Does Marijuana help with pain?  What does science know so far?

Here is the video from “One Minute Medical School” that inspired me to dig into the research on the use of cannabinoids for fibromyalgia and chronic pain (see 0:58):

And by “cannabinoids”, I’m not ONLY talking about the medications Cesamet/Nabilone (tetrahydrocannabinol – THC), Marinol/Dronabinol (cannabidiol – CBD), and Sativex (nabiximols – THC & CBD); but also the use of marijuana for medical purposes, as well as the body’s naturally occurring “endocannabinoids” that affect the cannabinoid receptors in the body.

I discussed these different types of cannabinoids in a previous blog post called “Medical Marijuana and Cannabinoids (and hemp seed recipes)”

(Sorry, I’m not diving into the legalities or politics, just the science…)

In terms of pain:

Currently available agents (e.g. antidepressant and anticonvulsant analgesics, opioids and nonsteroidal anti-inflammatory drugs) are inadequate to control all pain or are associated with limiting side effects (e.g. most problematic being sedation with the antidepressant and anticonvulsant group, constipation with the opioids and gastrointestinal and cardiovascular effects with the NSAIDs).

There is a critical need for new treatments.

In this context, many people with chronic pain are turning to other therapies including cannabinoids. Due to patient demand, several nations (or states within countries) have developed programs to allow people with serious health conditions to access cannabis (marijuana) for medicinal purposes. Most of these programs (e.g., Canada, Israel, Netherlands, several US States) require physician or nurse practitioner support for the individual patient to be approved for access. Medical professionals have called for more research regarding both potential therapeutic and adverse effects of cannabinoids.(1)

And more research is needed – especially good quality research including randomized controlled clinical trials with enough people enrolled.  Several studies published in the past year have reviewed the research to date, and have noted an unfortunate lack of good quality studies.

Here’s a summary of several reviews published in 2015, and what they’ve found:

• This review describes cannabinoids as “safe, modestly effective analgesics”.(1)
• Another one says that “some studies thus far have shown evidence to support the use of cannabinoids for some cancer, neuropathic, spasticity, acute pain, and chronic pain conditions”.  It concludes that “the strongest evidence in support of cannabinoids for pain appears to be for cancer-related pain … Effects on neuropathic pain such as in HIV, MS, and post trauma have also shown positive results. Our literature review showed no improvement to mild improvement in acute pain and spasticity. However, chronic pain results were more promising with some studies showing statistically significant reductions in pain and quality of sleep.”(2)
• This article looked at cannabis for use in headache and found that it “may have a therapeutic role for a multitude of diseases, particularly chronic pain disorders including headache. …  Despite the limited evidence and research suggesting a role for cannabis and cannabinoids in some headache disorders, randomized clinical trials are lacking and necessary for confirmation and further evaluation.”(3)
• Another 2015 review found “moderate-quality evidence to suggest that cannabinoids may be beneficial for the treatment of chronic neuropathic or cancer pain (smoked THC and nabiximols) and spasticity due to MS (nabiximols, nabilone, THC/CBD capsules, and dronabinol).”(4)
• Finally, this article created a table of “Clinical Effectiveness of Cannabinoids”.(5)  Specifically in terms of pain, it says that cannabinoids are effective for several types of chronic pain (central chronic pain/painful spasms refractive to opiods, chronic pain associated with cancer and rheumatoid arthritis, and neuropathic pain; but it’s not been shown to be effective for acute pain).  See Table 1 for a summary of its effectiveness for pain, as well as non-pain issues as well.(5)

Of course, there will be individual patients who’ve benefited from marijuana, and that could be you, but other than the limited published research and the few approved medicines on the market, there is still not enough strong scientific evidence that cannabis works very well, with minimal side effects, for different kinds of pain in very many people.

See the chart in reference 6 to understand the strength of different types of scientific evidence.(6)

I’m going to dive into the adverse effects and safety concerns of medical marijuana products in next week’s blog post, so stay tuned!  Today, I’m just looking at the scientific evidence for how well it’s been shown to work for pain.

Approved marijuana-based medications

Cesamet/Nabilone (synthetic analogue of THC)

Nabilone was originally approved by the FDA 25 years ago to help with nausea and vomiting from chemotherapy, and is also approved for AIDS-associated wasting, as well as spasticity from spinal cord injury.(5)  It is approved in Canada for the same.  Nabilone has been shown to help with MS pain, “medication overuse headaches”, and diabetic neuropathy(1), but is not officially approved for those uses.

In terms of fibromyalgia, Nabilone was compared with amitritptyline and was shown to improve sleep, but not pain (considering that the pain was just 2.3/10 to begin with).(1)

Marinol/Dronabinol (CBD)

Dronabinol is also approved in the USA for nausea and vomiting from chemotherapy,(5) but it was withdrawn from the Canadian market in 2012.

Oral Mucosal Cannabis Spray (Sativex – Nabiximols – THC & CBD)

Sativex is a buccal spray (under the tongue or on the cheek) that was approved for use in Canada in 2005 to help relieve spasticity associated with multiple sclerosis (MS).  It also has conditional approval for neuropathic pain for patients with MS, as well as for severe pain in advanced cancer.(7)  It is not approved in the USA.

References:

(1)  Cannabinoids for the Treatment of Chronic Non-Cancer Pain: An Updated Systematic Review of Randomized Controlled Trials.

(2)  Medical Marijuana and Chronic Pain: A Review of Basic Science and Clinical Evidence

(3) Comprehensive Review of Medical Marijuana, Cannabinoids, and Therapeutic Implications in Medicine and Headache…What a Long Strange Trip It’s Been…

(4)  Cannabinoids for Medical Use: A Systematic Review and Meta-analysis

(5)  Effectiveness, Adverse Events and Safety of Medical Marijuana

(6)  A Rough Guide to Types of Scientific Evidence

(7)  Sativex Product Monograph, GW pharma Ltd. March 30, 2012.