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Colorado has seen an influx of out-of-state visitors since marijuana became legal, first for medical use in 2000, and then available for retail sale in 2014. But one worrying side effect has been the uptick in the number of tourists ending up in the hospital, which Dr. Howard Kim first noticed during his medical residency at Denver Health Medical Center.

“We noticed that there seemed to be a lot of people coming into our emergency room with marijuana-related symptoms,” he said, and the number of out-of-state visitors seemed to be rising quickly. “So we wondered if the numbers would bear this out overall.”

The statewide analysis that Kim and colleagues conducted found that, indeed, the rate of out-of-state emergency room visits for marijuana-related symptoms rose 200 percent from 2012 to 2014. The increase was just 44 percent among Colorado residents over that same period, researchers report in a correspondence to the New England Journal of Medicine.


The reason for that gap, Kim and his colleagues suspect, is that educational media campaigns about safe use of marijuana have been targeted at Colorado residents. They suggest that health messaging at the marijuana dispensaries themselves might be better able to reach marijuana tourists.

Kim said he often saw patients who were in town visiting relatives or on business trips and would decide to try some marijuana.


These patients would then show up at the emergency room with anxiety, agitation, increased blood pressure, and heart rates, along with gastrointestinal distress and vomiting. While some people were admitted to the hospital for observation, most were usually released within a few hours.