Q: Can cannabis treat neuropathy? And if so, what products should I use for it?
A: While the initial answer may be a simple one, we don’t know yet. What follows is a review of what we do know.
According to the National Institute of Neurological Disorders and Stroke at the National Institutes of Health (NIH), over one-quarter of people over 65 suffer from neuropathic pain.
As I stated in a prior Ask Dr. Leigh column about cannabis and pain, pain is a complex neurological “protective” response involving the brain and spinal cord (the central nervous system) and nerves coming in and out of the spinal cord running throughout the body (the peripheral nervous system.) The endocannabinoid system plays a role in regulating pain sensation and modulating actions at all levels with cannabinoid receptors distributed all along these three levels of the ascending and descending pain pathways. There are both CB1 and/or CB2 receptors all along these areas and they are what our endocannabinoids interact with to create the physiological effects. It is proposed that both CB1 and CB2 agonists, molecules that bind and activate these receptors, are distributed in these regions of the brain and spinal cord and can affect pain transmission and perception and cause modulation to decrease pain. So, it would only make sense that the phytocannabinoids found in cannabis that react with these receptors should also affect and modulate pain transmission.
Neuropathic pain occurs after nerve injury. There are many causes, for example, chemotherapy can cause it, as well as traumatic injury to a nerve. Metabolic conditions such as diabetes can cause peripheral neuropathy. And central nervous system diseases like multiple sclerosis (MS) can cause central neuropathies. Neuropathic pain is often very hard to treat and it negatively impacts patients’ quality of life as well their ability to function day-to-day. And often the chronic nature can lead to anxiety and depression.
While there are many preclinical studies on pain and cannabinoids in animal models, they don’t always correlate directly to humans. Therefore, to practice evidence-based medicine we doctors need more human clinical trials, which in the US can be an issue due to cannabis’ federally illegal status.
There are numerous anecdotal reports and some international clinical trials dating back years that show smoked cannabis may be helpful alone or in conjunction with other treatments for many cases of neuropathic pain, with some added benefits reported such as improved sleep, function and mood. However, as a physician, I recommend vaping cannabis as a somewhat safer better alternative with less exposure to the toxic products of combustion produced by smoking.
Often many of these study results are a mixed bag, with some clinical trials warning it is not helpful in all neuropathy patients, but for those it does help, they seem to get mild to moderate pain relief which may be more pronounced in central, versus peripheral neuropathic pain.
Other studies looking at the worldwide reviews on cannabinoid medications for the treatment of neuropathic pain also report a range of results from not being effective to clinically meaningful benefits.
Therefore, unfortunately, like so much of the cannabis research today, often there are mixed reviews and recommendations for both patients and physicians alike with respect to its effectiveness. And even for cannabis-informed physicians like myself, I find it can be hard to sort through some of the research and recognize what if any, may also be veiled with political agendas.
Now, with respect to edible cannabis and neuropathic pain, there is even less direct clinical trials and research. However, if you have found that it works for your neuropathic pain, and as with many other chronic conditions, if your pain is something lasting all day, then inhaled formulations may not be the best option. The pharmacokinetics (which is the science of how our body metabolizes drugs) of inhaled cannabis shows it has a very quick onset of action but a shorter duration of action. Thus, it may be useful in breakthrough pain episodes as opposed to longer-lasting all-day pain. Therefore, a longer-acting cannabinoid formulation such as those found in edibles may be better for producing a more steady-state pain relief. And there is some research that indicates categorizing different types of usage may give us better data.
But in this evolving medical science journey with cannabis, we simply are not at the point to discuss what exact formulation of edible cannabis is best for any type of pain let alone neuropathic. However, we do know that both THC and CBD can suppress inflammatory and neuropathic pain, and, added to that, CBD may also have some added beneficial neuroprotective effects. So, finding a product or using a combination of both should be beneficial.
And clearly what physicians want and need, is more long-term unbiased human studies to cement its therapeutic benefits. But when it comes to neuropathic pain, less than 50% of patients achieve pain relief across a whole litany of different medications, the most potentially dangerous of which is opioid use. Therefore, working with your physician and using a trial and error approach for your neuropathic pain with cannabis by starting at a very low dose and slowly advancing the dose as needed, may be a prudent way to start.
Dr. Leigh Vinocur is a board-certified emergency physician who also has a cannabis consulting practice for patients and industry. She is a member of the Society of Cannabis Clinicians and a graduate of the inaugural class, with the first Master of Science in the country in Medical Cannabis Science and Therapeutics from the University of Maryland School of Pharmacy.
Originally published on greenstate.com, February 3, 2022.