Like any medicine, marijuana is more effective at treating some ailments than others. However, because research into its medical benefits is still a relatively young field, medical researchers are still parsing out which targets the drug has actually been hitting.
In an analysis of findings from nearly 80 randomized clinical trials, which included about 6,500 participants in total, researchers laid out the evidence for using cannabinoids — the main active ingredients in marijuana — to treat a variety of conditions. Overall, they found the strongest evidence for using cannabinoids to treat chronic pain and the weakest evidence for their use in treating anxiety. The work was published in the journal JAMA.
The researchers also caution that, like virtually any medication, medical marijuana presents some side effects — though no one who has even basic knowledge of marijuana's effects will be shocked to learn what the most common ones are.
"There is evidence to support the use of cannabinoids for the treatment of chronic pain and spasticity [a muscle condition associated with multiple sclerosis]. However, this needs to be balanced against an increased risk of side effects such as dizziness, dry mouth, nausea, sleepiness and euphoria," the study authors said in a statement.
Studies exploring the efficacy of cannabinoids in treating nausea and vomiting due to chemotherapy, sleep disorders, Tourette syndrome and aiding weight gain in HIV patients was more sparse. The evidence for cannabinoids' efficacy in treating anxiety and depression was of the lowest quality, the researchers report. However, it is important to note that the low quality of the evidence in these cases does not necessarily reflect a lack of efficacy.
"Most trials reported greater improvement in symptoms with cannabinoids compared to control groups, however, these did not always reach statistical significance. This may have been due to the small sample sizes of many of the included studies," the study authors said in a statement.
Furthermore, most of the studies were relatively old.
"We had more older studies than recent studies in our review: a third of the studies included in our review were published before 1990 and the median year of publication was 2004," the study authors said in a statement.
The researchers involved in this analysis are based in the United Kingdom at the University of Bristol. Across the United States, 23 states and Washington, D.C. have legalized medical marijuana use.
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