“The first question he asked was if I was taking hot showers to find relief. When he asked me that question, I basically fell into tears because I knew he had an answer,” Crowder said.

The answer was cannabinoid hyperemesis syndrome, or CHS. It’s caused by heavy, long-term use of various forms of marijuana. For unclear reasons, the nausea and vomiting are relieved by hot showers or baths.

“They’ll often present to the emergency department three, four, five different times before we can sort this out,” said Dr. Kennon Heard, an emergency room physician at the University of Colorado Hospital in Aurora, Colorado.

“It is certainly something that, before legalization, we almost never saw,” Heard said. “Now we are seeing it quite frequently.”

Outside of Colorado, when patients do end up in an emergency room, the diagnosis is often missed. Partly because doctors don’t know about CHS, and partly because patients don’t want to admit to using a substance that’s illegal.