The news that the states of Washington and Colorado have legalized use of marijuana is a good reason to review the plusses and minuses of the drug. Our most recent article on medical use of marijuana was published in The Medical Letter in 2010 (January 25). At that time, 14 states permitted some medical use of marijuana.
Marijuana is modestly effective for relief of nausea and pain, depending on the severity of the symptoms and the dose of the drug. It is not clear that it is effective for treatment of intractable cancer pain, which was the use advocates of legalization often highlighted. Dronabinol, which is a synthetic form of the main active ingredient in marijuana, has been approved by the FDA for years for treatment of cancer chemotherapy-induced nausea and vomiting. For the severe nausea and vomiting associated with some cancer chemotherapy agents, other drugs are more effective.
How safe is marijuana, anyway? Well, it probably will not cause as much trouble as alcohol, but there are some hazards that we know about and, as always, some that will surprise us by their appearance. Remember that it took decades to realize that aspirin could cause bleeding or tetracycline could cause (in young children) brown teeth. Marijuana used alone apparently is not lethal, no matter how much someone smokes or ingests. Used with alcohol or other sedatives, we can’t be so sure. Marijuana alone can cause dry mouth, sedation, orthostatic hypotension, and ataxia. In the long term, inhaling the products of combustion of another plant has not had a good track record, and there are no data to convince us that marijuana could not give us more of the same.
For aging boomers seeking to relive the exciting days of their youth, legal marijuana may be especially troublesome. Anxiety, tachycardia, agitation and confusion occur commonly in older users and may impair their driving skills. The definition of DUI may have to be broadened. Will it all be worth it? That is not for us to say.