Updated: 2:48pm The parents of a 7-year-old girl have the green light to use medicinal cannabis to control :their daughter's severe seizures.

Karen and Adam Jeffries have Health Ministry approval to give their daughter Zoe the cannabis oil-based mouth spray Sativex for the next six months.

"It has been a long time coming, it's great news," mum Karen Jeffries told the Herald on Sunday.

"We have been on it for a couple of weeks so it is early days but she is a lot more settled already."

The Rotorua girl is understood to be one of the youngest in New Zealand to receive the medicine.

Another child, a 5-year-old, has been approved use.

The Jeffries began researching medical cannabis in 2013 in the hope of finding a drug to reduce the hundreds of seizures their daughter suffers each day.

Zoe has uncontrolled epilepsy, spastic quadriplegia cerebral palsy, microcephaly, cerebral visual impairment and is tube fed. She has had severe seizures since birth.

"You want to try to control the seizures that cause additional brain damage, but also you want to allow your child a life, to be awake and not drowsy, or have the strength to stand or just hold their head up high," her father Adam said.

The medicine hadn't dramatically changed the number of seizures Zoe suffers but this week, teachers at Glenholme School in Rotorua said she returned to school happier.

"When she started school this week they saw a completely different child," Karen Jeffries said. "She was a lot more settled and was able to cope with noise and was a lot less distressed."

Sativex is the only approved cannabis-based medicine registered with Pharmac but is not funded. It can be prescribed by a doctor but each case needs Health Ministry approval. To date, there have been 97 ministerial approvals, and there are currently 27 users of Sativex.

Each bottle lasts around four weeks and costs $1050. The Jeffries paid for the first script with a well-timed tax return and have set up a Givealittle page to help fund repeat scripts.

The issue is back in the spotlight after outgoing Council of Trade Unions president Helen Kelly, who has terminal lung cancer, pleaded for the Government to improve access to medicinal cannabis.

She said it's good for Zoe Jeffries' family that she is allowed to use Sativex but points out that they had been trying for ages to get the drug.

"It's going to cost them $1,000 a month to buy the product, a product that we can make here, grow here and that hundreds and hundreds of other people are unable to get."

She has said it's a pretty inefficient and ineffective way of making a drug, which doctors think won't hurt the girl, available to a single person.

"We have got to get over this stigma that's been associated with this drug. It's now being used throughout the world actually, including in Australia for medicinal purposes."

Helen Kelly says the more the Government has to approve individual cases, the more hypocritical it looks.

Kelly has admitted using illegal cannabis oil as a painkiller.

But Associate Health Minister Peter Dunne has rejected calls to allow the use of raw cannabis for medical reasons, saying the Government's policy was "not to decriminalise the cannabis leaf", while there was not sufficient evidence for its medical value in an unprocessed form.

The Australian Government wants to make it legal to grow medicinal cannabis this year. Victoria and NSW state governments have indicated they want to legalise medicinal cannabis and are waiting on a federal regulatory scheme to do so.