Specifically, CHS takes the pattern of cyclical nausea, vomiting, and abdominal pain in the setting of chronic cannabinoid use. The abdominal pain tends to be mild and diffused. There are three phases of CHS: the prodromal phase, the hyperemetic phase, and the recovery phase. Prodromal phase
The prodromal phase is characterized by mild symptoms of CHS, including nausea, anxiety, mild discomfort, sweating, and increased thirst; symptoms are more severe in the morning. Prior to the use of compensatory exposure to hot water to treat symptoms, people sometimes increase their intake of cannabinoids in an effort to treat the persistent nausea they experience. This phase can last for months or even years. Hyperemetic phase
The hyperemetic phase is characterized by the full syndromal symptoms of CHS, including persistent nausea, vomiting, abdominal pain, and retching. Retching can occur up to 5 times per hour. Acute episodes of cannabinoid hyperemesis typically last for 24–48 hours. The symptoms experienced in this phase are cyclical, and can recur unpredictably in intervals of weeks to months. It is very difficult to take food or medicine by mouth during this stage, and patients may develop a fear of eating. Weight loss and dehydration due to decreased oral intake and vomiting are possible. It is during this hyperemetic phase that people with CHS are likely to present to the emergency department of the hospital for treatment.Treatment via hot water, sometimes for hours at a time, relieves symptoms for many patients, which can result in compulsive bathing or showering.
The use of hot water showers in the emergency department setting has been advocated in situations where topical capsaicin cream is unavailable, though the same precautions to hot water use (dehydration, burn injury) are required.The use of antipsychotics, such as haloperidol and olanzapine, have provided complete relief of symptoms in case-reports. The evidence for the use of benzodiazepines, such as lorazepam, has shown mixed results. Other drug treatments that have been tried, with unclear efficacy, include neurokinin-1 receptor antagonists, first-generation antihistamines (e.g. diphenhydramine), 5-HT3 receptor antagonists (e.g. ondansetron), and non-antipsychotic antidopaminergics (e.g. metoclopramide).Acetaminophen has shown some benefit in case reports for alleviating headaches associated with CHS. Opioids can provide some relief of abdominal pain, but their use is discouraged due to the risk of worsening nausea and vomiting. Epidemiology
As of 2017 a French pharmacovigilance program for drug users had received reports of 29 cases of CHS. At the time there were 113 case described in the international medical literature. CHS incidence is likely to have been substantially under-reported.In the United States, an analysis of data from the National Emergency Department Sample between 2006 and 2013 found an increase in emergency room attendees with vomiting who also had cannabis use disorder, to a rate of approximately 13 per 100,000 attendees. It is possible this rise, of around 5+1⁄2 times, may be affected by sampling bias, as initial awareness of CHS prompted more diligent questioning and recording of when such ER attendees were also cannabis users.The number of people affected was unclear as of 2015.