A study shows marijuana is sending more people to the emergency room in one large Denver hospital.

Inhaled weed caused the most severe problems. Marijuana-infused foods and candies also led to trouble.

Patients came to the ER with symptoms such as repeated vomiting, racing hearts and psychotic episodes. Nearly a third of patients were admitted to the hospital, indicating severe problems.

FILE - This Thursday, June 2, 2016 file photo shows lime-flavored cannabis-infused gummy candy in Portland, Ore., on the first day recreational marijuana users could legally purchase marijuana edibles and oils in the state. A study shows marijuana is sending more people to the emergency room in one large Denver hospital. Inhaled weed caused the most severe problems. Marijuana-infused foods and candies also led to trouble.(AP PhotosGillian Flaccus)

FILE - This Thursday, June 2, 2016 file photo shows lime-flavored cannabis-infused gummy candy in Portland, Ore., on the first day recreational marijuana users could legally purchase marijuana edibles and oils in the state. A study shows marijuana is sending more people to the emergency room in one large Denver hospital. Inhaled weed caused the most severe problems. Marijuana-infused foods and candies also led to trouble.(AP PhotosGillian Flaccus)

The researchers analyzed records from University of Colorado Health Emergency Department from 2012 through 2016.

They found a three-fold increase in marijuana cases since the state became the first to allow sales of recreational marijuana in January 2014. Lead author Dr. Andrew Monte says marijuana can be used safely, but can also be dangerous.

The study was published Monday in Annals of Internal Medicine.