Study Summary: Cannabis and Pain

Updated: Oct 9

A February 2022 research study conducted in Brazil that was entitled "Cannabis and Pain: A Scoping Review" and published in the Brazilian Journal of Anesthesiology explored the potential efficacy of the cannabis plant for the treatment of pain.

The detailed research examined the evidence regarding how the cannabinoids produced by hemp and cannabis may be of value in the treatment of a number of pain types and via a variety of biochemical mechanisms and pathways.


"The detailed research examined the evidence regarding how the cannabinoids produced by hemp and cannabis may be of value in the treatment of a number of pain types."

Types of Pain

The study reported that pain is "a subjective experience that is composed by sensory, physiological, motivational, cognitive, and affective factors." It noted that the "three main pain systems" are nociceptive, neuropathic, and central.


The three main pain systems are central, neuropathic, and nociceptive, as defined in brief below:

  • Centralized pain: Results as amplification of peripheral system due to persistent central nervous dysfunction.

  • Neuropathic pain: Neuropathic pain is caused by damage to the nerves. This damage triggers inaccurate pain messages to the thalamus and the cortex in the brain.

  • Nociceptive pain: Due to tissue damage and usually described as throbbing, aching, or sharp. This type of pain has the important task of "warning the individual about danger."

Pain is a Complex Process

The study's authors explained that pain "is a complex process modulated by many subjective factors" and that this makes the creation of simple pharmaceutical targets difficult.


The study reported that, among medical professionals, "cannabis is rarely the first [treatment] for pain" and that patients typically begin pain treatment "with nonsteroidal anti-inflammatory drugs (NSAIDs), cyclooxygenase inhibitors (COX), and opioids."


Brief History of Medical Cannabis

The study reported that cannabis has been used for centuries for many purposes, including medicinal. "The Shennong Ben Cao Jing encyclopedia, which dates back to 2900 BC in China, recommended the seeds as treatment for pain, constipation, and malaria," reported the researchers. It noted that the herb "was used along with wine to create an anesthetic effect for patients undergoing surgery" in China during the period.


"Cannabis has been used throughout history by different civilizations—mostly bypassing formal usual approval processes."

"Around 1000 AC, cannabis flowers became popular in India, providing analgesia, hypnotic, antispasmodic, and anti-inflammatory effects," noted the scientists. They stated that cannabis was listed in the 3rd edition of the U.S. Pharmacopoeia in 1851 as a treatment for "gout, rheumatism, tetanus, cholera, hysteria, depression, delirium tremens, and uterine bleedings."


The herb remained in this pivotal medical reference for nearly a century, until 1941, after the Marihuana Tax Act of August 1937 made hemp and cannabis illegal in the United States.

"In the 21st century, cannabis began to be explored by Western medicine," reported the study. It noted that "only plant extracts [have been] used" and that active ingredients have been isolated "both from leaves and flowers."

The Study

The design of this study was that of a literature review that analyzed previous studies on the topic. "On April 2nd, 2020, a search in PubMed was performed" for keywords such as "pain," "acute pain," "pain management," "chronic pain," "fibromyalgia," and many others


The initial search yielded 9,610 references, of which 5,742 articles were considered irrelevant and were excluded," reported the study. This included "articles reviewing the use of marijuana or cannabis-based drugs for the treatment of any symptom different from pain." The scientists narrowed the articles reviewed to 111.


"The study analyzed prior research for the potential efficacy of cannabis for pain in a variety of areas, including acute pain, chronic pain...."

Results

The study analyzed prior research for the potential efficacy of cannabis for pain in a variety of areas, including acute pain, chronic pain, multiple sclerosis-related pain, pain resulting from rheumatic diseases, cancer pain, headache, and how cannabis use for pain might decrease use of opioids.

"There is evidence, though limited, that support the efficacy of cannabis-based medicine," conclude the study. However, the study's authors noted that "this evidence is insufficient to provide any recommendations of cannabinoids in clinical practice."


Regarding the safety profile of cannabis for medical conditions, it was found to be "mostly safe, having common mild adverse effects such as dizziness and euphoria." Despite its acceptable safety profile, the researchers noted that "there is an important need for research" on the safety of medicinal cannabis use, particularly its safety, "especially on vulnerable population such as elderly patients."


Cannabis was found to be "mostly safe, having common mild adverse effects such as dizziness and euphoria."

More Research Needed

Cannabis in the treatment of pain "is a topic where much research is needed to evaluate benefits and risks patients," concluded the research. It emphasized that important elements such as route of administration (consumption avenue) and dosage "have not been clearly established."


"As cannabis use increases in several countries, answers to these questions might be coming soon," summarized the study.


View the original study.


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