Pharmaceutical-grade cannabis may have some pain-reducing effects in fibromyalgia patients, but those results vary depending on the chemical contents of the specific plant.
The study with that finding, “An experimental randomized study on the analgesic effects of pharmaceutical-grade cannabis in chronic pain patients with fibromyalgia,” was published recently in the journal Pain.
Cannabis is increasingly considered as a pain medication, particularly because it may be an alternative to opiates.
In order to test the effects of pharmaceutical-grade cannabis in patients with chronic pain caused by the fibromyalgia (FM) syndrome, investigators recruited 20 women who were experiencing chronic pain (defined as an average of at least 5 on a pain scale from 1 to 10 for most of the day).
The patients participated in the study on four separate occasions; each time, they were given a different variety of cannabis.
The cannabis plant has hundreds of components that have a biological effect, and the two most well-known are tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is primarily responsible for the cannabis “high.” CBD doesn’t cause a high, but there’s evidence it can have other effects, including altering mood.
The four strains used had different amounts of those two compounds, i.e., high THC/low CBD, low THC/high CBD, high THC/high CBD, and a control strain (placebo) that had neither THC nor CBD.
The patients inhaled the cannabis fumes with a vaporizer and were then monitored and given tests for pain. The researchers also took blood samples from patients to measure the amount of THC and CBD in their bloodstreams.
The researchers administering the test and the patients were both blind to which strain was being used on any of the four visits. However, the researchers did note that most (13 of 20) patients correctly guessed when they had been given the placebo strain.
All 20 patients completed the study. Both of the THC-high strains caused a slight decrease in sensitivity to a pain test involving pressure. However, the effects in an electrical pain test weren’t different between the test strains and the control.
Most patients reported some decrease in spontaneous pain after being given all of the varieties, including the control, which is suggestive of a fairly strong placebo effect. This decrease was correlated with the magnitude of drug high.
The researchers did note that the placebo was cannabis only lacking THC and CBD. So, it’s possible there are other compounds in the plant that affect pain, meaning this lack of difference might not be entirely a placebo effect. More research is needed to figure this out.
“(…) the placebo cannabis variety used in our study is best considered an active placebo. Hence, the observation of an appreciable placebo effect in the relief of spontaneous pain is not surprising,” the researchers wrote.
Interestingly, the researchers noted that THC levels in the blood were higher after patients received the high THC/high CBD strain than in the high THC/low CBD, even though THC levels in the plants were comparable. The researchers think this might be because CBD can be converted into THC, which has been observed in animal studies. Again, more research is needed to be sure.
The patients did experience some side effects, primarily those related to the process of inhalation (coughing, sore throat, etc.), as well as some nausea and dizziness. Most patients also reported disliking the feeling of the drug high, a fairly common observation in chronic pain patients treated with psychotropic medications.
“Our experimental study was not designed to provide direct evidence for the clinical use of cannabis in [fibromyalgia] but may be used to design future clinical trials,” the authors stated. As always, more research will be needed to determine exactly how cannabis could be used to most effectively help patients control pain.