Trade unionist Helen Kelly says she's frustrated the Ministry of Health has turned down her application to use medical cannabis.

Photo: RNZ / Alexander Robertson

Ms Kelly stood down from her role as Council of Trade Unions president last year after she was diagnosed with terminal lung cancer.

She applied to the ministry last month to use a cannabis oil product, which was available in some parts of the United States, to help control her pain and nausea.

The ministry responded this morning, saying it was deferring the application because it did not contain enough information, she said.

"Basically they've said my doctor hasn't described enough how the current drugs I'm taking are not working," she said.

"He's described all the drugs I'm taking and he's a senior oncologist and he said, 'I'm seeking permission to give her cannabis', but ... they're second-guessing him."

She would try to work out what more information the ministry wanted and re-apply, she said.

The ministry had suggested she apply for another cannabis product, Sativex, but its chemical make-up meant people who took it experienced greater hallucinatory effects than the product she wanted to use, Ms Kelly said.

"It makes you stoned."

She would continue taking cannabis that she had acquired in New Zealand, but it was not an ideal situation, she said.

"People are putting themselves at risk providing me with this stuff and I don't like that."

The Ministry of Health should be putting together a list of medical cannabis products it would be willing to approve so that people who were often very sick did not have to spend so much time researching the options themselves, Ms Kelly said.