Can cannabis really relieve pain? Or is it just all in our heads? 

New research suggests that cannabis and placebo have similar pain relief effects. In some places where marijuana is legal, people with cancer and other chronic diseases rely on this substance to ease their pain, but a recent study debunked this claim and discovered that this is simply because they believe weed will help. The new research starts a discussion on the actual effectiveness and function of cannabis as a pain reliever. 

What does the new study suggest?

Cannabis, commonly called marijuana, has been used around the world for many years to reduce pain in patients. It is being used to treat certain conditions, such as multiple sclerosis, chronic pain and depression. Cannabis is known to work as a pain reliever by stimulating cannabinoid receptors in the brain which then activates the brain’s reward system and lower pain levels [1]. However, a recent study concluded that the use of cannabis as a pain reliever is merely coming from a belief that it will work on your body.  

In a recent research study published by JAMA Network Open on 28 November 2022, the results show that there is a significant pain reduction in response to placebo in cannabinoid randomised clinical trials. The participants who received a cannabis placebo were found to experience a reduction in pain, despite not having to use the drug. Surprisingly even the patients who did not use the active treatment or the placebo were reported to have the same levels of pain relief [2]. 

The new research further examined twenty studies using cannabis for pain control in 1,450 people who are between the ages of 33 and 62. All the studies were conducted following the double-blind strategy, placebo-controlled clinical trials, which means that even the researchers themselves did not know which study participant may receive cannabis or dummy treatment.

In the end, the researchers concluded that there was no difference in self-reported pain reduction between the use of marijuana or placebo in the clinical trials. In fact, both marijuana and placebo – showed a large improvement in the pain of the study participants. There was no difference between the length of treatment – 45 days or several months – both showed pain improvement as well.

What is the ‘placebo effect’?

The term ‘placebo effect’ was used in the study that pertains to the positive expectations about the dummy pill of marijuana that affects the way the patients look at the procedure or treatment – it’s like tricking the brain into thinking that certain medications that you consumed are what you supposed them to be, tending you to think they are essentially working on your body. During the experiment, the study created a cannabis placebo which is a different substance from marijuana, but it mimics its appearance, smell, taste and feel. The cannabis placebo provides the same pain relief effects as the actual cannabis-based products. 

There are two main cannabinoids in marijuana that were used in the study as active treatments, such as delta-9-tetrahydrocannabinol (THC) or cannabidiol (CBD), while the prescription drugs are nabilone (Cesamet), dronabinol (Marinol, Syndros) and nabiximols (Sativex). These were administered as a pill, spray, oil or smoke or vapour. The researchers derived that participants who received active treatment and participants who received a placebo had the same levels of pain relief.

Furthermore, the placebo effect is considered extremely powerful in that it can even level to the effects of ibuprofen or morphine and other common pain-relieving drugs in the body, according to previous studies. In certain clinical trials about common pain medications, like aspirin and ibuprofen, placebos give similar pain relief as the actual drugs. That is not to say that the common pain medications are not effective; rather, the placebo can only rival with its mimicking effect capabilities. Both active medications and placebo only work through different neurobiological pathways. 

What do researchers and health experts say?

The lead author, Associate Professor and Research Group Leader in the pain neuroimaging lab of Karolinska Institutet in the Stockholm area, Karin Jensen, emphasised that the placebo response amounted to 67 percent of the pain relief linked to genuine cannabinoids. Important factors like the patients’ expectations of relief play a role in the analgesic effects related to cannabis-based treatments. 

It is like setting up the patients with what to expect and a certain kind of outcome. With this idea on their minds, the participants may expect the active drug and experience some sort of positive outcome. That is true with antidepressants; it’s true with pain medications; Harriet de Wit, an Experimental Psychologist and a Professor of Psychiatry and Behavioural Science at the University of Chicago who primarily studies the placebo effects, stated her insight about the new research. She also added that it is an interesting and very real phenomenon where it is certainly not ‘all in your head,’ and yet some of your brain circuits create the thoughts and expectations about the pill being taken.

Most pain-relieving medications are barely better than a placebo with the exception of opioids, Ted J Kaptchuk says, the director of the Program at Harvard-affiliated Beth Israel Deaconess Medical Center’s Placebo Studies and The Therapeutic Encounter [3]. 

Previous studies on cannabis as a pain reliever

The new study’s conclusion published by JAMA Network supported the claim of the International Association for the Study of Pain (IASP) which was conducted in 2021. Based on the 2021 findings by IASP, they do not recommend the use of marijuana for pain as there is not enough high-quality human clinical safety and efficacy evidence [4].

One similar study in 2020 found that using marijuana before entering the hospital for a surgical procedure can significantly worsen the pain during recovery. Additionally, patients who used weed before the surgical procedure tend to need more anaesthesia during the surgery. Plus, undergoing anaesthesia can put certain people at high risk, including older adults or people with chronic illnesses like diabetes. Cannabis users also needed more opioids during recovery [5]. 

How does a placebo affect the brain?

The placebo effect happens through various neurotransmitters being released in the brain, making particular parts of the brain activated. Among the neurotransmitters are endocannabinoids which are structurally the same as the active compounds found in cannabis. Explaining the placebo effect through the classic theory [6], it is when you believe the treatment you are receiving will make you feel better, and it technically becomes a self-fulfilling prophecy.

Discovered in the late 1700s, the placebo effects became the basis of numerous horrifying treatments physicians of the time used. In modern clinical trials, researchers in the field commonly administer the medication being tested to half of the study participants, while a sugar pill will be given to an equally matched group of people.

The role of news and social media in the placebo effect

Well, here’s a little more interesting part – the mixing of media in medicine. This new study also looked at the position of news and social media in amplifying the placebo effect in cannabis clinical trials. According to Jensen, their research team found positive media coverage after each of the cannabis clinical trials, even in studies that did not provide significant results. The researchers examined over 136 news items in media and blogs and categorised each story, whether positive, negative or neutral, in characterising marijuana as an effective pain-relief treatment. 

As media – whether traditional or new – may have a strong influence on information and public opinion, positive and extensive media attention can shape people’s placebo responses in subsequent clinical trials; however, the current study is not yet powered to address the possibility, and more research is needed to understand if this shaping of placebo responses actually formed. 

The bottom line

Having to treat chronic pain is known to be really challenging, as most clinical trials are not the same as in real life, following the statements given by the researchers and health experts. In fact, Kaptchuck further added that if, after checking with a doctor, you tend to find something that helps in relieving the pain while causing no significant harm, he would say go ahead and use it – it is that difficult to find the best pain reliever. However, it is still better to consult with your doctor before using anything, especially the use of medical marijuana. Essentially, the more effective a certain drug is at treating pain, the greater the likelihood of some side effects and other unwanted consequences, like dependency and addiction. 

[1] https://www.medicalnewstoday.com/articles/322051
[2]  https://pubmed.ncbi.nlm.nih.gov/36441553/ 
[3] https://www.health.harvard.edu/blog/does-cannabis-actually-relieve-pain-or-is-something-else-going-on-202212082863 
[4] https://www.iasp-pain.org/advocacy/iasp-statements/cannabinoid-non-technical-summary-2021/ 
[5] https://edition.cnn.com/2020/10/05/health/weed-pain-anesthesia-increase-wellness/index.html 
[6] https://www.bmj.com/content/370/bmj.m1668