Cannabis has been used as an analgesic (pain reliever) for thousands of years. Despite its rich medical history, it is only within the past 3 decades that the mechanisms by which cannabis delivers relief have become better understood. Cannabis contains approximately 100 molecular compounds known as cannabinoids that interface with the endocannabinoid system (ECS) upon consumption. These interactions produce recreational and medicinal effects.  While there remains a paucity of high-quality research on the relationship between marijuana and the ECS, the existing evidence supports the use of cannabis as a treatment for an array of conditions including pain.

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Cannabis Engages The ECS To Reduce Pain

The opioid and cannabinoid receptors are involved in pain-sensation, mood, appetite and memory. Agonists are potent analgesics: Endorphin (red) and tetrahidrocannabinol (green). iStock / selvanegra
The ECS is a neuro-modulatory system that pervades almost every major organ system. It is comprised of cannabinoid receptors, endocannabinoids, and the enzymes that synthesize and degrade endocannabinoids and phytocannabinoids. The ECS plays an important role in an array of bodily functions including the regulation of pain sensation.

The signaling that occurs through CB1 and CB2, the two main cannabinoid receptors in the ECS, assists in processing pain, including acute pain states. There is a dense concentration of CB1 receptors in the frontal-limbic brain circuits responsible for processing affective and emotional pain. CB2 receptors are prevalent in immune cells and play a role in processing inflammatory pain. THC, the most abundant cannabinoid in marijuana, has a strong binding affinity for CB1 and CB2. This means that it interacts with those receptors in ways that affect normal pain processing. While the evidence suggests that these interactions produce beneficial results for pain patients, THC’s psychoactive effects have complicated its medical efficacy.

Research Supporting Cannabis as Pain Therapy is Limited

Although the lack of well-controlled, randomized clinical trials weakens any certainty that cannabis can treat acute and/or chronic pain, current research suggests that cannabis does have clinical benefits for some pain patients. A 2016 systematic review of 15 randomized controlled studies found that cannabis was marginally better at reducing pain than a placebo. However, cannabis was more likely to cause adverse reactions than the placebo. These ambivalent findings led researchers to conclude that cannabis should be considered only after patients with pain symptoms did not find relief from 2 prior conventional therapies.

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The National Academies of Sciences, Engineering, and Medicine’s comprehensive 2017 literature review on the medical efficacy of cannabis determined that “there is substantial evidence that cannabis is an effective treatment for chronic pain in adults.” These findings were based on the evaluation of 5 systematic reviews. The report also noted that “very little is known about the efficacy, dose, routes of administration, or side effects of commonly used and commercially available cannabis products in the United States.”

Another systematic review of 43 randomized controlled trials published later in 2017 concluded, again, that cannabis may be effective for the treatment of chronic pain. The authors described the evidence supporting this theory as “limited” and specified neuropathic pain patients as those most likely to experience relief. The review also found that adverse events of the gastrointestinal systems were most likely to occur when cannabis was administered orally or oromucosally.

While the aforementioned reviews suggest that cannabis is an effective treatment for chronic pain, a 2017 systematic review of 11 systematic reviews of randomized controlled trials determined that cannabis’ actual efficacy does not live up to the public’s perception. The authors concluded that the evidence suggesting that THC/CBD spray as treatment of neuropathic pain is limited at best. They also stated that the evidence supporting cannabis-based medicines for the treatment of cancer pain, rheumatic pain, and gastrointestinal pain is inadequate.

At the end of 2017, a literature review of the current evidence of cannabis-based medicine in pre-clinical versus human trials found that cannabis produced mixed results when administered to humans. The review found that cannabis did little to reduce sensory pain, though it did reduce affective pain. Though preclinical trials studying the effect of cannabis on animals have provided robust support for cannabis as pain therapy, the authors concluded that “human evidence presently provides only reluctant support for broad clinical use of cannabinoid-based medications in pain therapy.”

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In early 2018, a review of 16 randomized, double-blind controlled trials of both plant-derived and synthetic cannabis medicines as treatment for chronic neuropathic pain in adults made this pragmatic conclusion: “the potential benefits of cannabis-based medicine […] in chronic neuropathic pain might be outweighed by their potential harms.” The authors disclosed that only 2 of the 16 trials in their review were of high quality, a finding that supports their overall claim that there is not enough good evidence to support cannabis as a treatment for chronic neuropathic pain.

Best Strains For Pain Relief

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While the research is ambivalent, the majority of these cannabis and pain studies conclude that marijuana has the potential to treat pain. In some cases, the studies determine that the potential positives outweigh the risks associated with cannabis consumption. The following strains have been identified as useful for chronic pain relief. These recommendations are based on anecdotal experiences and are not yet medically proven. More research is needed. Please consult your doctor.

  • OG Shark. This hybrid contains an average 25 percent THC with a negligible CBD content. OG Shark will provide a relaxing body high suitable for an evening in.
  • Pink Kush. An indica, Pink Kush is commonly used at night to reduce anxiety and encourage sleep. With an average 22 percent THC, the strain’s powerful body effects make it a frequent choice for patients seeking pain relief.
  • Skywalker. With an approximate 15 percent THC average, Skywalker is not quite as potent as strains with a higher concentration of THC. However, it is known for inducing an enjoyable relaxation that often leads to sleep.
  • Master Kush. The soothing body high produced by this indica makes it a staple for patients managing anxiety, insomnia, and chronic pain. Master Kush contains an average THC content of 20 percent and is recommended for nighttime use.
  • Black Tuna. This hybrid containing a THC average of 20 percent is known for its potent sedative effects. Black Tuna is recommended for nighttime use and has been used to medicate chronic pain and insomnia.