Tasmanians will be able to apply to access medicinal cannabis from Friday, but doctors and advocates have concerns about how the scheme will work.

East Tamar mother Lyn Cleaver uses medicinal cannabis to treat her 26-year-old son Jeremy's seizures.

She has applied to access Tasmania's Controlled Access Scheme but there are no guarantees and no answers about when the medication will be available.

"It's first the medication that we've given Jeremy that comes side-effect free, which is remarkable."

"In order to keep Jeremy safe we will have to continue to break the law, and we won't be alone."

Health Minister Michael Ferguson said the controlled-access scheme is on time, as promised.

But he could not say exactly how long it will take patients to access the drug.

"That will have to rely upon the comprehensive clinical work, between their patient and specialist."

Nicole Cowles from Hobart won't be taking part in the scheme.

Ms Cowles has been treating her daughter Alice's seizures with medicinal cannabis for four years.

She believes the scheme will end up being too restrictive, and the waiting lists will blow out.

"There are so many seriously ill and chronically ill patients who deserve the right of access to a medication that can relieve their suffering," she said.

'Medicinal has become political cannabis'

Doctors said in reality, prescribing medicinal cannabis will be restricted to two rare forms of childhood epilepsy.

They're worried they'll be left to deal with angry patients, for whom the scheme won't deliver.

"Doctors feel overwhelmed because the evidence really is very limited, when it comes to medicinal cannabis," Dr Bastian Seidel said.

"We really believe it is not medicinal cannabis, it has now become political cannabis, where politicians are now feeling they have to make medicinal cannabis legal, no matter what."

Mr Ferguson said unlike other states Tasmania's access scheme does not restrict access to any particular condition.

"As I have made it clear, the pathway is not disease-specific, however we have placed the resource anticipating extra referrals paediatric epilepsy."

Dr Seidel is also concerned the scheme is fragmented.

GPs are required to refer patients to a specialist, who then applies to the secretary of the Health Department for a decision.

"It's not going to be good enough just to see a GP, to ask for a referral to be seen by a hospital specialist, never to be seen by a GP again, only to end up in the hospital system," Dr Seidel said.

"We need a common-sense approach."

Dr Seidel said medicinal cannabis legislation is different in each state.

"It is literally all over the place. And we've been calling on the federal government and the state governments to actually work together to have a united framework."

Stuart Day, President of the Australian Medical Association in Tasmania, supports the new scheme.

"There is some evidence in certain conditions that it may improve the care for patients," he said.

Mr Ferguson said no one would be excluded from the process. The Tasmanian Government said medicinal cannabis will be imported from overseas.

It will be subsidised by the State Government, meaning end users will pay about $40 a month.