The vast majority of viewers tuning into The AM Show on Monday support medicinal cannabis.

A (non-scientific) poll on the Newshub website found 94 percent of respondents backing its legalisation.

It comes after oncologists claimed at the weekend half their patients are using cannabis to ease their suffering.But don't expect the Government to ease up the rules anytime soon.

Speaking to The AM Show on Monday, Prime Minister Bill English said there's already a "compassionate" and legal route for patients to get cannabis products - if they need them.

"The minister's just changed the rules so that's a little bit easier, with the Ministry of Health now approving it instead of each one going to the minister.

"As far as we can see, that's going to work pretty well and we don't want to take it any further."As reported on The Nation at the weekend, between 40 and 60 percent of oncologist Anthony Falkov's patients have reported using the drug.

"Most patients use it firstly because they hope it'll work and improve their cancer control rates... Secondly, they're using it for pain, and thirdly they're using it basically for appetite stimulation, and a lot of them are using it for anxiety and nausea and vomiting."

But Mr English says the science backing cannabis' effect on cancer is "reasonably limited", and until that changes, the law won't.

"We don't want an official marijuana industry. We're not going to be legalising it."

He fears increasing access to medical products based on cannabis will increase recreational use.

"We just think the long-term damage of large-scale use of marijuana is pretty bad."

University of Victoria research on the effects of legalising cannabis use in the US found a 10 to 15 percent increase in use amongst adults, but no difference for teenagers. Use of harder drugs like cocaine and heroin appeared to drop, based on police and hospital data.

Good arguments both ways

Chair of the New Zealand Medical Association Stephen Child told The AM Show there's been plenty of research already.

"There's been 10,700 articles so far reviewing this subject, and there is evidence to suggest that it is beneficial in some cases… but there's also evidence of risk."

Dr Child says there's frustration in the medical community that medicinal marijuana is being used as a "backdoor entry" for recreational use.

"There's some good arguments to suggest that's something we should be considering, but that's not a medical discussion and it's not a medical argument."

The cost

Sativex, the most commonly prescribed cannabis-based drug in New Zealand, hasn't been as effective as some doctors hoped.

"We thought Sativex was going to be somewhat of a miracle drug, but it hasn't actually been as good as we thought it was going to be," Rick Acland, former medical director at Burwood Hospital, told The Nation.

It also costs between $1000 and $1500 a month, beyond the reach of most people.

Associate Health Minister Peter Dunne says he would welcome trials of other products here in New Zealand, but our market is too small.

"We need manufacturers with product to say 'we would like to trial these formulations in New Zealand', and the sad truth is that for many of those manufacturers they do not see New Zealand as a sufficiently large market to make it worthwhile," he told The Nation.

"It's the same story we have for clinical trials generally, but there's no prohibition for sourcing cannabis for medical trials in New Zealand."