Edible marijuana products are a small slice of cannabis sales in Colorado, but were linked to a large proportion of cannabis-related emergency room visits in the state, according to a study published on Monday.

From January 2012 to December 2016, edibles accounted for 10.7% of emergency room visits attributable to cannabis use at the University of Colorado Health emergency department in Aurora, Colorado, though they only accounted for 0.32% of cannabis sales in that same period, according to the Annals of Internal Medicine study.

This is not simply because people are taking larger numbers of edibles to compensate for how much longer it takes to feel the effects than when cannabis is inhaled, said lead researcher Dr Andrew Monte.

“It was a striking thing,” Monte, an associate professor of emergency medicine at the University of Colorado, told the Guardian. “It wasn’t like these people were taking 100mg or 500mg of cannabis edibles. These were relatively lower doses.”

Monte said the adverse impact of edibles can last longer and be more intense than people expect.

“If you smoke and you have a brief amount of hallucination, but then it goes away pretty quickly, you may not come to the emergency department,” Monte said. “But if you develop psychosis and it’s lasting for hours, you might come to the emergency department.”

Overall, visits tied to both inhaled and edible cannabis use were mostly for gastrointestinal issues, intoxication and psychiatric symptoms. Edible cannabis led to more acute psychiatric events and cardiovascular symptoms than inhaled cannabis.

The rates at which people are hospitalized for cannabis use in Colorado are still far lower than alcohol-related hospitalizations. “Many, many people use cannabis without ending up in my emergency department,” Monte said.

Colorado’s recreational marijuana market opened at the start of 2014, ushering in a new era of research on the impact of legal cannabis use.

Monte said that increased availability of any drug will cause more adverse drug events.

“So, this is us sort of learning what those adverse drug events are, which routes of exposure are more likely to lead to adverse drug events, so we can actually advise people on how to use cannabis safely,” Monte said. “And also potentially put some more guidelines around the things that are most dangerous and I would say that in this study, it’s edibles.”