Since ancient times its been known that cannabis can provide relief from a variety of different types of pain. Recent estimates show that chronic pain affects up to 7.8 million people in the United Kingdom alone and the current pharmaceutical strategies for mitigating chronic pain have led to the addiction to nearly one million of those people. Over the counter non-steroidal anti-inflammatory drugs (NSAIDs) are not much better and can have a variety of adverse effects such as liver damage, erectile dysfunction, and potential for overdose. The search for safer alternatives prompted research into cannabis’ effects as an analgesic and scientists are now beginning to unravel how the compounds in cannabis interact with the body to produce these effects in a less harmful and less addicting fashion than over the counter medications and prescribed pharmaceuticals.
The endocannabinoid system primarily consists of two types of receptors called CB1 and CB2, with CB1 being predominant in the central nervous system and CB2 being prevalent in the periphery. Each of these receptors plays a different role in modulating the sensation of pain at various levels of pain processing pathways. Interestingly, some pain medications rely on the same pathways cannabis does to produce pain relief. Acetaminophen, a common ingredient in readily available pain medications is metabolized by the body into the cannabinoid compound AM-404. The action of this compound at the cannabinoid receptor CB1 is partially responsible for acetaminophen’s anti-inflammatory and pain relieving properties[ref]Ottani A, Leone S, Sandrini M, Ferrari A, Bertolini A. The analgesic activity of paracetamol is prevented by the blockade of cannabinoid CB1 receptors. Eur J Pharmacol. 2006;531(1-3):280-1.[/ref].
Some types of pain manifest themselves in the form of inflammation. The CB2 receptor is a key modulator of inflammation and the processing of the pain it can cause. Compounds in cannabis such as THC, CBD, beta caryophyllene, alpha pinene, and beta myrcene bind to cannabinoid receptors and other targets to produce analgesic and anti-inflammatory effects[ref]Gertsch J, Leonti M, Raduner S, et al. Beta-caryophyllene is a dietary cannabinoid. Proc Natl Acad Sci USA. 2008;105(26):9099-104.[/ref].
Cannabinoid compounds, particularly the acidic versions found in the raw plant (THCA and CBDA), also exert their anti-inflammatory effects by inhibiting the enzymes that produce pro-inflammatory molecules called prostaglandins[ref]Ruhaak LR, Felth J, Karlsson PC, Rafter JJ, Verpoorte R, Bohlin L. Evaluation of the cyclooxygenase inhibiting effects of six major cannabinoids isolated from Cannabis sativa. Biol Pharm Bull. 2011;34(5):774-8.[/ref]. It has been reported that the anti-inflammatory capacity of THC, the primary psychoactive component in cannabis is up to twenty fold to that of aspirin and up to twice that of hydrocortisone[ref]Takeda S, Misawa K, Yamamoto I, Watanabe K. Cannabidiolic acid as a selective cyclooxygenase-2 inhibitory component in cannabis. Drug Metab Dispos. 2008;36(9):1917-21.[/ref].
Numerous clinical trials performed by the Center for Medical Cannabis Research in San Diego also confirm the efficacy of cannabis as a therapeutic tool and is effective in providing relief from chronic neuropathic pain due to diabetes and HIV[ref]Wallace MS, Marcotte TD, Umlauf A, Gouaux B, Atkinson JH. Efficacy of Inhaled Cannabis on Painful Diabetic Neuropathy. J Pain. 2015;[/ref]. The diabetes study also showed reductions in pain in a dose dependent fashion while the HIV study showed that smoked cannabis led to significant reductions in pain in comparison to pre-treatment baseline levels.
These are just a few of some of the studies performed that support the use of cannabis for pain relief. There is an overwhelming amount of data acknowledges cannabis as an effective medicine, however until the stigmas surrounding this plant change it will continue to be viewed as inferior.