Coloradan emergency rooms are getting more and more familiar with cannabis-related injuries and ailments, according a study reported by The Cannabist. But the explanation isn’t as simple as more legal cannabis equaling more cannabis-related health problems.

The number of weed-related visits to the University of Colorado Hospital nearly doubled when recreational marijuana became legalized in the state, shooting up from 85 per 10,000 visits in 2013 to 168 per 10,000 in 2014, according data from the University of Colorado School of Medicine.

But research also shows that most of that uptick in dank-smelling hospital patients can be accounted for by visitors to Colorado, while the number of Colorado residents needing medical attention after puff-puff-passing did not significantly rise from 2013 to 2014.

Weed tourists can end up in the ER for a variety of reasons. “The number one difference between someone visiting and using marijuana and someone who lives here and using marijuana is that the person visiting has just gone to a much higher altitude and we know that’s attributed to a bunch of symptoms like passing out and nausea,” said Mason Tvert of the cannabis advocacy group Safer Alternative for Enjoyable Recreation.

“A lot of people do different things when they’re home versus when they’re on vacation,” Mike Van Dyke, of the Colorado Department of Public Health and Environment, told Cannabist. “Some people tend to do it overboard more when they’re on vacation, and that could also be playing a part.”

The most common reason for cannabis users to end up in the hospital is gastrointestinal complications, with psychiatric or cardiopulmonary symptoms as the runners up.

Many of these hospital visits probably aren’t actually caused by cannabis. Andrew Monte, assistant professor of emergency medicine and toxicology at the CU School of Medicine, points out that, “Realistically, these visits could have marijuana mentioned at one point if they came and had a heart attack and said they did smoke a week ago, that would be reflected.”

But the study still indicates that educating visitors about responsible ways to consume cannabis, particularly in concentrated forms like shatter or edibles, might keep some of these yokels out of Colorado hospitals in the future.