Seven people are dead after using synthetic cannabis this month in Auckland, with ambulance staff saying they also see 20 users a day suffering "life-threatening effects" from the illegal drug.

The deaths have prompted the Chief Coroner and police to issue a public warning about synthetic cannabis.

Chief Coroner Judge Deborah Marshall said the seven dead are believed to have used synthetic cannabis recently or were found with it on them.

"I've also been advised by St John that there have been a significant number of non-fatal cases where people have been hospitalised after using the drug, which is known to cause potentially fatal seizures," Marshall said.

"While the police and coronial investigations are still at an early stage, and the final causes of death have yet to be established, the number of cases where synthetic cannabis appear to have been a contributing factor has prompted me to issue this public warning," she said.

Associate Health Minister Peter Dunne said he was "desperately concerned" that illegal, synthetic drugs were leading to deaths.

He also said that he warned of the consequences of having an unregulated market when synthetic drugs were banned in 2014 until they could pass a rigorous testing regime.

"The fact that you've got backyard manufacturers putting together goodness knows what in a totally unregulated market, supplying in a totally unregulated market to all sorts of people just creates the potential for this sort of tragedy to occur.

"This is precisely what we were trying to stamp out at the time of that legislation.

"I warned at the time ... that this would create a black market that would be far more dangerous than a regulated market. And sadly, that's what's it's proved to be.

"The testing regime is now in place, but it is not functional because the Government banned the use of animal testing to prove whether recreational drugs were low-risk. A non-animal test has not yet developed which can provide robust results about the risk level of a drug."

Dunne said he has urged officials to update him about any alternatives which would allow the testing regime to work.

The Government was also working with other countries on establishing an early warning system for psychoactive substances which might be coming across the border. It is likely to be in place next year.

"Had it been in place, that would have, I think, had some preventative effect in these instances.

"I guess they just tragically underline the risk of the situation we face once we have a totally uncontrolled environment, which we have at the moment."

Police are releasing CCTV footage that shows a man in the Auckland CBD last year unable to stand after smoking synthetic cannabis.

Detective Inspector Gary Lendrum said police are releasing the footage to highlight the effects of synthetic cannabis.

"We have grave concerns as users don't know what poisonous chemicals they are potentially putting into their bodies when they're smoking this drug," he said.

Lendrum said police have searched multiple properties arrested numerous people across Auckland as they crack down on the drug.

One synthetic cannabis operation in Avondale has resulted in 12 arrests over the past few months.

"It is a dangerous, illegal substance and we will arrest those who are selling this harmful drug and place them before the courts," he said.

St John medical director Tony Smith said the service was dealing with "up to seven deaths that appear to be linked to synthetic cannabis".

Smith said up to 20 people a day were showing up at hospitals, mainly in Auckland, with "life-threatening effects".

He said people were losing consciousness, having seizures and in some cases their hearts had stopped. St John "believed" the cases to be related to synthetic cannabis.

Smith said St John was "very concerned regarding the dangers of synthetic cannabis".

"We have seen a spike, particularly in Auckland, over the past month where we're seeing up to 20 [people] a day with some life-threatening effects following synthetic cannabis," Smith said.

"We're dealing with up to seven deaths that appear to be linked to synthetic cannabis. We don't know what this drug actually is; it's just been labelled synthetic cannabis."

Smith said St John didn't know if the product was a specific brand or type of synthetic cannabis, but that police were working to identify that.

Synthetic cannabis has referred to as a "zombie drug" after video emerged of users slumped and incoherent.

The New Zealand Parliament banned all legal highs in May 2014 until they could pass a testing regime, reversing interim approval it had given for low-risk products as part of the Psychoactive Substances Act.

 

What is synthetic cannabis?

Synthetic cannabinoids refer to a growing number of manmade mind-altering chemicals that are either sprayed on dried, shredded plant material so they can be smoked (herbal incense) or sold as liquids to be vaporised and inhaled in e-cigarettes and other devices (liquid incense).

These chemicals are called cannabinoids because they are related to chemicals found in marijuana plantS. Because of this similarity, synthetic cannabinoids are sometimes misleadingly called "synthetic marijuana" or "fake weed", and they are often marketed as "safe" legal alternatives to that drug.

In fact, they may affect the brain much more powerfully than marijuana. Their actual effects can be unpredictable and, in some cases, severe or even life-threatening.

Synthetic cannabinoids are included in a group of drugs called "new psychoactive substances" (NPS). They are unregulated, and are newly available on the market, intended to copy the effects of illegal drugs.

Synthetic cannabinoids act on the same brain cell receptors as delta-9-tetrahydrocannabinol (THC), the mind-altering ingredient in marijuana. So far, there have been few scientific studies of the effects of synthetic cannabinoids on the human brain, but researchers know that some of them bind more strongly than marijuana to the cell receptors affected by THC, and may produce much stronger effects. The resulting health effects can be unpredictable.

Source: US National Institute on Drug Abuse