TORONTO — A benchmark study has found that patients who use medical marijuana to treat chronic pain don’t have more serious side-effects than sufferers who don’t use the herb.
Dr. Mark Ware, the Montreal pain specialist who led the national study, says medical cannabis appears to have a reasonable safety profile when taken by patients who are experienced users.
The four-year study followed 215 adults with chronic non-cancer pain who used medical cannabis and compared them to a control group of 216 chronic pain sufferers who were not marijuana users.
The cannabis group was given access to herbal cannabis containing 12.5 per cent of the active ingredient THC from a licensed cannabis producer.
Researchers found significant improvement in pain levels, mood and quality of life among pot users compared to the control group, and no evidence of harmful effects on cognitive function.
However, cannabis users had an increased risk of non-serious side-effects such as headache, nausea, dizziness and respiratory problems associated with smoking.
“It is important to note the limitations of the study,” said Ware. “Patients were self-selected, not randomized, and most were experienced users. So what we are seeing is that it appears to be a relatively safe drug when used by people who have already determined that it helps them.
“We cannot draw conclusions about safety issues of new cannabis users.”
Ware said the study, published online in The Journal of Pain, should help doctors counsel chronic-pain patients about medical marijuana’s effectiveness and its potential side-effects.