There's been a huge spike in the number of people dying from synthetic cannabis.
Provisional figures from the coroner show between 40 - 45 people died in the year since last June - in the previous five years there was only one death.
The figures are causing doctors, families and the Drug Foundation to call for swift action to get it off the streets.
Synthetic cannabis was outlawed in 2014, and before that, it could be bought over the counter at the local dairy.
One ex-user, who wanted to remain anonymous, described what the drug did to her.
"You kind of just spin out, like you can't really move, you kind of just turn into a zombie," she said.
"You kind of just close your eyes and you're not really you anymore ... it makes you vomit sometimes."
She and her partner kept using it after it was made illegal, until one day things got too much.
"We couldn't find any. We'd run out and we had none left ... and I just lost it," she said.
"I was rolling around on the ground, like truly just screaming, ripping my clothes off myself and that was when my partner decided 'that's enough, we're not doing it anymore'."
St John Ambulance said it received about 30 callouts a week from people in trouble after taking the drug.
A doctor in the Wellington hospital's emergency department, Paul Quigley, said deaths were increasing because batches were becoming too potent for the body to handle.
The batches were manufactured from chemicals discarded by pharmaceutical companies, he said.
"The pharmaceutical companies are spending billions of dollars in trying to work out what parts of the cannabis plant could be used as a pharmaceutical drug to relieve pain, stop seizures, help people with a condition known as spasticity."
Those drugs were then thrown out by the companies, and picked up by the black market.
Dr Quigley said the first instance of this was back in 2006, but he said there had been a recent resurgence.
"It's very easy to get these agents from overseas in a liquid form. The cannabis market itself appears to be reasonably difficult and expensive at the moment and so the drug dealers are dealing in this much cheaper, easier to make and provide product."
He said manufacturers and dealers did not realise how strong these chemicals were and that they could cause users to suffer serious side effects including vomiting, seizures, hallucinations and arrhythmia.
Some users also reported suffering suicidal thoughts.
Harley Pataka killed himself in 2014 at the age of 23.
His mother, Katie Bayliss, said her son was a happy and well-loved boy, who enjoyed skating with his friends.
But that all changed when he became addicted to synthetic cannabis, she said.
"He became withdrawn, angry, a friend of mine told me that the weekend before he passed away she went over to where he was living and she walked in and she slapped his leg and he just looked at her as if he didn't even know who she was."
Where to next?
Ms Bayliss said her family had been ripped apart by the drug, which she said could be eradicated by the decriminalisation of marijuana.
The executive director of the Drug Foundation, Ross Bell, agreed.
"If we did have a regulated market for natural cannabis then we could have gone a long way to avoid, you know, many of these problems," he said.
"And even at the time when the country was having the big debate about legal highs there were lots of arguments saying that actually, you know, lets legalise natural cannabis to get rid of synthetic stuff."
Need to Talk? Free call or text 1737 any time to speak to a trained counsellor, for any reason.
Lifeline: 0800 543 354 or text HELP to 4357
Suicide Crisis Helpline: 0508 828 865 / 0508 TAUTOKO (24/7). This is a service for people who may be thinking about suicide, or those who are concerned about family or friends.
Depression Helpline: 0800 111 757 (24/7)
Samaritans: 0800 726 666 (24/7)
Youthline: 0800 376 633 (24/7) or free text 234 (8am-12am), or email firstname.lastname@example.org
What's Up: online chat (7pm-10pm) or 0800 WHATSUP / 0800 9428 787 children's helpline (1pm-10pm weekdays, 3pm-10pm weekends)
Kidsline (ages 5-18): 0800 543 754 (24/7)
Rural Support Trust Helpline: 0800 787 254
Rainbow Youth: (09) 376 4155
If it is an emergency and you feel like you or someone else is at risk, call 111.