Kronic is marketed as "legal weed", and its creators say there have never been reports of negative side-effects in the seven years it has been on the market.

However, the Australian Medical Association said using Kronic could cause severe paranoia, anxiety and panic attacks, high heart rates, agitation and restlessness.

Associate Health Minister Peter Dunne said a report last year from the expert advisory committee in New Zealand had identified some negative effects, but had not been conclusive enough to make the product a controlled substance.

"My hope would be that if new expert advice becomes available then the expert advisory committee would reconsider it."

Mr Dunne said there were already restrictions in place under the Smoke Free Environment Act, which prohibits the sale to people aged under 18.

"That's probably not being given sufficient credence in the current discussions, there are already quite severe limitations on the availability of the product."

The passage of the Misuse of Drugs Amendment Bill was the next step in the process, Mr Dunne said.

"At this stage what I would expect would be that the Government make its views known later this year on the Law Commission's report, legislation would follow in a comprehensive way next year."

Meanwhile, three students at Auckland's Takapuna Grammar School have reportedly been suspended for smoking the drug on school grounds.

Police said many schools had taken action against Kronic-users under their smoking and drugs policies, and that they had received reports of students collapsing and vomiting from using the drug.