Many studies have suggested that cannabis is an effective treatment for neuropathic pain. Advocates have been saying it for years. But a new study from the University of New Mexico is one of the most conclusive yet. It found that “full-spectrum” whole-plant hemp oil greatly reduced pain in mice.

In the study, published in the journal Life, the researchers wrote that in some cases, “full-spectrum” extracted hemp oil had the effect of “reducing mechanical pain sensitivity over tenfold.” 

A tenfold reduction in pain is a significant amount of pain reduction. In a news release about the study, researchers noted that hemp oil proved so effective that some mice experienced pain sensitivity on par with control mice who had no pain issues and received no treatment at all.

The University of New Mexico study is the first to measure the therapeutic potential of legal hemp oil with low THC levels. In the news release, co-researcher Dr. Jacob Miguel Vigil, associate professor in the school’s Psychology Department, said that cannabis plants with low levels of THC offer “profound and often immediate relief from symptoms such as pain, anxiety, and depression.”

The decision to make hemp legal spurred researchers to start the study.

The researchers focused on hemp oil because Congress made hemp sales legal nationwide in the 2018 Farm Bill. This decision marked “a monumental milestone in the history of cannabis prohibition in the United States,” the University of New Mexico researchers wrote.

That’s because it legalized the production, market trade, and consumption of hemp, something not done nationwide since cannabis prohibition started in the 1930s. Hemp legalization happened because hemp does not contain high amounts of THC, the chemical in cannabis that causes the high. Also, because U.S. Senate President Mitch McConnell has many hemp-producing farms in his home state of Kentucky.

Anecdotal evidence of the benefits of hemp oil has been around for years. But researchers wanted to investigate its applications to pain because so little research has been done in the United States. That’s because the federal government has limited testing up to this point.

In the news release, researchers also noted that hemp’s legalization gives U.S. citizens access to a “natural, effective and relatively safe alternative option for treating chronic pain” as opposed to opioids. Opioids have become one of the leading forms of preventable death in the country. The opioid epidemic has prompted many people to question why opioid painkillers are legal but marijuana isn’t.

Researching mice is advantageous because humans have a preexisting bias.

The University of New Mexico researchers used mice in the experiment. They noted that using animals in such an experiment actually has benefits over human clinical trials, because of human bias against marijuana, expectancy effects, and perceptual and cognitive reactions that can occur with people who enroll in a cannabis-themed experiment.

To produce pain in the mice, the researchers used postoperative neuropathic pain equivalent to several years of chronic pain in human clinical patients. But for several hours after cannabis consumption, mice experienced a substantial decrease in pain. In some cases, they experienced almost no pain at all during this period.

The researchers found that the “entourage effect” contained in full-spectrum hemp oil is key to its pain management properties. Every cannabinoid—CBD, CBN, THC—works in harmony. Researcher Jegason P. Diviant said in the news release that “hemp plants contain numerous therapeutic constituents that likely contribute to analgesic responses, including terpenes and flavonoids, which in theory, work together like members of a symphony.”

The researchers said more research is needed on the long-term impact of using hemp oil for pain, as well as human trials. But Vigil said the current study’s findings are part of an “extremely exciting time in modern medical discovery because the average citizen now has legal access to a completely natural and effective medication that can be easily and cheaply produced, simply by sticking a seed in the ground and caring for it as you would any other important part of your life.”