Cannabis and Chronic Pain

Chronic pain is defined as persistent pain that lasts for months to years. It is a debilitating condition that affects 20% of people worldwide. It can have a variety of causes, including tissue injury, inflammation, nerve damage or conditions such as migraine and fibromyalgia. The pain can range from mild to severe, and can greatly impact a person’s quality of life. Many chronic pain sufferers turn to nonsteroidal anti-inflammatory drugs (NSAIDs) and opioids to manage their symptoms, however, these medications come with a range of unwanted side effects. In this article, we will explore the risks and benefits of NSAIDs and opioids, and take a closer look at cannabis and its potential as a safer alternative for managing chronic pain.

NSAIDs 

NSAIDs are a class of medications that work by reducing inflammation and pain. Some of the most popular NSAIDs include ibuprofen, aspirin, diclofenac, naproxen, celecoxib, rofecoxib, etoricoxib, lumiracoxib and valdecoxib. While NSAIDs are generally considered safe, they can still cause a range of side effects, particularly with chronic use. Common side effects of NSAIDs include stomach ulcers, bleeding, hypertension, kidney failure, and an increased risk of cardiovascular events such as heart attack and stroke. People who are hypersensitive to NSAIDs can also develop allergic reactions such as hives, sinusitis, asthma and anaphylaxis, which can be life-threatening (Vonkeman 2010, Kowalski 2011).

Opioids

Opioids are a class of medications that work by binding to opioid receptors in the brain and blocking pain signals. Some of the most common opioid medications include codeine, oxycodone, hydrocodone and morphine. One of the most significant risks associated with opioids is their potential for addiction. Over time, the body can develop a tolerance to opioids, meaning that patients need increasingly higher doses to achieve the same level of pain relief. This can lead to dependence, and ultimately, addiction. Opioids also cause a range of other side effects such as sedation, dizziness, nausea, vomiting, constipation and respiratory depression (when the lungs fail to exchange carbon dioxide and oxygen efficiently). In some cases, opioids can even cause death due to overdose (Benyamin 2008). According to the World Health Organization, approximately 115 000 people died of opioid overdose in 2017. In light of the ongoing opioid epidemic, medicinal cannabis as a possible alternative for chronic pain management is becoming increasingly important. 

Cannabis

Cannabis has been used for centuries as a natural remedy for pain. It contains more than 100 different cannabinoids, which interact with the body’s endocannabinoid system to produce a range of therapeutic effects, including pain relief. Patient-reported data indicate that chronic pain management is one of the most common reasons for medical cannabis use (Reiman et al. 2017). While cannabis does not work for all types of pain, it is particularly effective for patients suffering from chronic neuropathic pain, nociplastic pain or pain related to chronic inflammation (Bhaksar 2021, Henson 2022). 

Neuropathic pain is caused by damage to the nerves, which trigger inaccurate pain messages to the brain. It is usually described as a stabbing, burning, shooting, or sharp pain. Common causes of neuropathic pain include cancer, diabetes, HIV, alcoholism, shingles, stroke and limb amputation. Nociplastic pain is defined as pain due to sensitization of the nervous system, without sufficient tissue damage to explain the severity of pain. Its causes are not fully understood, but it is thought to be a dysfunction of the central nervous system, where the processing of pain signals may have become distorted or sensitized. Conditions associated with nociplastic pain include migraine, fibromyalgia, irritable bowel syndrome, rheumatoid arthritis, osteoarthritis, low back pain, neck pain and multiple sclerosis, amongst many others. It has been theorized that dysfunction of the endocannabinoid system (ie. reduced endocannabinoid tone / clinical endocannabinoid deficiency) may contribute to the persistent pain in these conditions (Russo 2016, Fitzcharles 2021, Haviv 2022). 

Exogenous plant-based cannabinoids have been found to exert significant pain-relieving effects. In patients with chronic pain, medical cannabis treatment has been associated with improvements in pain-related outcomes, increased quality of life, improved function, and a reduced requirement for opioid analgesia (Abrams et al. 2011, Haroutounian et al. 2016, Cooper et al. 2018; Rod 2019; Sagy et al. 2019; Johal et al. 2020; Safakish et al. 2020; Okusanya et al. 2020). 

In a 2017 study investigating the use of cannabis as a substitute for opioids in 2897 medical cannabis patients, respondents overwhelmingly reported that cannabis provided relief on par with their other pain medications, but without the unwanted side effects. 97% percent of the patients “strongly agreed / agreed” that they were able to decrease the amount of opioids they consume when they also used cannabis, and 81% “strongly agreed / agreed” that taking cannabis by itself was more effective at treating their condition than taking cannabis with opioids. Similar results from a 2016 study showed that medical cannabis use was associated with a 64% reduction in opioid use, a decreased amount of medications and side effects, and a 45% improvement in quality of life. 

South Africa’s first observational clinical study on the replacement of opioids with medical cannabis for chronic pain management is currently underway.  Dr. Shiksha Gallow, Cannabis Clinician and principal investigator of this study, presented some preliminary results at the Cape Town Cannabis Expo on the 25th of March 2023. Thus far, they have collected data from 54 patients with varied pain diagnoses including migraine, rheumatoid arthritis, multiple sclerosis and cancer related pain. A total of 45 patients (more than 80% of patients thus far) were weaned off their opioid medication completely within a period of three months, using doses of 0.25 – 1g vaporized cannabis flower per day. 

One of the biggest advantages of cannabis is that it is generally considered to be much safer than opioids and NSAIDs. Unlike opioids, cannabis does not cause respiratory depression. In fact, the opposite is true, as cannabis has been shown to cause dilation of the airways, which can last anywhere between 1 – 6 hours, depending on the route of administration (Tashkin 1973). Additionally, cannabis has a lower risk of addiction and overdose compared to opioids, making it a potentially safer option for patients who require long-term pain management. Another advantage of cannabis is that it can be used in a variety of forms, which means that patients have more options for managing their symptoms, and can choose a method that works best for their individual needs. 
While more research is needed to fully understand the potential benefits and risks of cannabis for chronic pain, early studies suggest that cannabis based medicines have a good tolerability and safety profile relative to opioids and NSAIDs and have negligible dependence and abuse potential (Henson 2022). It is important to note that everyone is different and that medical cannabis treatment, like most other therapies, should be individualized to minimize potential side effects and drug-drug interactions. If you are considering using cannabis for chronic pain management and want more information on cannabis dosing and administration, please refer to our previous blog post on “Finding your optimal dose”.