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More and more people, young and old, are fast becoming fans of legalized weed, Jeff Sessions notwithstanding. That popularity has been greatly aided by the proliferation of laws that allow it to be used as a medical treatment, not just in the U.S., but in other countries such as Canada, which legalized medical pot in 2001. But Canadian doctors, much like their neighbors to the south, are less enthused than the general public about the bold promises of medical pot.

On Thursday, a panel of 18 experts published new simplified guidelines for when the average doctor should prescribe pot in the journal Canadian Family Physician. Their short answer: Not very often, and not for most of the conditions it’s been advertised to treat.

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The panel reviewed studies and clinical trials that evaluated using medical cannabis to treat everything from headaches to depression. Despite the deep well of research, they overall found that most studies were too small, imprecise, and otherwise flawed to base any solid recommendations on. For many conditions, there aren’t even any randomized, placebo-controlled trials—the sort of studies agencies like the Food and Drug Administration rely on when deciding to approve a drug—to consider as evidence.

“It’s more unfortunate than negative. The problem is that the research just isn’t there for many conditions,” Mike Allan, the lead author of the guidelines, a community physician, and professor of family medicine at the University of Alberta, told Gizmodo. “The number one reason cannabinoids are requested is for pain; the number two reasons for mental health issues, and surprisingly, there’s not a single randomized study of depression, neither is there one for general anxiety disorder.”

“And even when there is research, it’s often quite limited. In the case of social anxiety disorder, there’s one study of 24 people,” he added.

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According to the authors, the short list of conditions that likely seem to be helped by weed include certain forms of chronic nerve pain; muscle spasms caused by multiple sclerosis or spinal cord injuries; vomiting and nausea brought on by cancer treatment; and pain from otherwise terminal illnesses. But even there, the benefits were usually modest at best, and harder still to see with smoked medical weed.

The panel’s recommendations are far from unusual among the medical profession. Organizations such as the American Medical Association and American Society of Addiction Medicine have long noted the lack of good research surrounding the use of medical cannabis, even as they tentatively support doctors and patients having access to it in states where it’s permitted.

Of course, that lack of good research is in no small part due to the fact that governments continue to officially classify pot as an irredeemably dangerous substance with no medicinal benefits at all. It’s this very reticence that led advocates to push for a patchwork, state-by-state approach to legalization in the U.S.—a model that’s proven to be incredibly fragile to the whims of those in power, such as Attorney General Sessions. And while the legalization movement has made it easier for scientists to study pot more recently, they still run into many bureaucratic hurdles.

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Allen says that while this government interference is historically to blame for the lag in pot research, it’s not the whole picture, at least in Canada.

“There’s other complex issues at play here. Most products that are brought to market, they’re brought by industry. And so industry has to perform these kinds of rigorous studies that allow them to market their products...in the case of medical cannabinoids, particularly medical marijuana, it doesn’t have to go through that same process,” he said. “And there was no kind of plan to ensure that would occur when they did come to market in Canada, so there was that missing piece.”

That theoretically shouldn’t be a problem for Canada in the near future. Last November, the country passed a law allowing for the wholesale legalization of marijuana. But there continue to be questions about how and when the rollout will actually be implemented (Not that these delays have stopped dispensaries from starting to illegally offer marijuana to customers, though). The opening of the pot floodgates, Alan hopes, will also allow for better science on medical cannabis to come along as well.

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“I’m hoping some of the funds generated by legalization will go back into medical research. It’d be great if we started to invest in that, so we can sort out these claims better,” he said. “And rather than go at it through tiny little studies, we need to actually do large studies that can determine whether the drugs are really working; what their adverse effects may be. And we need to do these studies well. That’s something that’s very rare.” 

“I hope there will be much better evidence to look at in the near future,” he added.

The new guidelines are expected to be given to some 30,000 clinicians across Canada.

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[Canadian Family Physician]

Update: This article has been updated to include quotes from the lead author behind the guidelines.