When patients have a choice between opioids and medical marijuana for a painful condition, an overwhelming majority say they prefer marijuana, that it works just as well, and has fewer side effects, a new survey finds.

Though the survey , involving 2,897 medical cannabis patients, didn’t track actual drug use or efficacy, the findings fits with previous data. Decades of research suggest marijuana is effective for pain treatment . And recent studies have found that in states with medical marijuana availability, there are fewer opioid overdose deaths and doctors fill fewer opioid prescriptions

The authors of the new survey, led by Amanda Reiman of the University of California, Berkeley, say the data furthers the need to examine marijuana as a “viable substitute for pain treatment,” particularly in light of the devastating opioid epidemic now gripping the country. The Centers for Disease Control and Prevention reports that opioids killed more than 33,000 Americans in 2015, and it estimates that 91 people in the US die each day from the highly addictive drugs.

Though people using marijuana can develop use disorders, it is virtually impossible to die of an overdose— no marijuana overdose deaths have ever been reported to the Drug Enforcement Administration.

“A society with less opioid dependent people will result in fewer public health harms,” the authors of the new study note.

For their survey, the researchers partnered with (but were not paid by) HelloMD, an online community for medical cannabis patients. Of the 2,897 patients recruited for the survey, 63 percent were using marijuana for pain-related conditions, such as fibromyalgia, back pain, and arthritis. About 30 percent, or 841 patients, also reported using an opioid currently or in the past six months.

Of those 841, 92 percent agreed or strongly agreed with the statement that they preferred cannabis over opioids for their condition. And 93 percent agreed or strongly agreed that they were more likely to pick cannabis over opioids if both were readily available. Most also said that cannabis was just as effective at relieving pain as opioids, with 71 percent agreeing or strongly agreeing with the statement. Last, 97 percent agreed or strongly agreed that they could cut down on opioid use if cannabis was available.

The researchers found similar results when they asked about non-opioid pain medication use (see data above).

The survey has limitations. It’s pulling from a self-selected group of cannabis users, for one, so they may be biased. The survey data also doesn’t include actual drug use data or efficacy, just perceptions, which may be skewed.

Researchers need more data to make firm conclusions. But with the data available, the authors suggest that “providing the patient with the option of cannabis as a method of pain treatment alongside the option of opioids might assist with pain relief in a safer environment with less risk.”

Cannabis and Cannabinoid Research, 2017. DOI: 10.1089/can.2017.0012 (About DOIs).