Minister of Veterans Affairs Kent Hehr says he wants answers following a spike in the number of veterans turning to the government to pay for their medically prescribed marijuana.

In 2013-14, 112 veterans were reimbursed for medical marijuana, according to figures provided by Veterans Affairs. The next year, it was 628. Now, in just the first nine months of the 2015-16 fiscal year, it's shot up to 1,320.

"I immediately launched an internal review" after being briefed on the issue in early March, said Hehr.

"The fact that the former government let this program evolve from 2007 onward without a policy, an informed policy based on the wellness of veterans and their families, frankly shocked me."

The federal government sets a limit of how much pot it will pay for: 10 grams a day. What's less clear is why veterans are using medical marijuana, because the department says it doesn't track the underlying conditions behind the prescriptions.

Some veterans say they are using it to help with post-traumatic stress disorder. Sylvain Chartrand, director of the group Canadians Veterans Advocacy, ingests his cannabis via a marijuana butter that he mixes into hot chocolate.

Veterans Affairs Minister Kent Hehr says his department is looking into the use of medical marijuana among veterans to better understand what conditions the drug is being used to treat. (Fred Chartrand/Canadian Press)

"I need it for my PTSD. I don't sleep. For my anxiety. For depression," said Chartrand, who served in Cyprus in 1990 and Bosnia in 1993.

Veterans Affairs isn't involved in prescribing marijuana. Veterans consult their doctor and Blue Cross processes the claims.

However, giving pot to veterans with post-traumatic stress disorder directly contradicts the military's stance on the issue. In a statement, the Canadian Forces said there's not enough proof to authorize marijuana as a treatment for PTSD and that some evidence suggests it could be harmful.

Why the increase?

The veterans affairs minister wouldn't weigh in on what might be behind the growing number of prescriptions.

"I've asked my staff to go about this internal review, look at the use of marijuana for medical purposes, establish what is in the best interest of my veterans."

Chartrand isn't convinced that more prescriptions actually means more veterans are using pot.

"Yes, there's an influx, but people were using it before and just not getting paid for it," he said.

The Conservatives say they're concerned about whether the number of prescriptions is too high and whether it's taxpayer money well spent.

"It's very worrying," said defence critic Pierre Paul-Hus. "What we're doing is we're taking our veterans and saying we're going to give you a joint of marijuana, that's going to help your problems. I don't think it's the solution."

When asked why the previous government didn't take action despite reports of increased use, Paul-Hus suggested the "major" increase in the number of prescriptions is clear now.

The increased claims also come with an increased cost. From April 1 to Dec. 31, 2015, the bill for veterans' medical marijuana added up to ​$12.1 million.

Hehr hopes the internal review will be completed in the next couple of months.