Skip the ministry - leave it to GPs.

The Greens say doctors should be the ones able to prescribe cannabis-based medicines.

Associate Health Minister Peter Dunne has transferred the responsibility for signing off on drugs like Sativex and Tilray from his office, to the Ministry for Health.

Greens co-leader Metiria Turei said it's still a bureaucratic sign-off process. She said we need to go further - make sure the medicines are available, are cost effective for patients, and that it's doctors who decide who needs them.

"Doctors are in the best place to tell us what kind of medicines we have - not the minister, and certainly not the ministry of health."

Turei said our doctors are trusted with drugs that are far more addictive - like opiates.

"There is no real reason for the Ministry to now be signing off on these medicines - it is the doctors job. We go to our physicians because we trust them to take care of our health."