Approval for cannabis-based products for medicinal use will no longer require ministerial sign-off, under changes announced by the government.

Associate Health Minister Peter Dunne has delegated decision-making for the prescribing of all cannabis-based products to the Ministry of Health.

"When applications first began to be received it was my view that the final decision appropriately lay at ministerial level, rather than exposing officials to risk, given the complicated and contentious nature of the issue - that is to say the buck stopped with me", said Mr Dunne in a statement.

"I have approved every application that has come before me with a positive recommendation - within a matter of minutes once the application came across my desk."

Since the first application was approved, guidelines have been developed, consulted on and simplified, Mr Dunne said.

That had allowed specialists who were interested in accessing such products for their patients a "clear, straightforward and unobstructed pathway" to acquiring the appropriate products, he said.

"I am satisfied that with the development of these guidelines, and with a number of successful applications having been subsequently completed, any risk associated with the early processes has largely abated and I have confidence in the Ministry of Health to handle the process in its entirety from now on."

Approval for pharmaceutical-grade cannabis products was delegated in a similar way some years ago.

Alex Renton was given medicinal cannabis before his death. Photo: Facebook

The guidelines were initially introduced in 2015 in response to the case of Alex Renton who suffered an acute, prolonged epileptic seizure. Part of his treatment before his death at the age of 19 was medicinal cannabis.

The Nelson teenager was the first person in New Zealand to be granted an exemption to use the drugs after Mr Dunne approved it as a one-off treatment. His mother, Rose Renton presented a petition to Parliament urging the government to make medicinal cannabis more readily available.

Helen Kelly campaigned to get medicinal cannabis legalised Photo: RNZ / Alexander Robertson

Trade unionist Helen Kelly fought last year to get medicinal cannabis legalised as her terminal lung cancer advanced.

She had sought approval from the Health Ministry to use imported cannabis oil from the US, but gave up on the application after it proved too difficult for her oncologist to provide the information the ministry wanted.

Her championing of the issue brought it to the forefront of public consciousness, with polls conducted in the wake of her cancer diagnosis finding up to 79 percent of people supported the use of cannabis for medical reasons.

Mr Dunne said today he would write to the New Zealand Medical Association and the Pharmacy Society of New Zealand outlining his "ongoing expectation that medical professionals consider the prescribing of cannabis-based products with an open mind".

To provide "additional clarity" he would include a list of internationally available cannabis-based products that are either pharmaceutical grade or good manufacturing practice certified.

The Medical Association said a list of internationally available cannabis-based products would streamline the process for doctors to sign off paperwork to send to the ministry.

Chair Stephen Child said the cannabis-based products would simply join a long list of restricted medicines that can be given out only when certain conditions are met.

Medical Cannabis Awareness co-ordinator Shane Le Brun said moving approval to the ministry would not be significant, but compiling a list of approved products would make a difference.

Mr Le Brun said it was a matter of the ministry becoming confident in the products people were applying for.

Last December Mr Dunne removed the requirement for Ministry of Health approval to prescribe Sativex for multiple sclerosis.