“Doc, my legs are killing me,” says my patient, a veteran in his late 60s whose legs were mangled by a mortar blast in Vietnam. We have been trying to taper his morphine, which no longer works and has caused fatigue and erectile dysfunction. The taper is slow, each notch down resulting in anxiety and withdrawal.
“I was wondering how you felt about marijuana for my pain?” he asks.
Here’s the problem: we don’t have a full understanding of whether medical marijuana really works to treat chronic non-cancer pain. In fact, it may have very real personal and public health risks.
With the legalization of medical marijuana in Connecticut in 2012, and possible state legislation around recreational marijuana, it is important to clarify the balance between benefit and harm. Some may argue that medical marijuana has an important role in the treatment of pain because it is a safer alternative to opioids, but it’s not that straightforward. A recent report from the National Academies of Science found that states with more permissive medical marijuana laws also have higher rates of fatal drug overdoses.
As a primary care physician who treats many chronic pain patients, I find giving clear advice on medical marijuana difficult to do.
What do we know about medical marijuana when it comes to treating chronic pain?
Right now, there is no unequivocal proof that medical marijuana helps treat chronic non-cancer pain. A review on this topic published in the Annals of Internal Medicine found “low-strength” evidence that some cannabis preparations may alleviate nerve pain, but not enough solid conclusive information on other types of pain. For patients like mine, who suffer from pain from nerve damage, there might be a benefit, but better studies are needed to prove it. Many patients with chronic pain don’t have nerve pain; they have pain from worn-out joints, or from irritated muscles, tendons or ligaments. For those patients, there is just not enough available information.
We do know that there are very real potential harms.
Marijuana is clearly associated with psychotic symptoms. This may mean paranoia, or a more serious derailing of thoughts and loss of connection to reality. Psychotic symptoms do not occur in everyone and we need better research to define who may be at risk.
Cannabis exposure before the age of 25 affects brain development and can cause long-term (possibly permanent) changes to brain structure and function.
Marijuana can cause confusion in active users, and it’s unknown whether these can lead to long-term problems with memory. Medical marijuana can increase risk for developing an addiction, having a car accident, falling, certain infections and even recurrent vomiting. We have a poor understanding of how cannabis use affects opioid use, or the risk for opioid-related side effects, including overdose.
While we wait for larger, better studies to guide us, doctors are being asked to give medical advice with a blindfold on.
There is no shortage of people who swear by the therapeutic power of cannabis. In the midst of the opioid epidemic, we are desperate to find alternatives to help manage chronic pain. But we simply do not know enough about cannabis to make the call.
Since California first legalized medical cannabis in 1996, 33 states have followed suit. Legalization permits use in qualifying patients with terminal or debilitating medical conditions, who, based on judgement by a health care professional, may benefit. This protects individuals who use it from criminal or civil consequences. These compassionate use arguments, though compelling from a legal perspective, do not hold up to the necessary rigorous standards the health care profession should place on therapeutic interventions (large, unbiased studies over long periods of time that establish the correct dosing and distinctly weigh the pros and cons).
There are many valid arguments in favor of legalization: decriminalizing marijuana unburdens an already saturated prison system, results in a more regulated, safer supply and allows states to generate tax revenue. All these arguments are worthy social debates, but none of them should masquerade under the guise of “medical” benefit, or be good reason for doctors to play gatekeeper for a potentially hazardous substance. It confounds me why something yet to be adequately researched for chronic pain, can be labeled as “medical.”
For me, I see increasing use, an absence of solid proof of medical benefit in chronic pain conditions and a lot of potential downsides. My answer to my patient: We don’t know. Why don’t we try other things and revisit this question down the road?
Dr. Juliette Spelman is an assistant professor at the Yale School of Medicine, Department of Internal Medicine. She also works as an internist in primary care at the West Haven Veterans Affairs hospital, and has a particular interest in the care of veterans returning from recent conflicts.