Two New Brunswick doctors are speaking about the challenges of prescribing medical marijuana.

Since April, it can be prescribed by any licensed physician with just a simple form, but few doctors are prescribing it in the province.

The medicine has shown promise for helping people suffering from conditions including multiple sclerosis and Parkinson's, but because marijuana has been illegal for so long, there are few formal studies that doctors can rely on.

The College of Physicians and Surgeons is working on a set of guideline, but for now doctors are largely on their own.

Prescription doesn't include potency

Both Dr. Colleen O'Connell and Dr. Doug Smith specialize in physical medicine and rehabilitation, and both are prescribing medical marijuana.

A physician must indicate the amount of drug on the prescription, but they don't have to indicate strength. Potency can vary depending on the strain of the plant.

"They can make decisions on their own, so it's sort of a weird place to be as a physician; it's not like anything else you can prescribe," O’Connell said.

Imagine a doctor writing a prescription: "Provide them with opiods. Let them choose how strong." - Dr. Colleen O'Connell

"I stick to the quantity that I am more comfortable with based on what research has been done, which is that one to three grams per day. If a patient is using it to bake a product, they're probably using more up front. If they're using it purely as inhalation, they're probably using less."

Dr. Doug Smith agreed it’s a murky process.

"It's probably an area that causes physicians a high level of anxiety," he said.

"I go by what the patient is reporting. And patients do have to go by a trial and error method of [tailoring] a dose to their own requirements."

O’Connell said that creates problems.

"Imagine the doctor writing a prescription: 'Provide them with opiods. Let them choose how strong.' So we need more guidance. And what is needed is more research around that," she said.

Getting patients off OxyContin

Dr. Ed Schollenburg of the New Brunswick College of Physicians and Surgeons acknowledged the confusion.

"Most physicians aren't sure what they should do, when they should use it, what the dose should be. There are guidelines being developed on that, but it wasn't really that you could find an easy source that was beyond question," he said.

Doctors Smith and O’Connell prescribe it because they’ve seen it work.

Smith said in 2008, he saw a patient who had previously been mumbling incoherently, and on huge doses of OxyContin.

"Here was a totally different looking man saying he was using marijuana and was off all of his OxyContin. It was pretty hard to say no to something like that," he said.

O'Connell said the initial studies she has been part of are all showing positive results.

"The vast majority did find it effective for managing their pain as well as their sleep," she said.

"I've had probably more patients benefit than not for those who we have moved forward for the prescriptions."

No deaths from marijuana

The doctors say marijuana has no recorded overdose deaths and stacks up well against other drugs used for chronic pain, many of which can cause unpleasant side-effects.

Both agree that it's not for everyone. And O'Connell has a caution to all doctors and patients.

"It needs to be just like any other thing you do for an intervention. Is it working? Are you having a functional benefit? Is it making a difference in your life? Are there adverse events? And this needs to be monitored and followed," she said.

Smith has been asked to speak about marijuana to doctors at the Moncton Hospital in the spring. O'Connell is part of a new study measuring the effects of inhaled cannabis on patients with spinal cord injuries.

Both hope the new guidelines will bring clarity to the issue.