A new systematic review and meta-analysis published in a respected journal show that marijuana is no different than a placebo in treating pain. I consistently read anecdotal claims that somehow cannabis and its derivatives are useful. in treating pain, but when I looked at the evidence, it appeared that there really wasn’t anything there.
Pain management is one of the most common reasons people report using medical cannabis. According to a US national survey, 17% of respondents who had reported using cannabis in the past year had been prescribed medical cannabis. When it comes to self-medication, the numbers are even higher – with estimates that between 17-30% of adults in North America, Europe, and Australia report they use it to manage pain. But does this mean that there is evidence that it actually works for reducing pain?
Real scientists decided to look at the same claims about marijuana and pain and have come to the same conclusion — there’s not much supporting evidence. Now I know the comments section will be filled with people that want to tell me how cannabis is a miracle drug for pain and should replace opioids. But I am one who only follows the evidence, and it’s seriously lacking.
Like I always do, we’re going to take a look at this study and see what it tells us about marijuana and pain.
Marijuana and pain paper
In a systematic review and meta-analysis (considered the top of the hierarchy of biomedical research), published on 1 November 2022 in JAMA Network Open, Karin Jensen, Ph.D., of the Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden, and colleagues examined 20 studies of 1459 individuals. The researchers examined the results of randomized controlled trials in which cannabis was compared with a placebo for the treatment of clinical pain. They specifically included studies that compared the change in pain intensity before and after treatment.
The studies included a variety of different pain conditions, such as neuropathic pain, which is caused by damage to the nerves, and multiple sclerosis. They also reviewed types of cannabis products – including THC, CBD, and synthetic cannabis (such as nabilone). These treatments were administered in a variety of ways, including via pill, spray, oil, and smoked.
The majority of the study’s participants were female (62%) and aged between 33 and 62. Most of the studies were conducted in the US, UK, or Canada, although they also included studies from Brazil, Belgium, Germany, France, the Netherlands, Israel, the Czech Republic, and Spain. Demographically, this is a fairly broad sampling.
Here are the key results:
- The results showed a significant pain reduction in response to placebos in randomized clinical trials compared to cannabinoids.
- Trials with a low risk of bias had greater placebo responses to pain reduction compared to cannabinoids.
This study also is in line with the results of a 2021 meta-analysis. This 2021 meta-analysis also found that higher-quality studies with better blinding procedures (where both participants and researchers are unaware of who is receiving the active substance which can be difficult with the unique smell and taste of cannabis) actually had higher placebo responses. The results of this study imply that without proper blinding, marijuana may have artificially higher results in treating pain.
Why the strong placebo response?
The researchers wanted to dig into why there might be such a powerful placebo response in these clinical trials. The researchers examined the way the clinical studies were covered by the media and academic journals to see whether they related to the therapeutic effect participants reported. Previous research has shown media coverage and information on the internet can affect the expectations that a person has of a treatment.
In other words, trial participants may enter the trial with high expectations that it will work contributing to the placebo effect. The participants, as long as the trial is properly blinded, will just assume that the medication they are taking will work on pain.
If a person thinks they will experience relief from their pain by using a certain product or treatment, this can change their perception of incoming pain signals. It makes them think their pain is less severe. The placebo effect may be so powerful that it works even if the patient is presented with evidence that contradicts their expectations.
I think this systematic review and meta-analysis busts the myth that marijuana is an effective drug for pain treatment. However, placebo responses, especially for pain, can be a very powerful tool for medicine.
I think the most important point is that a sugar pill is more powerful than cannabis in treating pain, as long as the patient believes that the placebo is actually the drug.
I know a lot of people try to justify the use of or the availability of cannabis with medical rationalization. However, for pain relief, it does not appear to have a clinical benefit beyond a placebo response. In fact, in these studies, the reduction in pain was higher with the placebo, which could indicate that cannabis has a negative effect on pain management — we would need more research to test that hypothesis.
I am agnostic about the use of marijuana recreationally. If you want to get high, go for it. But making medical claims like “it cures cancer” (it doesn’t) or “reduces pain” (the research says it doesn’t) just bothers me — I think the medical claims for marijuana are vastly overstated.
But I’m not opposed to the placebo effect. But sugar pills are a lot less expensive than cannabinoid pills.
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