The father of a critically ill young Christchurch man says it was a "hell of a shock" to discover his son was skipping university to take a deadly party drug.
Michael, 20, is on life support with organ failure after taking 25B-NBOMe, a powerful synthetic hallucinogen linked to deaths in Australia and Asia.
He was one of six admitted to Christchurch Hospital last Wednesday after suffering adverse reactions to the drug, also known as N-Bomb or synthetic LSD, with his condition the most severe.
In an emotional statement released by the hospital, Michael's father Murray said his family was still trying to come to grips with the events leading up to this heart-breaking turn of events.
"It's been a hell of a shock. I didn't even know this stuff existed before last week," said Murray, who did not want the family's surname published.
"The other thing I'm quite shocked about is just how prolific the use of cannabis as well as all this synthetic stuff is."
Murray said he was unaware Michael had been dabbling in recreational drug use.
"I've had a couple of shocks over the past week. I thought Michael had been going to uni but he hasn't."
The father said it was difficult to offer advice to parents wanting to avoid this situation.
"Being a parent, it's all about trust," he said.
"I guess, it's probably watching the peer group. But sometimes it's the people you least expect."
The drug, sold as a white powder or in capsules, is known to cause hallucinations, confusion and agitation, and can sometimes trigger uncontrollable violent behaviour.
Recreational doses are measured in tiny microgram quantities, making it very easy to overdose.
Detective Senior Sergeant Jason Stewart said there was a similar cluster of Christchurch users requiring treatment about six months ago.
The investigation into the latest incident is ongoing, with police still keen to hear from anyone with information that may assist.
Police were working closely with Customs and other agencies nationwide to target users and distributors.
Anyone wanting help with drug addiction can contact the Drug and Alcohol Help Line: 0800 787 797, or email firstname.lastname@example.org.