Researchers from McGill University in Montreal reviewed the evidence.

First, the details.

• Safety studies of medical cannabinoids published over the past 40 years were reviewed.
• After excluding articles on recreational cannabis, 31 studies (23 randomized controlled trials and 8 observational studies) of medical cannabis use were analyzed.

And, the results.

• In the 23 randomized controlled trials, the duration of cannabinoid exposure was about 2 weeks (range 8 hours to 12 months).
• 4779 side effects were reported.
• 97% were not serious.
• Among 164 serious side effects, the most common included relapse of multiple sclerosis (13%), vomiting (10%), and urinary tract infection (9%).
• The rate of nonserious side effects was higher among those assigned to medical cannabinoids vs controls.
• The rates of serious adverse events did not differ between the groups.
• Dizziness was the most commonly reported nonserious side effect (16%) among people exposed to cannabinoids.

The bottom line?
The authors concluded, “Short-term use of existing medical cannabinoids appeared to increase the risk of nonserious adverse events.”

By comparison, “The risks associated with long-term use were poorly characterized… High-quality trials of long-term exposure are required to further characterize safety issues related to the use of medical cannabinoids.”

6/17/08 21:14 JR