Marijuana is enjoying an unprecedented level of acceptance in the United States, but along with the medical and social benefits of legalization, doctors are also learning about side effects that haven’t received much coverage. One of these effects is a particularly nasty one that gives heavy marijuana users extreme nausea and vomiting, which doctors have only recently characterized as cannabinoid hyperemesis syndrome (CHS).

Hyperemesis, which literally means “excessive vomiting,” sounds unpleasant enough as it is, but it actually undersells how bad CHS can be. Exact experiences vary, but some patients describe extreme abdominal pain, and many report being incapacitated by the physical distress. One patient told the New York Times on Thursday that the pain is worse than a broken bone. There are only two ways to get reliable relief: quitting marijuana or, strangely, taking hot showers. In fact, in a paper published January 2018 in the journal Basic & Clinical Pharmacology & Toxicology, researchers report that shower-induced relief is a major marker of CHS.

showerhead
Doctors report that, besides quitting marijuana, hot showers offer the most reliable relief from cannabinoid hyperemesis syndrome.

Doctors don’t know exactly why CHS occurs, but they suspect it has something to do with cannabinoids’ effects on the body’s endocannabinoid system. This system, which is involved with a wide array of bodily processes, affects appetite and the ability to feel satiated by food. The endocannabinoid system is also involved in pain management. Doctors hypothesize that hot showers offer relief by refocusing the patient’s pain perception away from their physical discomfort. They haven’t identified any signs that predict a person’s likelihood of developing CHS.

As unpleasant as it is, CHS definitely isn’t the only side effect of marijuana. Studies have shown that marijuana use can exacerbate underlying psychological issues in some people, and it’s likely that we’ll see patients report issues like these more frequently in states where marijuana has become legal. As Inverse reported on CHS in 2016, doctors very rarely saw the condition before liberalization, but now the rising tide of cannabis law reform has brought CHS to the forefront.

“Marijuana is probably safer than a lot of other things out there, but the discussion about it has been so politicized and the focus has been on the potential benefits, without looking rigorously at what the potential downside might be,” Dr. Joseph Habboushe, an assistant professor of emergency medicine at New York University Langone and the first author on the January paper, told the New York Times. “No medication is free from side effects.”

Moving forward, doctors have a lot to learn about marijuana and its biologically active compounds. While in a lot of ways marijuana can seem like a godsend to patients who don’t respond to other therapies, we’ll need more research to tell us about the relative risks of medical marijuana.