PAIN+ CPN

Doctor, I have heard that marijuana can be used to treat pain.

Marijuana (cannabis) may be effective in reducing pain for some people, but the evidence to support that it works is weak. More research is needed.

What is the evidence?

SUMMARY OF FINDINGS

Cannabis vs other treatments or placebo for reducing pain intensity

Pain Condition

(length of treatment with cannabis)

Number of Studies*

Proportion of people with

30% reduction in pain intensity

Quality of Studies

Cancer pain

(2 to 5 weeks)

2

No difference

from control group

very low

Neuropathic pain

(at least 4 weeks )

4

No difference

from control group

low

*only pain conditions with more than one study that provided treatment for at least 2 weeks are reported here

control group: placebo or another pain treatment (e.g. naproxen or codeine)


What kind of study was this?

This was a systematic review of 36 studies published up to April 2019.

Who? The studies included 7,217 people with a range of pain conditions (neuropathic, cancer, post surgery, multiple sclerosis, carpal tunnel syndrome, chronic prostatitis/pelvic pain, back pain). Included studies had to enroll at least 30 people.

What? The studies compared cannabis (different types: oil, smoked, pill ) with another type of pain treatment or with placebo.

Cannabis

vs

Placebo or another treatment

Cannabis (including THC, PEA, nabiximols, dronabinol) taken by any route (inhaled, by mouth)

Frequently given together with other pain medications (e.g. ibuprofen, naproxen, codeine)


Another pain treatment: naproxen or codeine


Placebo: A pill/needle/lotion containing an inactive substance that has no effect on the outcome. Sometimes, it is referred to as a "sugar pill."



Why was this research done?

Cannabis has become popular for treating pain over the last few years. The reviewers wanted to update the evidence supporting that cannabis is good at reducing pain. They found mostly small studies that tested different types of cannabis over different periods of time (some oils, some smoked and some in pill form). There were also other problems with how the studies were done that raise concerns that additional studies might come to different conclusions. Overall, they found that the evidence supporting cannabis as a pain reliever was limited and of poor quality. That doesn't mean cannabis won't relieve pain for some people, but so far, it doesn't work well for most people. There are still more questions than answers so more research is needed.


This Evidence Summary is based on the following article:

Fisher E, Moore RA, Fogarty AE, et al. Cannabinoids, cannabis, and cannabis-based medicine for pain management: a systematic review of randomised controlled trials. Pain. 2020 May 18. doi: 10.1097/j.pain.0000000000001929. PubMed

Published: Monday, December 7, 2020
Last Updated: Tuesday, July 13, 2021