Scientists On Marijuana's Health Benefits: We Need More Evidence

By Paul Fuhr 07/27/18

"We don't have evidence about many things marijuana is marketed for and we need to communicate that to the public,” says one doctor.

scientists looking attentively at a computer

Many Americans increasingly believe that marijuana has health benefits, even though there is little to no evidence one way or the other, Newsweek reported.

Over 9,000 U.S. adults participated in an online survey, with 81% responding that weed had at least one medical benefit. From treating diseases like epilepsy and multiple sclerosis to providing some measure of relief from anxiety, stress or depression, the majority of Americans feel the drug is medically valuable.

Not so fast, scientists say.

“The public seems to have a much more favorable view [of marijuana] than is warranted by the current evidence,” the University of California San Francisco’s Dr. Salomeh Keyhani said in a study published in the Annals of Internal Medicine.

Interestingly, because the Drug Enforcement Administration (DEA) categorizes weed as a Schedule I substance (alongside heroin and MDMA), researchers are limited in being able to research it at all.

“[People] believe things that we have no data for,” Keyhani cautioned. “We need better data. We need any data.”

In the absence of empirical data, she suggests, Americans are coming to their own conclusions about the drug.  

“Cannabis is useful for neuropathic pain; it might be useful for nausea and vomiting for cancer and HIV, anorexia, and it might have use in refractory epilepsy in children, but those are very narrow indications," Keyhani told MedPage Today. “We don't have evidence about many things marijuana is marketed for and we need to communicate that to the public.”

A 2017 Gallup survey reported that 45% of U.S. adults have tried marijuana once, while other surveys indicated that 22% of Americans regularly use it. With weed now legal in over half of the U.S. for medicinal purposes, marketing is becoming a huge factor in public perception, Keyhani observed.

“It’s a multi-billion dollar industry, not regulated to the extent of tobacco or alcohol,” she said. “It seems every state is developing a regulatory structure itself. The conflict between federal law and state law has left an open space commercial entities can exploit.”

Despite widespread support for marijuana, the survey revealed that 91% of Americans believe it carries risks. (Only 9% believed the drug has no risks.) The survey yielded some surprises, too:

  • 37% of Americans thought edible marijuana could prevent health problems. 
  • 50.1% agreed that marijuana was “somewhat addictive.”  
  • 25.9% said it was “very addictive.” 

The average age of participants was 48 (“64% were white, 12% were black, 16% were Hispanic, and 8% were of other races”).

Mount Sinai’s Yasmin Hurd said the results aren’t surprising so much as they highlight “the fact that scientists and clinicians don’t publish their studies in newspapers, so the general public isn’t really aware of the scientific evidence that might run counter to their beliefs.”

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Paul Fuhr lives in Columbus, Ohio with his family and two cats, Vesper and Dr. No. He's written for AfterParty MagazineThe Literary Review and The Live Oak Review, among others. He's also the host of "Drop the Needle," a podcast about music and addiction recovery. More at You can also find Paul on Linkedin and Twitter.