Cannabis and Chronic Pain: What You Need to Know Before Using Medical Marijuana

Health Writer

As of January 2018, 29 states, plus Washington, D.C., Guam, and Puerto Rico have comprehensive legal medical marijuana programs. And eight states, plus D.C., have legalized the recreational use of marijuana. But it’s important to remember that marijuana is still classified as a Schedule 1 substance under the Controlled Substances Act, and thus it is still a federal offense to possess, distribute, or sell marijuana.

If you’re in a legal state and have or can obtain a medical card, or want to buy recreationally to use medically, you may have more questions than answers. While dispensaries are allowed to sell marijuana, they often aren’t equipped to answer questions about how best to use it medically. And while your physician may have written you a prescription, she might not have had any additional information about medical use of marijuana.

While there are many conditions for which medical cannabis can be used, this article focuses on one: chronic pain. There are two very important questions when considering using cannabis for chronic pain: Is it safe? And is it effective? But first, you might need to ask: What is medical cannabis, exactly?

What is medical cannabis?

Cannabis, or the marijuana plant, contains over 400 different chemical constituents, with over 100 cannabinoids, i.e., chemicals found only in the cannabis plant.

Tetrahydrocannabinol (THC) is the most abundant cannabinoid in the plant, but CBD, or cannabidiol, is the second most abundant cannabinoid, and new research suggests it has anti-inflammatory, anti-anxiety, and analgesic (pain-relieving) effects. THC is responsible for the “high” feeling cannabis users get, while CBD blunts that effect. Some high-THC marijuana is over 20 percent THC, while average CBD levels are generally under four percent. But more and more, medical cannabis with higher levels of CBD, such as 1:1 CBD:THC or 2:1 CBD:THC, are being used with success, particularly for neuropathic pain, PTSD, multiple sclerosis, Crohn’s disease, and treatment-resistant epilepsy.

Cannabis can be consumed in a variety of methods:

  • Vaporizing (much safer than smoking)
  • Smoking
  • Edibles like tinctures (liquid extracts typically dissolved in alcohol) or butters, oils, capsules, and baked goods
  • Topicals like salves and lotion, which can relieve pain and inflammation in the area applied (but don’t get you high), and transdermal patches (meant to affect you systemically).

Is medical cannabis safe to use?

A 2015 study in The Journal of Pain looked at the safety of cannabis when used by patients with chronic pain over the course of a year. The researchers compared over 200 people with chronic pain using cannabis in Canada to a similar number of people with chronic pain who were not using cannabis. The patients were part of a monitored treatment program. They found that while medical cannabis users had an increased risk of side effects, “most were mild to moderate,” the authors write. The report concludes that cannabis “appears to have a reasonable safety profile.”

That’s not to say there aren’t risks to using medical cannabis. Cannabis can make anxiety or mood disorders worse in some people, according to a review. And it has been strongly linked to the risk of developing a psychotic disorder, such as schizophrenia, in those people already at genetic risk of such disorders. There is also some evidence that cannabis use has effects on brain development when used in adolescence.

Kevin Hill, MD, a psychiatrist at Beth Israel Deaconess Medical Center in Boston, Massachusetts, and at Harvard Medical School who has studied medical cannabis, spoke with HealthCentral via email about the safety of medical cannabis.

“Medical cannabis is as safe as many other medications that are used to treat chronic pain if used under the supervision of a physician,” Dr. Hill writes. “That’s where this gets tricky. Few physicians, for a host of reasons, are willing to recommend medical cannabis, so patients often turn to physicians who do nothing but crank out medical cannabis certifications all day.”

The best scenario for success, says Hill, is for medical cannabis to be used as part of a collaborative process between the patient and a physician who knows the patient well.

Is medical cannabis effective for chronic pain?

The short answer: yes. Among all conditions studied, chronic pain has the highest-quality scientific evidence to support the use of cannabis as an effective treatment.

The National Academies of Science, Engineering, and Medicine issued a comprehensive report in 2017 that reviewed cannabis research to come up with nearly 100 conclusions about the health effects of cannabis and cannabinoid use. Their top conclusion regarding cannabis’ therapeutic effects: “There is conclusive or substantial evidence that cannabis or cannabinoids are effective for the treatment of chronic pain in adults." The only other two conditions for which there is this, the highest level of evidence, are its use as an antiemetic (stops vomiting) for chemo and for muscle spasms in multiple sclerosis.

A review by Hill found that evidence exists for cannabis’ effectiveness at treating both chronic pain and neuropathic pain, a chronic, complex type of pain that often results from damaged, injured, or otherwise dysfunctional nerve fibers.

Regardless of the cause of the chronic pain, it is reasonable to conclude that cannabis is an effective treatment. You will still need to weigh the risks and speak with your physician to determine whether medical cannabis is right for your specific condition and medical history. And, cautions Hill, “it’s not a first-line treatment for chronic pain.” But if first-line and second-line treatments have failed, a trial of medical cannabis may make sense.

How do I find out more about medical cannabis?

If you think medical cannabis might be helpful for you to treat your chronic pain and you live in a state with a medical marijuana program, begin by learning about the laws around your state’s program. Each state is different in how they structure their medical marijuana program. In some, you’ll have to go to a select number of approved physicians who can prescribe cannabis. In others, any physician with whom you’ve established a relationship of a certain length of time (for example, three months in Vermont) can write you a prescription.

Caution: the fact that they can prescribe doesn’t mean that they understand how to help you use medical cannabis effectively and safely. The dispensaries are generally not able to provide this guidance, either. You may wish to find a cannabis-friendly physician who specializes in the use of medical marijuana to treat chronic pain and other ailments. More physicians with this special focus are appearing in states with legal medical marijuana programs.

If you’re taking any other medications for pain, including opiates, it’s very important you check in with your physician before changing your medication dosage or schedule, and before trying cannabis for your pain.

See more helpful articles:

13 Sizzling Questions About Marijuana and Chronic Pain

Medical Marijuana: Q&A With Sue Rosen, RN, Legal Liaison