Doctors say chronic marijuana use may be linked to an illness known as CHS, or Cannabinoid Hyperemesis Syndrome. In recent years, the number of known cases doubled in Colorado.

Experts say CHS is caused by chronic or heavy use of marijuana, which means ingesting or smoking marijuana at least once a day.

The symptoms can be severe. Patients have reported intense, non-stop nausea and stomach pain that can sometimes last up to a month.

Dr. Kennon Heard, a physician with the University of Colorado Hospital, is one of several doctors studying the effects of CHS.

He and his team found that the number of hospital visits for CHS doubled since medical marijuana became prevalent. The study takes a closer look at more than 2,500 hospital visits. From 2008 to 2009, the study found there were 41 visits to emergency rooms for CHS. From 2010 to 2011, after what the study describes as the “post-liberalization” period for medical marijuana, the number jumped to 87 ER visits.

“We see them here on a daily to weekly basis,” Dr. Heard said. [Read more at 9 News]