Medical cannabis may have the potential to help wean opioid users addicted to the deadly drugs, new research shows.

The review of previous research found early evidence that medical marijuana might help with treatment for mental health issues such as post-traumatic stress disorder (PTSD) and substance abuse disorders.

The study published in the latest issue of the Clinical Psychology Review journal, looked at all the studies involving mental health and marijuana published since 1960, and found many people were substituting opioids for cannabis.

"Research suggests that people may be using cannabis as an exit drug to reduce use of substances that are potentially more harmful," the study’s lead author, Zach Walsh, a psychologist and marijuana researcher from UBC’s Okanagan campus, said in a statement.

Greg Miller is one of those people. He had struggled with drug and alcohol abuse after a car accident left him with chronic pain. But he then replaced it with medical marijuana and had success at managing his pain without the use of morphine and alcohol.

“It helps me control my pain issues,” Miller told CTV Vancouver.

Walsh told CTV Vancouver: “If [cannabis] is reducing the use of a more harmful substance than it has public benefit.”

A potential public benefit might be a possible solution to the opioid crisis that has led to the deaths of hundreds of Canadians and hospitalized thousands more.

Health Minister Jane Philpott is hosting a summit in Ottawa starting Friday to discuss possible solutions to the opioid crisis.

While the Centre for Addiction and Mental Health (CAMH) has already suggested restricting prescriptions for high-dose opioids, Walsh argues that the system needs to offer a viable alternative.

“We can’t just say opioids versus no opioids, we have to be able to offer a compassionate solution for people who are suffering and for some people it looks like there may be a role for cannabis,” he said.

Although, the review cautioned that people suffering from bipolar disorder and psychosis should avoid the drug.

Addictions counsellor Roy Dockrill doesn’t think cannabis should be used as a substitute as keeps some people from dealing with the root cause of the substance abuse.

“You’re just trading addictions,” said Dockrill. “By clouding our judgement with substances, alcohol, drugs or whatever, it’s still not a true life experience.”

More clinical research is needed to understand how and why cannabis is used as a substitute as well as if it is the best alternative.

"We're trying to clear some of the smoke if you will," said Walsh.

With a report from CTV Vancouver's Kent Molgat