Veterans who use medical marijuana to treat post-traumatic stress disorder are having to go outside the network of clinics sanctioned by Veterans Affairs to get the drug due to concerns by doctors at the clinics about its effectiveness.

The last operational stress injury clinic to prescribe medical marijuana to former soldiers stopped doing so in January, citing a lack of research and concerns it might even be doing more harm than good.

"The physician's Hippocratic oath is that above all you should do no harm," said Dr. Anthony Njoku of the OSI clinic in Fredericton.

"These are people ... who are struggling. You don't want to be the one who's added on top of that all in the vain attempt at helping them. You then end up making them much worse," he said.

The decision by the clinic to stop prescribing medical cannabis is mentioned in an undated briefing note prepared for the deputy minister of Veterans Affairs and obtained by CBC News under access to information.

The department has struggled with its policy on medical marijuana for veterans. In May, the department lowered the daily limit for medical cannabis prescriptions covered by veterans' benefits to three grams a day, down from 10 grams, after an internal review found reimbursements to veterans for medical cannabis had shot up over the past decade.

The new policy allowed for higher amounts if the patient obtained authorization from a medical specialist.

But with the OSI clinics no longer prescribing cannabis, veterans with mental illnesses have one less place to turn to get a psychiatrist's approval.

Operational stress injury clinics provide assessments, treatment, prevention and support to serving Canadian Forces members and veterans with mental illnesses. The department of Veterans Affairs provides guidance to these clinics but does not get involved in operational issues. They are operated by local or provincial health authorities.

Making it up as they go along

Veterans Affairs, along with the Canadian Forces, are undertaking a clinical trial to evaluate the safety and efficacy of medical cannabis in treating PTSD.

But for now, Njoku said the research and evidence is scant.

"Overall, we really even now don't have that much research work that has been done to determine either the dosing, to determine the efficacy, to determine which kind of clients would best benefit from this," he said.

"We're making it up as we go along unfortunately," he said.

That reason isn't good enough for veteran Fabian Henry.

"It's not fair, it's just not fair that we don't have a place to go, those who choose medicinal marijuana," he said. "I have to look for outside help, other than the operational stress injury clinic."

Henry served in the Canadian Forces for 12 years and was medically released after being diagnosed with post traumatic stress disorder in 2012. Now he's the founder of Marijuana for Trauma, a company with 15 locations to help veterans access medical marijuana across the country.

He uses marijuana to relieve his PTSD symptoms.

Fabian Henry says it's unfair that he and other veterans cannot get medical marijuana prescriptions from Veterans Affairs-sanctioned clinics. (CBC)

Henry said now that the clinic in Fredericton no longer writes prescriptions or fills special requests of veterans for amounts beyond the limit of three grams of dried cannabis per day, it's next to impossible for him to get the seven grams of marijuana he said he requires to cope with his symptoms.

"When they cut my medicine back, I started to fear for my health, those around me, my community, because before all of this I was not a good person.... I didn't want to go down that road again," he said.

Limited access

Veterans are able to access medical marijuana for mental-health illnesses from physicians outside of the Veterans Affairs network. Henry said that if someone does not need more than three grams, access is getting better because of groups like his.

In an email to CBC News, a spokesperson for Veterans Affairs said operational stress injury clinics are run by provincial health authorities and the department does not have the "authority to direct any health care professionals to authorize specific treatments."

The department reimbursed 5,190 veterans for medical cannabis between April 1 and July 31, 2017. As of Aug. 29, the department had received 637 requests for reimbursement of more than three grams per day since November 2016.