CBD (cannabidiol) is pretty common nowadays, you can eat it, can drink it, can vape it, you can even bathe in it. And although there’s still plenty to learn about this fascinating little compound, fans of it claim that it has some pretty impressive benefits—particularly when it comes to managing pain.
CBD, short for cannabidiol, is a trending ingredient the natural products industry and is the focus of a new area of cannabis research. CBD is one of many cannabinoids, or molecules produced uniquely by the cannabis family. Unlike tetrahydrocannabinol (THC, the primary psychoactive element in marijuana), CBD is non-psychoactive, meaning it doesn’t have a strong effect on cognitive brain activity and doesn’t cause the “high” associated with marijuana.
Both THC and CBD act on a system of receptors in your body called cannabinoid receptors. You have cannabinoid receptors throughout your body and, so far, researchers have identified two major types: CB1 (found primarily in the central nervous system, including parts of the brain and spinal cord) and CB2 (found mainly in immune system tissues). Interestingly, both have been found in skin. Researchers have also found that while THC can bind to and activate both types of receptors, CBD seems to modulate and somewhat block the effects of CB1 and CB2 receptors. So, any effect that CBD has on CB receptors may actually be more related to regulating and even counteracting some of the actions of THC and other cannabinoids in the brain.
Why does the body have receptors for compounds in cannabis? Well, it doesn’t exactly. Cannabinoids like THC and CBD are similar enough to compounds that your body naturally makes, called endocannabinoids, that they can interact with this system. Normally, the endocannabinoid system is thought to play a role in a variety of functions in the body, helping to regulate things like parts of the immune system, the release of hormones, metabolism, and memory.
If you’re ingesting something that only has CBD in it and no THC, you won’t have significant effects in the brain. This is why CBD is often referred to as being “non-psychoactive,” although that’s clearly a bit of an oversimplification because it does do something to the central nervous system.
More recent research suggests that many of CBD’s effects may occur outside of CB receptors, Jordan Tishler, M.D., medical cannabis expert at InhaleMD in Boston, tells SELF. In fact, according to a recent review published in Molecules, CBD may have effects on some serotonin receptors (known to play a role in depression and anxiety), adenosine receptors (one of the neurological targets for caffeine), and even TRPV-1 receptors (more commonly associated with taste and the sensation of spiciness).
“It actually is a very promiscuous compound,” Kevin Boehnke, Ph.D., research fellow in the department of anesthesiology and the Chronic Pain and Fatigue Research Center at the University of Michigan, tells SELF. “It will bind to receptors in multiple different pathways,” which makes it difficult to know how it might cause noticeable effects.
“Cannabidiol is a super messy drug,” Ziva Cooper, Ph.D., research director of the UCLA Cannabis Research Initiative in the Jane and Terry Semel Institute for Neuroscience and Human Behavior and the department of psychiatry and biobehavioral sciences, tells SELF. “It has lots and lots of targets and it’s not clear how much of its effects on each target contribute to the potential pain relieving effects.”
All of this points to how hard it is to study the specific effects of CBD on its own—which might be why it’s tempting to claim that it’s the cure for everything without a whole lot of research to actually back up all of those claims.
Here’s what the research says about using CBD for pain.
The most common medical reason for which people report using CBD is to manage chronic pain, followed closely by managing arthritis or joint pain. But does it actually work?
When the National Academies of Sciences, Medicine, and Engineering evaluated decades of cannabis research, they concluded that “in adults with chronic pain, patients who were treated with cannabis or cannabinoids are more likely to experience a clinically significant reduction in pain symptoms.”
But that’s not quite as exciting for CBD as it sounds: “We don’t know cannabidiol’s effects on its own,” says Cooper, who was part of the National Academies committee that put together this report. “[The conclusions about cannabis and cannabinoids] were based on what we know about THC or THC plus cannabidiol.”
In fact, the most compelling research they found for using cannabinoids for pain came from a large review and meta-analysis published in JAMA in 2015. For the study, researchers looked at results from 79 previous studies of cannabinoids and various medical conditions, including chronic pain. However, of those studies, only four involved CBD (without THC)—none of which were looking at pain. So although we might assume that CBD is doing something to help address pain—according to the studies involving the whole cannabis plant—we don’t have great evidence to prove it.
“It might be that cannabidiol by itself is helpful for pain, but at this point we don’t know that,” Cooper says.
The studies we do have about CBD for pain are all animal studies. For example, in a 2017 study published in Pain, researchers gave rats an injection into one of their knee joints to model osteoarthritis. Rats then either received doses of CBD or saline directly into an artery in the knee joint. Results showed that, after receiving CBD, rats showed less inflammation in the joint area and fewer pain-related behaviors (like shaking or withdrawing the affected paw or not being able to bear weight in that paw) compared to those that received saline.
Another study published in 2016 in the European Journal of Pain also looked at arthritis in rats but did so with a topical formulation of CBD. After the rats received an injection into one knee joint to model arthritis, they received a gel that contained either 10 percent CBD (in four different total amounts) or 1 percent CBD (the control) on four consecutive days. The gel was massaged into the rats’ shaved backs for 30 seconds each time.
Then the researchers measured the inflammation in each rat’s knee joint, the level of CBD that made it into their bloodstream, and their pain-related behaviors. They found that the rats that were given the two highest doses of CBD showed significantly lower levels of inflammation and lower pain behavior scores compared to those that got the control. The two lower doses didn’t show much of an effect.
But if you’re reading this, you are probably not a rat, which means these results aren’t directly applicable to your life. Although we know that rats do share much of our physiology—including CB1 and CB2 receptors—these studies don’t really tell us if humans would have the same results with CBD.
“There’s really no substitute for doing proper human studies, which are difficult, expensive, and ethically complicated,” Dr. Tishler says. And we simply don’t have them for CBD and pain.