You don’t need me to tell you that CBD (cannabidiol) is everywhere. You can eat it, you can drink it, you 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.
Personally, I always keep a few jars of it at my desk to help with the shoulder and neck muscle tension inherent in a job consisting mainly of typing and holding a phone next to my face. But it turns out that the research behind these claims is pretty sparse, to say the least. Here’s what you need to know before you give topical CBD a try.
What is CBD?
Cannabidiol, commonly referred to as CBD, is a cannabinoid, a type of compound found in cannabis (marijuana). Unlike the more well-known cannabinoid THC (tetrahydrocannabinol), CBD does not produce a high.
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 studypublished 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.
The only thing that comes close is a Phase 2 clinical trial using a proprietary CBD transdermal gel (meaning it’s meant to go through the skin into the bloodstream) in 320 patients with knee osteoarthritis over 12 weeks, which has not been peer-reviewed to date. Unfortunately, in almost all of the study’s measures of pain, those who received CBD didn’t have statistically different scores from those who got placebo. But “they found some reductions in pain and improvements in physical function,” Boehnke says.
So…is CBD cream just an expensive placebo?
It’s totally possible (and actually pretty likely) that any effect you get from a commercially available topical CBD product is a placebo effect or related to some other aspect of the product. But there are a few things going on here that are more complex than they seem.
First off, we don’t know much about the correct dose of CBD needed for a pain-relieving effect. The doses in the rat studies that were effective were pretty large (for a rat, obviously). And the human participants in the Phase 2 clinical trial we mentioned received 250 mg of synthetic CBD topically per day—as much as many consumer topical CBD products contain in a single jar.
And even though the lotion was applied topically in the rat study, it wasn’t applied locally to the knee. Instead, the researchers were really using the topical application to get it into the rats’ bloodstream, or what’s called systemic administration. But you’d likely need a different dose for it to be effective locally (if you applied it just to your aching shoulder, for instance) in a human. We have no idea what that dose should look like.
One major issue is that it’s actually somewhat difficult to create a topical cannabinoid product (containing CBD or THC) that penetrates the skin enough to produce an effect, but not so deep that it gets into the bloodstream, Boehnke explains. If the product does get into the bloodstream—if it’s transdermal rather than truly topical—it could potentially reach the brain, possibly producing psychoactive effects if it contains THC.
But at this point, we have no idea how deep the commercially available creams are penetrating. And even if they’re getting to that sweet spot in your skin, we don’t know how much CBD is getting there or how much is necessary to provide an effect.
Nevertheless, how do we account for all the people out there (like me) who use these products and feel like they’re doing something? Beyond the placebo effect, it’s possible that something else in the cream could be doing the heavy lifting here. These products don’t just contain CBD, Dr. Tishler points out. In fact, many of them also come with ingredients like arnica, menthol, or camphor, which may all provide a more immediate sensation of soothing or pain relief. So it could be those ingredients (or just the act of massaging the balm into your skin) that makes you feel better.
Two other common reasons people take CBD are to manage anxiety and sleep issues, two things we know can contribute to pain, Boehnke says. If you’re dealing those kinds of issues in addition to pain, any reduction in pain you feel could be an indirect effect of it helping you manage anxiety or sleep. (But those are still unlikely to be affected by a topical formulation.)
If you (like me) feel like your CBD cream is truly having an effect, it’s likely unrelated to the CBD itself. And because there are plenty of other pain management options out there that we know more about—including medical cannabis—it’s important to talk to a health care provider to make sure you’re not overlooking something else that might be more helpful.
“If somebody comes in with pain, do you reach for a bottle of CBD? The answer is absolutely not,” Dr. Tishler says.
But, ultimately, if you like it, you’re not experiencing bothersome or dangerous side effects, and feel like it works, that’s what matters most.
Consider this before you buy a topical CBD product:
The first thing to be aware of is the amount of CBD that a product claims to contain. Because the studies we have about CBD and pain all looked at systemic administration rather than truly local, we don’t really know what the correct dose would be when applied locally. It’s tempting to go for the highest amount you can find, but it’s really up to you since we don’t even know where to start.
It’s also important to remember that, although generally benign, side effects have been reported with some forms of CBD. For instance, oral CBD taken in the large amounts that have shown some limited promise in helping with anxiety issues may come with side effects, such as diarrhea, reduced appetite, fatigue, and interactions with other drugs you might be taking, specifically blood thinners, Cooper says.
But some studies have found essentially zero side effects of high-dose CBD (900mg) and those that researchers do see—like drug interactions—aren’t considered to be issues when CBD is used topically.
If you’re worried about a purely topical CBD product getting into your bloodstream, Dr. Tishler explains that’s unlikely. CBD is hydrophobic (meaning it isn’t water-soluble) and lipophilic (attracted to lipids, like oils) and tends to stay on the outer layer of skin or possibly accumulate in the sebaceous glands unless it’s paired with “enhancers” (ingredients designed to help them make it through the skin, at which point they would instead be transdermal). Making a truly “water-soluble CBD” has been a challenge for the industry, although there are a variety of patents out there.
That said, we don’t always know exactly what’s in the CBD products out there due to a lack of regulation. Until recently, CBD was regulated as a Schedule 1 substance, meaning that the federal government believed it had a high potential for abuse and no accepted medical value. But the FDA approval of Epidiolex last year and the passage of the Farm Bill in December 2018 changed things by lifting the federal ban on commercial hemp production (hemp also contains CBD in lower amounts than cannabis). But it also made things more confusing because we’re still waiting on actual CBD regulations from the FDA. In the meantime, companies are treating hemp-derived CBD as if it’s perfectly legal, Dr. Tishler says.
The lack of regulation has also left the door open for products to be subject to both “contamination and adulteration,” Dr. Tishler says. One , published in JAMA in 2017, found that almost 70 percent of CBD products—including vape cartridges, tinctures, and oils—sold online did not contain the things they claimed to in the right amounts. That’s why Boehnke recommends only buying CBD products that you can verify (via a certificate of analysis) do contain what they’re supposed to. And Boenhke offers the same advice he does for all cannabinoid products: Start at a low dose and, if you decide to increase it, go slowly. (Start low, go slow.)
Ultimately, though, I still love my CBD creams and don’t plan on abandoning them any time soon (I also love my bottle of ibuprofen, for the record). But if you’re interested in turning to CBD to manage serious pain, it’s probably worth talking to your doctor about all of your options first.