Heavy marijuana users may experience recurring bouts of severe nausea, vomiting, and abdominal pain, a condition known as cannabinoid hyperemesis syndrome (CHS). Now, doctors say that the symptoms can be rapidly relieved by taking hot showers, although no one is sure why this works.

The condition was first recognized in 2004, and since then more and more cases have been reported, probably as marijuana users became more comfortable talking about it to their doctors. According to one recent study, about one-third of heavy smokers, defined as individuals who use marijuana more than 20 times per month, experience CHS. By extrapolating these results, researchers estimate as many as 2.7 million Americans could be affected by the syndrome.

“After marijuana was legalized in Colorado, we had a doubling in the number of cases of cyclic vomiting syndrome we saw,” many probably related to marijuana use, Dr. Cecilia J. Sorensen, an emergency room doctor at University of Colorado Hospital told The Miami Herald.

The condition can be quite serious, with some patients describing excruciating symptoms that last for up to 12 hours. Taking anti-nausea drugs, anti-anxiety medications, and antidepressants — as some patients have tried — does not seem to work to relieve the symptoms. Instead, CHS can be treated by quitting marijuana, or by taking a hot shower, according to the latest findings by researchers at NYU Langone and the Bellevue Medical Center.

The findings are based on interviews of 2,127 adult emergency room patients under 50 at Bellevue, a large public hospital in New York City. Of the 155 patients who said they smoked marijuana at least 20 days a month, 51 heavy users said they had during the past six months experienced nausea and vomiting that were specifically relieved by hot showers. The findings appeared in the journal Basic & Clinical Pharmacology & Toxicology.

Because symptoms of CHS often do not respond to drug treatment and the risk of misdiagnosis is significant, the authors of the new study caution doctors to be more mindful of the condition when running diagnoses. Sometimes, patients can go through several rounds of ER visits, hospitalization, tests (including MRIs), and inefficient treatments before doctors realize the problem is ‘smoking too much pot.’

As to what causes CHS, scientists don’t have a definite answer yet. It is possible, however, that long-term heavy marijuana use can mess up the body’s endogenous cannabinoid system — a collection of cell receptors and corresponding molecules, without which psychoactive compounds in marijuana like THC would never work. Our bodies naturally produce endocannabinoids which are similar to some compounds found in marijuana and play an important role in easing pain.

By having THC around all the time, this system may get disrupted. Hot showers can relieve symptoms because it triggers a different sensory signal, distracting the body from the pain signal. This is just an untested hypothesis, however — and whatever may be causing CHS, at least there’s a reliable cure: quitting marijuana. Previously, the same team of researchers NYU found that 97 percent of people with cannabinoid hyperemesis syndrome stopped showing symptoms after they gave up smoking cannabis.

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