan acted to save lives," she said.
"Two young Sydneysiders may be alive today if the premier acted upon the evidence like his Queensland and Victorian counterparts. I beg him to not delay any longer."
Victorian festival-goers will be able to test drugs for potentially deadly chemicals as soon as this summer as part of a pill-testing trial.
The trial will operate at 10 festivals and other events over 18 months and was announced by Ms Allan in June.
A fixed site will open in mid-2025 somewhere close to nightlife and transport in inner Melbourne.
Ms Faehrmann said more lives will be lost if changes are not made before the NSW government's drug summit, which will reach Sydney on December 4 and 5.
"The premier can't in all conscience sit back for another three months waiting until the government concludes its drug summit before introducing drug checking in NSW, " she said.
"Increasingly dangerous drugs are in circulation now ... tens of thousands of people in this state will use illegal drugs in the months ahead, particularly as we come into the summer party season."
The summit will bring together medical experts, police and drug users to build consensus on the way NSW deals with drug use and harms.
NSW Health chief addiction medicine specialist Hester Wilson warned users after the recent Sydney deaths that consuming a single line of heroin could cause an overdose.
"It is important people recognise the signs of an opioid overdose early and know how to respond," she said.
A similar warning was issued in the ACT on August 30, after four people died of suspected drug overdoses in a two-month period.
Police suspected either high drug purity levels or the presence of synthetic opioids including fentanyl were behind the deaths.
Dr Wilson said people who planned to use drugs such as cocaine, MDMA and opioids should carry naloxone with them.
Naloxone, which does not require a prescription, reverses the effects of opioids.
Queensland also recently announced pill testing would be allowed for the first time, while the ACT is currently trialling a fixed-site checking service.
According to the Australian Drug and Alcohol Foundation, pill testing, or drug checking, isn't a new idea and has been conducted in Europe since the 1990s.
It's currently available in 20 countries across Europe and the Americas, as well as New Zealand.
