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Can Cannabis Help With Chronic Pain?
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11 min
Gleb Oleinik by Gleb Oleinik

Overview

Cannabis has been used to relieve pain for thousands of years. Today, it remains a popular option for chronic pain caused by such difficult-to-treat conditions as fibromyalgia, cancer, and multiple sclerosis. 

Chronic pain is the most common reason people turn to medical cannabis. In fact, according to a 2019 study, two thirds (67.6%) of all American medical cannabis patients in 2016 had chronic pain as their qualifying condition.

Research indicates that the pain-relieving properties of cannabis are mediated by our body’s endocannabinoid system. 

The Endocannabinoid System

The endocannabinoid system consists of cannabinoid receptors, endocannabinoids, and the enzymes that build and break down the endocannabinoids. 

Discovered in the 1990s, this system plays a critical role in maintaining homeostasis — a state of balance. It regulates many key functions of the body, including mood, metabolism, learning and memory, sleep, immunity, and pain.

The endocannabinoid system has two receptors: CB1 and CB2. CB1 is predominantly found in the central nervous system, while CB2 is abundant in immune cells. These receptors are activated by two main endocannabinoids produced within the human body: anandamide and 2-AG. 

Phytocannabinoids from the cannabis plant, such as THC and CBD, also interact with the endocannabinoid system and function similarly to endocannabinoids.

The endocannabinoid system plays an important role in controlling pain. This includes both major types of pain: nociceptive (caused by actual harm to the body, such as a burn) and neuropathic (caused by damage to nerves that relay pain signals). 

At the most basic level, studies show that both the CB1 and CB2 receptors are involved in almost every aspect of the pain pathway: the chain of events leading to our perception of pain.

More specifically, the CB1 receptor is found in many parts of the peripheral and central nervous systems involved in pain. For example, this receptor is present in:

  • Nociceptive nerves that sense pain caused by potentially damaging stimuli
  • The spinal cord, helping reduce or enhance pain signals traveling to the brain
  • Parts of the brain associated with nociception, such as the cortex and amygdala
  • Frontal–limbic brain circuits that play a role in how we process pain psychologically and emotionally

The importance of this receptor in regulating and, importantly, reducing pain was highlighted in a 2007 study where researchers deleted the CB1 receptors from neurons that sense pain in mice (aka “CB1 knockout”). This deletion greatly reduced the analgesia (pain relief) provided by cannabinoids in mouse models of inflammatory and neuropathic pain.

Meanwhile, the CB2 receptor seems to play a bigger role in inflammatory pain. This makes sense because inflammation is a process controlled by immune cells, which is where the CB2 receptor is mostly found. 

This was demonstrated by a 1999 study where mice with inflammation of the extremities were given a compound that activated the CB2 receptor, reducing inflammation and the associated pain. Also, some studies show that the CB2 receptor is found in other parts of the body, such as sensory neurons involved in neuropathic pain.

In addition, anandamide and 2-AG are known to produce pain-relieving effects, and research demonstrates that chronic pain is associated with increased levels of both cannabinoid receptors and endocannabinoids themselves. This suggests that the body is attempting to deal with pain by upregulating the endocannabinoid system. 

To summarize, it’s clear that the endocannabinoid system plays a central role in regulating pain. Researchers believe that “cannabis-based medications which enhance endocannabinoid function may represent a novel therapeutic solution to disorders associated with chronic pain.”

Cannabis & Chronic Pain

Chronic pain places an enormous burden on individuals and given how common it is, on society as a whole.  While cannabis has been used for therapeutic benefits on a very wide variety of medical conditions, pain is one of the most studied and common ailments in which cannabis is used.  As a result, while research on cannabis has been severely limited due to legal reasons, there are more studies about pain than other conditions. We’ve included some of the most significant, high-quality studies below, which include chronic pain related to cancer, neuropathy, multiple sclerosis, arthritis, fibromyalgia, and migraines.

One highly-cited 2008 study examined the effects of smoking cannabis on neuropathic pain. A total of 38 patients smoked either high-THC, low-THC, or placebo cannabis (dummy medicine). Unlike placebo, both cannabis options resulted in significant pain relief.

In addition, a 2012 study looked at whether cannabis can help with spasticity, a common, painful symptom of multiple sclerosis. Thirty-eight participants smoked cannabis (4% THC) vs. placebo. Only the cannabis group experienced significant improvement in pain.  

Meanwhile, a 2006 study by British researchers examined the effects of Sativex, a cannabis-based drug, on pain associated with rheumatoid arthritis. A total of 58 patients were given the drug or placebo. Only the Sativex group experienced a significant improvement in pain. 

Furthermore, a 2010 study analyzed the effectiveness of a cannabis extract containing only THC or THC plus CBD in patients with advanced cancer pain that wasn’t responding to regular opioid medications. A total of 177 patients were given THC extract, mixed CBD/THC extract, or placebo. Only the CBD plus THC extract resulted in a significant reduction of pain, with 43% of the patients taking it reporting a 30% or greater improvement. This is an especially notable finding because it highlights the effectiveness of drugs that contain multiple cannabinoids over those that only have THC or CBD.

There’s also evidence that cannabis works for fibromyalgia pain. In one highly-cited 2008 study, patients were given Nabilone, a THC-based drug, or placebo. Only the THC group experienced significant improvement in pain (average of 6.86 down to 4.82 on the visual analog scale) and quality of life.

Another 2016 study looked at the benefits of medical cannabis in 274 people with various kinds of treatment-resistant chronic pain. Cannabis not only reduced pain but also significantly reduced the use of prescription opioid medications.  This is an important studying highlighting a potential alternative to opiates, whose overuse has led to an epidemic in many countries, including the USA and Europe.  

Additionally, a  2016 study looked at the use of medically prescribed cannabis in 121 people with migraine headaches: another type of chronic pain. In total, 85.1% of the patients reported having fewer migraines per month (average of 10.4 down to 4.6). 

While these individual studies point to the chronic pain-relieving benefits of cannabis, reviews of multiple studies are even more powerful because they combine all of the best evidence to get a clear picture of the overall research consensus on a topic.

One such systematic review looked at the results of 28 clinical studies on the use of cannabinoids for chronic pain, including cancer pain, neuropathic pain, fibromyalgia, multiple sclerosis, and rheumatoid arthritis. This study concluded that “There was moderate-quality evidence to support the use of cannabinoids for the treatment of chronic pain.”

Side Effects

While cannabis represents an incredibly effective option for chronic pain, especially in cases that don’t respond to conventional medicine, it’s not without its downsides.

Most notably, cannabis is widely known to cause psychoactive side effects such as impaired memory, anxiety, and euphoria. It can also cause psychosis in some individuals.  However, it’s important to highlight that these effects are associated with THC, whereas CBD-rich preparations, such as CBD oil, are not intoxicating

In addition, cannabis-based preparations can cause other side effects drowsiness, fatigue, dry mouth, and changes in appetite. All in all, however, these effects are minor and cannabis is a remarkably safe substance, especially when compared to pharmaceutical drugs. 

For example, opioids, the most common prescription for chronic pain, are known for their addictive potential and associated withdrawal effects.

When considering the use of cannabis for chronic pain, or any other medical condition, it is important to consult with your doctor before initiating therapy.  

Legal Use

Convincing research along with real world evidence of the benefits of cannabis in those suffering from chronic pain has resulted in most countries with medical cannabis programs allowing for the use of cannabis for chronic pain. This includes countries such as Canada, Germany, and the Netherlands. 

However, there are some exceptions. For example, the UK has an extremely limited medical cannabis program that currently only allows for the use of medical cannabis preparations such as Sativex for MS-related spasticity.

Meanwhile, in the United States, patients can turn to medical cannabis for chronic pain relief in the District of Columbia and a total of 33 states: Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Hawaii, Illinois, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, Washington, West Virginia, Utah, and Vermont.

Conclusion

Cannabis has been used to treat chronic pain for millennia. Now, thanks to medical research, we know that cannabis achieves its pain-relieving effects through the endocannabinoid system.

More importantly, we have clinical evidence that medical cannabis preparations work for all sorts of chronic pain, including cancer, neuropathy, fibromyalgia, multiple sclerosis, arthritis, and migraine pain.

This is significant not only because many of these conditions don’t respond to standard treatment but also because cannabis has less serious side effects than many prescription pain medications. As such, the question is not whether cannabis helps with chronic pain but how we can make it even more effective.

About Chronic Pain

Overview

It is estimated that chronic pain affects as many as 100 million people across Europe. In the UK, an estimated 28 million people in the UK alone suffer from chronic pain, and among those aged over 75, that jumps as high as 62%. 

While acute pain comes and goes over the course of seconds, minutes, hours, or days, chronic pain is a condition that remains over a long period of time. As a result, it can have a tremendous impact on quality of life and impact practically every aspect of life. 

It’s often connected to long-term disorders such as arthritis and fibromyalgia, but it can also develop after an injury or medical condition—even those that have been treated. Chronic pain can come on suddenly, or develop gradually over time. It can be present practically anywhere in the body. 

It’s important to note that chronic pain and chronic pain syndrome (CPS) are real and cause real distress. While others may not be able to actually “see” the pain, it can be ever present, and shouldn’t be dismissed as something that is “all in your head.”

Symptoms

The main symptom of chronic pain is ongoing pain or discomfort that lasts for three to six months or longer. When the cause of the pain is unclear in origin, it is known as chronic pain syndrome (CPS). 

Chronic pain syndrome can be accompanied by secondary symptoms as well as the unexplained pain. These usually include but are not limited to:

  • Anxiety and depression, due to fear of pain or the consequences of pain
  • Insomnia, because the pain keeps you from sleeping well
  • Stress and irritability 
  • Feelings of guilt about unexplained pain preventing you from living your ideal life
  • Loss of interest in sex

When to see a doctor

If you’ve been in pain for 12 weeks or more, the pain isn’t getting any less, and there’s no apparent reason for the pain, you should consult with your doctor. In addition to exploring the cause of the pain and seeking out a solution, they can also help provide much needed pain relief and resources for coping with chronic pain.

Diagnosis

A doctor will conduct a formal evaluation for your pain which will often start with a history and a comprehensive physical exam, pinpointing where the pain is and what may be causing it. In addition, he/she may order blood tests and imaging for further evaluation. Often, a specific cause for the pain will be found. Sometimes that isn’t the case, as in common conditions such as chronic pain syndrome, fibromyalgia, IBS, and other potentially disabling pain conditions.

Causes

Researchers are still uncertain about what causes chronic pain. It’s possible that it’s a “learned response.” This means that your pain was originally caused by a certain medical or physical issue, but your brain continued to send the same pain signals even after the cause of the pain was removed. It’s also thought that people with chronic pain syndrome might have a different set of reactions to stress that makes them feel pain. 

There are also certain conditions or incidents that seem to provoke chronic pain. These include:

  • Strained or sprained muscles and broken bones that continue to cause pain even once they have healed
  • Back pain and headaches
  • Arthritis
  • Fibromyalgia
  • Infectious etiologies such as herpes infections and Lyme disease
  • Cancer 
  • Nerve damage
  • Inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS)
  • Acid reflux and stomach ulcers
  • Endometriosis

Women are more likely to get chronic pain syndrome than men, and it is more commonly found in sufferers of mood disorders such as anxiety and depression. Those suffering from chronic pain may also suffer from sleep problems, and chronic pain, unfortunately, correlates with onset of other chronic conditions such as diabetes, hypertension, heart disease, and cerebrovascular disease. 

Treatment

Given the disabling symptoms chronic pain causes and its impact on quality of life along with its correlation with other troubling conditions, treatment of chronic pain is of paramount importance. 

Chronic pain is very difficult to cure entirely, but it can be managed and treated. There is no perfect treatment. Different techniques and treatments are effective for different people and often an integrative approach, combining several therapies, works best. Treatment should be personalized for the specific type of pain and sufferer. Many people have to try many different therapies before finding adequate pain relief, and often treatments have side effects which can be intolerable or harmful. Therefore, the goal is not necessarily pain relief but improving quality of life. 

Medication 

Most people with chronic pain begin by taking pain medication, but that is not always the ideal solution. There’s a risk that you’ll become dependent on and/or addicted to your pain medication, and that you’ll be led towards stronger, more addictive painkillers. Furthermore, it often does not tackle the actual cause of the pain, which is critical with chronic pain. 

Sometimes, antidepressants, antiseizure drugs, and muscle relaxants can help control chronic pain better than painkillers. 

  • Antidepressants can increase certain neurotransmitters such as serotonin, dopamine, and norepinephrine, which help regulate pain, thereby potentially decreasing pain and improving mood. There are multiple types of antidepressants including SSRIs (selective serotonin reuptake inhibitors), SNRIs (serotonin norepinephrine reuptake inhibitors), and tricyclic antidepressants with the tricyclics and SNRIs used more for pain. Side effects can include insomnia, weight gain, and nausea. 
  • Antiseizure drugs used for conditions including epilepsy and bipolar disorder are often used in chronic pain. By blocking transmission between nerve cells, they can often be an effective way to reduce pain. The side effects of anti-epileptic drugs can include fatigue and drowsiness, increased clumsiness, and nausea. They can also affect your emotions and make you more irritable.
  • Anti-anxiety drugs. While not directly reducing pain, anti-anxiety drugs can make dealing with pain more manageable by improving relaxation and sleep. The side effects can include insomnia, restlessness, nausea, and headaches.
  • Muscle relaxants help relieve tight muscles that have gone into spasm and are causing muscle pain, but they can also cause confusion, dizziness, headaches, and depression.

Exercise 

Although chronic pain can make ambulating and moving in general a nightmare and cause more pain, exercise is actually the best thing you can do to combat chronic pain. Exercise releases endorphins, which are the body’s natural pain relievers and help lift your mood, whereas staying in bed just makes your body weaker and leads to more pain. Exercise also reduces stress, which tends to play a big part in chronic pain. Besides that, it also improves sleep, and increases the same neurotransmitters that antidepressants do. 

Yoga can be particularly useful, since it combines stretching that improves your body’s strength with mind-body balance, which can also be effective at combating chronic pain. 

Physical therapy and massage can also help to ease the pain from tight muscles that have gone into spasm. Strength training builds muscle strength, helping your muscles to stretch and relax and eases pain from arthritis and back pain. 

Alternative therapies

There are a number of alternative therapies that help reduce chronic pain. These include:

  • TENS therapy. A TENS machine sends a low electric current through your body to disrupt pain signals. They are inexpensive to buy online or in stores.
  • Acupuncture can help to increase your pain threshold, helping you to cope with the pain, relax your muscles, and encourage your body to release natural painkillers. 
  • Deep breathing exercises that train your muscles to relax, releasing endorphins in your brain and soothing tight muscle pain. 
  • Meditation helps many people to relax and let go of stress, which is important because stress makes your muscles more tense, adding to muscle and joint pain, and increases pain in general. 
  • Biofeedback is a way of learning how to control your involuntary physical processes, like heart rate and your pain responses. You’ll be attached to a computer with body sensors, which guides you to relax your muscles, let go of tension, and reduce your pain.
  • Mindfulness. Multiple studies have shown that practicing mindfulness can reduce chronic pain scores and improve mood and sleep. 

Diet

Many people find that certain foods make their pain worse, while other vitamins, supplements, and foods can ease their symptoms. Red wine and cheese are common culprits for migraines and severe headaches. You might need to keep a food diary to see if there’s any connection between your symptoms and what you eat. 

Supplements and natural remedies

Although there’s no scientific proof, many people find that some herbal and natural remedies help relieve chronic pain. Some of the most popular products include:

  • Omega-3 and omega-6 fish oil supplements can be particularly helpful against joint pain like arthritis.
  • Glucosamine has been found to relieve joint and muscle pain in many people with chronic pain.
  • Chondroitin sulfate occurs naturally in the cartilage and tissues around your joints. It’s often effective for chronic pain from aching muscles and joints, and pain from osteoarthritis.

Complications

The burden of chronic pain on individuals and society as a whole is huge. Partly as a result of doctors prescribing opioid pain treatments for chronic pain, an opioid epidemic has killed tens of thousands of people in the US. Opioid painkillers can also lead to other forms of substance abuse. 

As a result of chronic pain, people are not the husbands/wives, mothers/daughters, fathers/sons workers and friends they’d like to be. Mood and sleep are affected, and down the line, a host of other dangerous chronic conditions can follow. 

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