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The department is filled with the sound of retching as you approach the room of the next patient, a 29-year-old male with nausea, vomiting, and abdominal pain. Although the patient received ondansetron in the ambulance, he is still uncomfortable. He reveals that he has had similar episodes of generalized abdominal pain, nausea, and vomiting in the past. Taking a hot shower sometimes helps. He has not had fevers or diarrhea, and his abdominal exam is benign. Before exiting the room, you have one remaining question to ask: Does he use marijuana, and if yes, how often? 

Cannabinoid Hyperemesis Syndrome

This is a classic case of cannabinoid hyperemesis syndrome (CHS). The treatment, cessation of marijuana use, will not provide immediate relief in the emergency department. So what do you do in the meantime?

CHS, first characterized in 2004, presents similarly to other cyclic vomiting syndromes.¹ CHS is characterized by nausea, vomiting (classically described as cyclic), and abdominal pain in patients with chronic use of marijuana. Patients frequently report that hot showers relieve symptoms, and some have described compulsive bathing.² For some, CHS seems at odds with the long-touted antiemetic properties of tetrahydrocannabinol (THC). How could an antiemetic cause a cyclic vomiting syndrome? 

The mechanism underlying CHS is not entirely clear, but it is believed that the gastrointestinal effects are a result of activation of cannabinoid 1 (CB1) receptors, which inhibit gastric emptying and motility. With chronic use, THC can at times emerge from adipose tissue and enter the bloodstream, potentially contributing to a bout.

In many instances, ondansetron does not suffice in treating CHS.³ Fortunately, the butyrophenones—haloperidol and droperidol—have emerged as promising treatments.  Reports of the success of haloperidol and droperidol have largely been documented in case series and retrospective studies.⁴ These medications have a track record of efficacy in postoperative nausea and migraine headaches, so it is credible that they might be effective in CHS. Until recently, the best available evidence was a retrospective study of patients who received droperidol, most of whom received 0.625 mg or 1.25 mg. Patients who received droperidol had a shorter length of stay (6.7 hours versus 13.9 hours).⁴ However, we now have a small prospective randomized trial comparing haloperidol to ondansetron in CHS, which was published in the Annals of Emergency Medicine.