Cannabinoid Hyperemesis Syndrome (CHS) is a relatively newly discovered illness. First documented in 2004, there has been limited research into the condition, which can cause stomach pain and prolonged bouts of vomiting in heavy cannabis users.

What is CHS?

Hyperemesis is an episode of severe vomiting, often lasting for hours. While there can be many causes, ranging from food poisoning to a heart attack for single episodes, to cyclic vomiting syndrome for repeated attacks, CHS is linked to cannabis use. Mild symptoms of CHS have traditionally been called a whitey (or white-out) which is a term for when a recreational drug user, as a direct or indirect result of drug use (usually cannabis), begins to feel faint and vomits¹Perisetti, Abhilash, et al. “Cannabis Hyperemesis Syndrome: An Update on the Pathophysiology and Management – PMC.” PubMed Central (PMC), 16 Sept. 2020, www.ncbi.nlm.nih.gov/pmc/articles/PMC7599351..

The first paper published on it tracked several patients at a hospital in South Australia who had presented with recurrent bouts of severe vomiting. The research identified the link with cannabis. All the patients had been heavy cannabis users. A group who stopped using cannabis all saw their symptoms end, and those who continued to abstain did not have a recurrence. Those that, after a period, resumed cannabis use, also saw a resumption of their hyperemesis.

Subsequent studies have found similar cases. And, although some studies were small, often with only a handful of subjects, the findings have been consistent. CHS is now a formal diagnosis and some doctors and hospitals report seeing an increase in presentations.

Who can get cannabinoid hyperemesis syndrome?

As a relatively new condition, CHS is not fully understood and it’s still not clear how prevalent it is. Although it appears comparatively rare, this might be down to a lack of awareness in the medical community. Research in the British Medical Journal suggested that around 6% of the emergency room presentations for vomiting²Chocron, Yaniv, et al. “Cannabinoid Hyperemesis Syndrome | the BMJ.” The BMJ, 1 Jan. 2019, www.bmj.com/content/366/bmj.l4336. episodes were likely to be CHS, but many were misdiagnosed, and patients frequently referred for expensive diagnostic tests.

Other research, into a large number of regular and heavy cannabis users — who had used the drug daily, or close to daily, for over a year — found that around one-third reported experiencing CHS symptoms.

There has been some suggestion that the syndrome is becoming more common, linking this to liberalized laws around cannabis use in some places. However, it has not been possible to eliminate other potential causes for a perceived increase in cases, including wider medical awareness, more accurate diagnoses, or patients being more honest about recreational drug use.

The main risk factor is prolonged, regular, cannabis use. The diagnostic criteria require long-term use on, at least, a weekly basis. In practice, cases most often occur after several years of daily, or near-daily use. It also appears that men are more likely to have CHS, but it has not been established if this is down to usage habits, or if gender affects susceptibility.

However, the actual cause is not known and there is a disconnect between the prevalence of cannabis use and the number of people who go on to develop CHS. Some researchers have suggested that this may point to a genetic component, which means some people are more susceptible to the syndrome. Much of the scientific speculation has been on the anti-nausea effects cannabinoids usually have, and whether these have other effects that, over time, cause the hyperemesis³Habboushe, Joseph. “The Prevalence of Cannabinoid Hyperemesis Syndrome Among Regular Marijuana Smokers in an Urban Public Hospital.” The Prevalence of Cannabinoid Hyperemesis Syndrome Among Regular Marijuana Smokers in an Urban Public Hospital, onlinelibrary.wiley.com/doi/full/10.1111/bcpt.12962. Accessed 11 Oct. 2022..

What are the effects of cannabinoid hyperemesis syndrome?

The most obvious effects of CHS are the prolonged and severe vomiting episodes accompanied by abdominal pain. Indeed, the combined effect of this has led to the term ‘scromiting’ being coined to describe the disease: a combination of screaming and vomiting to highlight the two main symptoms. However, there are a number of other direct and indirect symptoms.

CHS usually has a prodromal phase before the vomiting episodes start. This can last months, or even years. During this phase, an individual can have symptoms like a general morning sickness and some discomfort. These are likely to be mild and, therefore, disregarded. Indeed, some people may actually increase cannabis use, believing it will help alleviate the nausea and discomfort.

When CHS fully develops, individuals will experience the hyperemetic phase. These will be the prolonged bouts of vomiting and abdominal pain — the scromiting. They are likely to exhibit other symptoms that are common with vomiting bouts, such as dry heaving, dehydration, food aversions and weight loss⁴Lapoint, Jeff, et al. “Cannabinoid Hyperemesis Syndrome: Public Health Implications and a Novel Model Treatment Guideline – PMC.” PubMed Central (PMC), 8 Nov. 2017, www.ncbi.nlm.nih.gov/pmc/articles/PMC5851514..

Compulsive bathing is also frequently observed in CHS. This appears to help alleviate the abdominal pain. As with CHS generally, the mechanism is not understood, although it’s believed that CHS may affect the brain’s ability to regulate body temperature. Whatever the cause, patients with CHS have been observed bathing up to 15 times a day, even getting up multiple times during the night to bathe. In some cases, the water temperature used has been so high it caused scolding injuries.

The recovery phase usually follows the hyperemetic phase, largely because the patient naturally ceases cannabis use. The CHS symptoms will usually resolve quickly after cannabis use has stopped, typically within ten days. However, if cannabis use resumes, then the individual is likely to begin a cycle of hyperemetic and recovery phases.

The long-term effects of CHS are unknown. However, there are known risks that are associated with vomiting. These can include dehydration and malnutrition, weight loss, tooth decay, and esophageal problems, like Mallory-Weiss syndrome. It is possible that the dehydration caused can cause kidney failure, although this is very rare.

What is the treatment for CHS cannabinoid hyperemesis syndrome?

There are few treatment options for CHS, and they are limited to alleviating the symptoms. In severe cases, this might include an intravenous drip to address fluid loss. Pain relief can be difficult, since the side effects of many painkillers make them unsuitable for patients with hyperemesis. Some case-studies have suggested anti-psychotic medication can provide relief, but wider studies have had mixed results.

Many doctors use capsaicin cream, a topical analgesic derived from chili peppers, to ease the abdominal pain. The theory is that it triggers a similar response to hot water bathing, although, again, research has not been conclusive.

There is no known treatment for CHS itself other than to cease cannabis use. Although most research into CHS treatments has been inconclusive, the one consistent finding has been that cessation of cannabis use — and remaining abstinent — will provide complete relief from CHS and its symptoms.

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