An emergency response team has been set up to identify what is in the synthetic cannabis that has caused eight deaths in the past month.
Police said this week they were aware of reports that there was a "bad batch" of synthetic cannabis but there was no scientific evidence to back that up.
Associate Health Minister Peter Dunne says what is happening in New Zealand seems to mirror what has been happening in other countries.
"I have set up an emergency response team in Auckland involving the Ministry of Health, Auckland's district health boards and the police to work together to identify the particular substances being used, have them tested, and provide appropriate treatment for affected persons," he said on Thursday.
"In the longer term though, we need better information about the flow of new psychoactive substances potentially coming over our borders."
Mr Dunne said there were potentially hundreds more such substances yet to be released.
"That is why New Zealand is working with other countries to establish an early warning system by which we can share information with others on current developments."
He expects it to be in place next year.