Though many who suffer chronic pain will tell you that smoking pot can help dull the pain, there has been little hard medical research into whether it really is effective.
Now, a new randomized, placebo-controlled clinical trial, appearing in the Canadian Medical Association Journal, shows that marijuana really can bring pain relief and improved sleep to those in chronic pain.
Dr. Mark Ware, director of research at the Alan Edwards Pain Management Unit of the McGill University Health Centre, led a team who studied the pain-relieving effects of smoking cannabis in 21 people with "chronic neuropathic pain": those who had constant nerve pain, caused by trauma or surgery.
All had suffered the pain for at least three months, had failed to get effective relief from other medications, and reported an average weekly pain intensity score greater than 4 on a 10-point scale.
To ensure that the participants couldn't tell who was smoking real marijuana and who was smoking a placebo, the patients were given a special pipe and 25-milligram capsules of a substance to be lit and inhaled once. The capsules contained either 2.5 per cent, 6 per cent or 9.4 per cent tetrahydrocannabinol (THC), which is the active ingredient in marijuana. The placebo pill contained no THC.
They smoked the pipe three times daily for five days in each cycle, followed by a nine-day period without marijuana. They continued this over two months, rotating through all four strengths of THC.
The researchers found that those smoking the tabs with the highest potency, 9.4 per cent, saw their average pain "significantly reduced" compared with those smoking the placebo. The patients also reported improvements in sleep quality and anxiety.
Because the dosages were fairly small compared to what "recreational" pot smokers would receive, most participants said they didn't get "high" from the drug; "euphoria" was reported on only three occasions.
The researchers note that off the one puff, the blood levels of THC in the study participants reached only about 45 nanograms per milliliter, whereas most pot smokers would see levels reach 100 ng/mL and higher.
"We used a small dose for two reasons," Ware explained to 麻豆影视 Channel. "One was to reduce the likely effect on the lung; it was a smoked product after all, so we wanted minimize the possible effects on the lung and respiratory track.
"The second reason was to minimize the possible psychoactive effects. We were not using this as a way to get people high but to try to ameliorate a very devastating symptom of chronic neuropathic pain."
Some of the patients did report side effects, including dizziness, numbness and a burning sensation in areas of neuropathic pain.
The researchers note that while cannabis has been used to treat pain since the third millennium B.C., the pain-relieving effects of the drug remain controversial in the medical community. Further study on whether the drug really works is needed, the researchers said, given that at least 10 per cent of patients with chronic non-cancer pain and other conditions have tried using marijuana to relieve pain.
The researchers say they would like to see larger and longer studies on marijuana, using higher potencies and flexible dosing to see if pain levels can be reduced even further.
"What I hope this study will do is highlight for patients and physicians that cannibinoids -- the active ingredients in marijuana -- are a legitimate contribution to pain management and should be considered as one option when you are trying to treat chronic pain," Ware said.
In an accompanying editorial, Dr. Henry J. McQuay of Oxford University, notes that the results are important in light of the fact that patients interested in the pain relief offered by medical marijuana have seen only a "trickle" of evidence to prove the claims that the drug works.
