A 21-year-old man's decision to take the potent psychedelic drug NBOMe nearly cost him his life.

A former university student who spent more than a week in a coma after taking the potent psychedelic drug NBOMe had to learn to eat and walk again.

The 21-year-old man, who would only give his name as Michael, has spoken publicly for the first time about the experience that nearly ended his life last year to warn others about the dangers of taking psychoactive substances.

Michael's father spent many hours in Christchurch Hospital wondering whether his son would ever wake up and did not believe the penalty for supplying drugs like NBOMe, also known as "N-Bomb", was tough enough.

SUPPLIED A 21-year-old man lies in a coma at Christchurch Hospital after taking the potent psychedelic drug NBOMe last year.

Michael was with a friend in a forest near the Ashley River, north of Christchurch, last year, when he took the synthetic drug, which mimics lysergic acid diethylamide (LSD).

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Within seconds he was convulsing and had become incoherent.

NBOMe is a powerful psychedelic drug that has been linked to deaths overseas.

"The last thing I remember was having a full out-of-body experience like I left my body and . . . I felt like there was some other force putting me on the scales deciding whether I should live or die," he said this week.

Michael was flown to Christchurch Hospital where he spent at least 10 days in a coma. During that time his kidneys shut down and his life hung in the balance. His friends and family wept at his bedside.

"It kind of shattered my world," Michael's father said.

"The biggest thing was walking into the room when he finally did recover consciousness and seeing . . . his eyes light up and . . . [hearing] the words 'I love you Dad'. I'll never forget that."

Michael said he had to learn to eat and walk again after he was discharged from hospital.

Physically and mentally he had recovered from the ordeal but his immune system was still weak and he often got sick.

Michael said he had not taken recreational drugs since and likely never would ever again.

"I still see a lot of people . . . taking these drugs even though they've seen what I've been through. It's very frustrating knowing it's so easy . . . for the same thing to happen [to someone else]. They say they know what they're putting in their body, but really they don't," he said.

"[Psychoactive substances] are not something that should be messed with."

Michael said he could not remember how he sourced the NBOMe, because the experience had erased that part of his memory. However, he thought he was buying another hallucinogenic psychoactive substance called DMT.

"The people are just selling them [drugs] to get a quick buck and not realising the effects they can have," he said.

Police arrested Jacob Douglas Wanhalla, from Kainga, in connection with the drugs Michael took last year.

Wanhalla later admitted selling a psychoactive substance and was sentenced to community work and supervision.

Michael's father said the penalty for supplying unapproved psychoactive substances (a maximum of two years imprisonment) needed to be harsher to deter dealers.

"I would encourage people to talk to their kids about them [the drugs] and if at all possible explain the effects and the possible outcome. It's terrible stuff. Try and keep your kids safe."

New Zealand Drug Foundation chief executive Ross Bell said the country's black market was "swamped" by unknown and "probably very dangerous" substances that were being sold as drugs like cannabis, LSD and ecstasy.

Harsher penalties had not stopped New Zealand's drug problem previously, Bell said. He believed users needed to be supplied with better information about new drugs on the black market.

Officials have previously said NBOMe should be treated like LSD – a class A controlled drug along with heroin, cocaine and methamphetamine (P)

Work was under way to have it reclassified under the Misuse of Drugs Act, they said.

Last week, police in Christchurch seized many kilograms of synthetic cannabis worth potentially millions of dollars.

Detective Senior Sergeant Jason Stewart said the investigation, which had interrupted a major South Island supply chain, was ongoing.

WHAT IS NBOME?

NBOMe is a potent series of synthetic hallucinogenic drugs that have been linked to deaths overseas.

The most common substances in the group are 25I-NBOMe, 25B-NBOMe and 25C-NBOMe.

They are often sold in blotter tabs by drug dealers as LSD because its effects are very similar. They can also be sold in capsules, tablets or bags of powder.

NBOMe emerged in New Zealand in 2012.