The Canadian Medical Association is worried that as large medical marijuana grow facilities get federal licences, more patients will be clamouring for a drug many doctors are uncomfortable prescribing.

Starting April 1, medical marijuana users in Canada will no longer be able to grow their own. Instead, they'll have to get pot from producers licensed by Health Canada.

Darryl Hudson with medical marijuana plants

Darryl Hudson, chief research officer at Peace Naturals, says his company's goal is to relate different plant varieties to specific ailments with standardized doses. (Kim Brunhuber/CBC)

When the change was announced in June, Health Canada said the number of people authorized to use marijuana for medical reasons grew from less than 500 in 2001 to more than 30,000. The department will no longer be a supplier, and it says the change will provide access to quality-controlled marijuana for medical purposes that is produced under secure and sanitary conditions.

Selected changes to medical marijuana access

Health Canada's website provides information for clients, licensed providers, doctors and nurse practitioners, police and municipalities. It covers everything from what documents clients need during the transition period, to the personal and physical security clearances for providers, to the medical document itself that health professionals fill out.  
 
For example licensed producers can only provide dried marijuana, storefronts are not allowed, and the "Authorization to Possess" will no longer be valid after April 1, 2014. 
 
Key dates 
 
June 19, 2013: Announcement of new regulations to govern the use of medical marijuana formally published. 
 
March 31, 2014: Old (Marijuana Medical Access Program) and new access systems run concurrently until this date. All licences for individuals and designates expire. 
 
April 1, 2014: New Marijuana for Medical Purposes Regulations take full effect. Health Canada will no longer sell and distribute marijuana for medical purposes. All personal and designated production no longer permitted and holders must safely dispose of all dried product and plants. The only legal source to obtain marijuana for medical purposes is from licensed producers.

Mark Gobuty, CEO of Peace Naturals in Clearview Township, south of Collingwood, Ont., is proud of his medical cannabis facility, where some plants are half way through their flowering cycle. The products will be dried out and then sold to clients.

"There's still a lot of giggle factor," Gobuty acknowledged.

He said doctors can sign a letter for patients to get a small amount of marijuana and then get feedback from the patient and the company.

At Peace Naturals, the ultimate goal is to come up with standardized medications from different plant varieties for specific ailments, such as pain, nausea or insomnia, said Darryl Hudson, the company's chief of research.

While a doctor's prescription states an exact amount of drug to be taken at exact times for an exact length, the new system gives physicians permission to say they think it's OK for a specific patient to use marijuana, said Dr. Louis Francescutti, president of the Canadian Medical Association.

"We're asking them to prescribe a product that really has not been tested as rigorously as any other product that's out there and basically writing it with your eyes blindfolded and assuming all the risks that go with it."

Francescutti also has concerns about marijuana's potential dangers, especially when there are other proven medications for controlling pain and nausea available.

Doctors advised to tread gently

When doctors prescribe other medications, they know the benefits and side-effects. But physicians receive little if any training about marijuana.

"I can tell you as an emergency physician, I will not be prescribing any marijuana simply because I don't feel safe that I know exactly what I'm prescribing," Francescutti said.

Regulatory colleges and medical liability experts are also advising physicians to tread gently until the medicinal benefits of marijuana are clearly shown.

There are clinical trials that have demonstrated that cannabis can help with some illnesses and conditions, but they are relatively small in number and short in duration, said Dr. Mark Ware, a professor in family medicine at Montreal's McGill University. He oversees a program where 30 to 40 patients are using cannabis for severe, chronic pain that hasn't responded to conventional treatments.

"We need to get that knowledge out into the hands of the physicians out in the community who are facing this issue everyday," Ware said. "If we don't, they will continue to put their hands over their ears and wish the whole thing would go away."

The growers, CMA, and Ware all want the federal government to fund more studies.

In the meantime, Ware is asking his colleagues to learn about what evidence there is. To that end, he has started a non-profit organization called Canadian Consortium for the Investigation of Cannabinoids to help educate physicians on the medical benefits of marijuana.

With files from CBC's Kim Brunhuber