Researchers surveyed 16,280 people in the U.S. and found that 81 percent of respondents believe that smoking marijuana has at least one health benefit, with pain management being the most commonly cited one.
Yet a separate study spanning four years found no evidence that marijuana use improves the symptoms of chronic pain.
The survey also found that 91 percent of respondents believe that marijuana has at least one risk, but the most commonly cited risk — legal trouble — wasn't health related, a finding researchers found troubling because it indicates that many people are downplaying potential harm, according to Dr. Salomeh Keyhani, a professor of medicine at UC San Francisco.
“The American public has a much more favorable point of view than is warranted by the evidence,” Dr. Keyhani told Reuters. “Perhaps most concerning is that they think that it prevents health problems.”
The survey found that 18 percent of respondents believe that smoking marijuana is somewhat or completely safe for adults.
In addition, nearly half of those surveyed believe that marijuana can alleviate insomnia, anxiety and depression, none of which are scientifically established, says Dr. Keyhani.
"The bottom line is that there's no evidence for the vast majority of this," Dr. Keyhani told Livescience. "There's limited data on harm, and people think that means it's OK."
Researchers created the survey to examine the impact of marketing on the public's perception of marijuana. From the Guardian:
Mixed signals regarding marijuana’s potential dangers and benefits have enabled the commercial marijuana industry to promote a maximalist view of marijuana’s possible benefits. Since direct unproven claims of marijuana’s medical benefits, and assertions such as that a product cures cancer, can lead to unwanted attention from the FDA regulators, cannabis companies have learned to be much more subtle.
Despite the federal ban on marijuana, the Food and Drug Administration recently approved Epidiolex, an epilepsy drug derived from marijuana. Medical marijuana is also legal in 31 states, a fact that only contributes to its rosy reputation.
Still, Keyhani says more research needs to be done. Until that happens, most of the health claims touted by the industry remain unproven.
“We need better data,” Keyhani told the Guardian. “We need any data.”