Modern medicine is great at treating acute pain — the type that results from some sort of injury and lasts around three to six months. Some of the causes of acute pain are soft tissue injuries, surgeries, broken bones, and childbirth. Acute pain is generally managed with non-steroidal anti-inflammatory medications (NSAIDs) or opioids. Once the injury has healed, medication can be discontinued and life can return to normal (1).
While doctors have made great progress at treating acute pain, we struggle with treating chronic pain – pain that is ongoing, usually lasting longer than six months. Chronic pain may be linked to an ongoing illness, such as inflammation (for example, arthritis), cancer or neuropathy, but that is not always the case. Some people have chronic pain without a predisposing illness, or after the underlying injury or illness causing the pain has healed. Pain signals in the nervous system can remain active months or even years after the underlying illness or injury is gone. With chronic pain, your nervous system is sometimes altered, making it more sensitive to pain. As a result, painful sensations might feel even more severe and last longer.
As early as 2900 BC, the Chinese recorded the use of cannabis for pain and muscle spasms (2). Now, thousands of years later, we are still trying to determine if these, and other medical conditions, can effectively be treated by cannabis. While the available research is limited, existing studies provide substantial evidence that cannabis is an effective treatment for chronic pain. However, little is known about the efficacy of medical cannabis in alleviating chronic pain, what dosage is appropriate, how the drug should best be administered, or what possible side effects might occur with commonly used and available cannabis products in the U.S. Given the burgeoning availability of cannabis products in much of the country, more research is needed on the various forms, routes of administration, and combinations of cannabinoids (3).
There is a reason why so little research is conducted on the medical uses of cannabis. In 1976, the United States Controlled Substances Act classified cannabis as a Schedule I drug, meaning that it has a high potential for abuse and no acceptable medical uses. Individual states have legalized its medicinal use, however, cannabis remains federally classified as a Schedule I drug, making it difficult to study in the US. Thus, much of the research into medical cannabis comes from outside of the US.
In the meantime, we do know this:
1. The body makes its own cannabinoids that are similar to the active ingredients in cannabis. They are produced in injured tissues and suppress sensitization and inflammation (1, 2). Therefore, there is evidence of a natural role for the cannabinoids in pain modulation (3).
2. There is also evidence of a natural role of cannabinoids in the control of movement, and memory (3).
3. The natural role of cannabinoids in immune systems is complex, multi-faceted, and remains unclear (3).
4. The brain develops tolerance to cannabinoids (3).
We are just beginning to understand the complexity of cannabinoids and their interactions with the human body. As with all medications, it is likely side effects as well as benefits will come to light as the use of medical cannabis increases. Patients and their physicians need to carefully consider the risks and benefits of cannabis use carefully when they are considering this new treatment modality.
1. Vuckovic, S, Srebro, D, Vujovic, KS, Vucetic, C, and Prostan, M. Cannabinoids and Pain: New Insights from Old Molecules. Frontiers in Pharmacology 9; 1-19. 2018.
2. Hill, KP, Palastro, MD, Johnson, B and Ditre, JW. Cannabis and Pain: A Clinical Review. Cannabis and Cannabinoid Research 2.1; 96-104. 2017
3. National Academies of Sciences, Engineering, and Medicine. The health effects of cannabis and cannabinoids: the current state of evidence and recommendations for research. Washington, DC: The National Academies Press, 2017