Researchers at the McGill University Health Centre (MUHC), McGill University and the University of British Columbia (UBC) have revealed in a new study that cannabis based medicines may not have major side effects, but do cause minor disturbances.
Many medical drugs contain compounds derived from the cannabis plant, or cannibinoids. And with the increase in the use of cannabinoid medications, there are increased concerns about their potential to cause negative side effects.
Researchers have now examined the nature of these potential adverse events in their study, which was based on the adverse events detailed in 31 separate clinical studies of cannabinoid medications conducted between 1966 and 2007.
Adverse events were categorized as either serious or non-serious; with serious adverse events defined as those leading to death, hospitalization or disability.
"Overall, we found an 86% increase in the rate of non-serious adverse events among the patients treated with cannabinoids compared to the patients in the control groups," said Dr. Mark Ware, a neurosciences researcher at the Research Institute of the MUHC and assistant professor in anesthesia at McGill's Faculty of Medicine.
Most of the events ranged in severity from were mild to moderate. A large number of non-serious adverse events observed affected the nervous system, mainly dizziness and drowsiness.
"Cannabinoids are used as medicines because they are neurologically active, so we expected to see some side effects such as these," said Tongtong Wang, a PhD candidate in epidemiology and biostatistics at McGill University.
Cannabinoids are known to treat chronic pain resulting from diseases such as cancer, multiple sclerosis, arthritis and fibromyalgia, and also to stimulate appetite and relieve nausea.
However, physicians must evaluate the possible benefits of treatment against the possible side effects in an overall attempt to improve the patient's quality of life.
"We have summarized the adverse events from these studies to help educate physicians and patients about the possible risks of medical cannabinoids. We cannot extend these results to smoked cannabis or recreational use. That will require further research," said Dr. Jean-Paul Collet, formerly at McGill's Department of Epidemiology, and now professor at University of British Columbia.
The study will be published in the latest issue of Canadian Medical Association Journal (CMAJ).