Cannabinoid Hyperemesis Syndrome Presenting as Postoperative Nausea and Vomiting in a Chronic Cannabis User: A Case Report.

Cannabinoid hyperemesis syndrome (CHS) is a paradoxical condition seen in chronic cannabis users, marked by recurrent nausea, vomiting, and abdominal discomfort. Although more widely recognized in emergency medicine, CHS remains underdiagnosed in the perioperative setting, where its symptoms may be misattributed to common postoperative phenomena such as anesthetic effects, opioid-induced nausea, or surgical complications. This diagnostic gap can delay appropriate management and lead to unnecessary interventions. We report the case of a 40-year-old woman with a two-year history of daily cannabis use who underwent a laparoscopic hysterectomy, mid-urethral sling placement, and pelvic organ prolapse repair. In the immediate postoperative period, she experienced persistent nausea and vomiting despite the administration of multiple antiemetics, including ondansetron and metoclopramide, and opioids for pain control. By postoperative day 2, vomiting occurred in discrete, refractory episodes despite continued pharmacologic management, prompting concern for an atypical cause. The patient was placed on nil per os (NPO) status, but symptoms escalated on postoperative day 3, culminating in a prolonged episode of emesis accompanied by hematemesis and hallucinations. At this stage, CHS was strongly suspected given her chronic cannabis use, clinical trajectory, and lack of response to standard therapies. Supportive care was intensified with intravenous hydration and electrolyte replacement for significant hypokalemia and hypophosphatemia. The patient's condition stabilized over the next 24 hours, with gradual resolution of symptoms and resumption of oral intake by postoperative day 4. She was discharged in stable condition with a tailored regimen of antiemetics, analgesics, and counseling on cannabis cessation. She abstained from cannabis throughout hospitalization. This case highlights a critical but underrecognized cause of refractory postoperative nausea and vomiting (PONV). In patients with a history of chronic cannabis use, perioperative teams should maintain a high index of suspicion for CHS when standard antiemetic regimens fail. Early identification not only prevents unnecessary diagnostic testing and extended hospitalization but also enables more effective patient education and targeted counseling. Broader awareness of CHS among surgical and anesthesia teams can improve outcomes through timely diagnosis, supportive care, appropriate discharge planning, and public health efforts to raise awareness of cannabis-related complications.