We present a 26-year-old white male with a chief complaint of nausea and vomiting. The patient described prodromal nausea followed by intractable vomiting for 2 days. Over the past 2 years he has experienced similar episodes occurring every 3 to 6 months. He has been hospitalized 5 times for this problem with no diagnosis given. There are no obvious precipitants. The symptoms consistently last 2 to 3 days and resolve with supportive care including intravenous fluids and antiemetics. The patient enjoys good health between the periods of sickness. He has never experienced coffeeground emesis or hematemesis. His past medical history is significant for attention deficit disorder and cholecystectomy. He takes no prescription medications. Social history is remarkable for tobacco abuse, binge drinking on weekends, and daily marijuana use. He is unemployed. His family history is unremarkable.Physical examination at the time of admission was notable for tachycardia, orthostatic hypotension, and hypoactive bowel sounds. Otherwise physical examination was normal.Diagnostic testing done on admission was notable for white blood cell count of 25,000, hemoglobin of 17.3, blood urea nitrogen 18, creatinine 1.4, aspartate aminotransferase (AST) 64, and alanine aminotransferase (ALT) 55. Pancreatic enzymes and acute abdominal series were normal.The patient was admitted to the hospital with the presumptive diagnosis of viral gastroenteritis. Initial therapy included intravenous fluids and promethazine. Throughout hospital day 1, he remained nauseated and had multiple bouts of emesis. Records from the patient's hospitalization 5 months ago were obtained and reviewed. During this previous hospitalization, computed tomography (CT) scans of the abdomen and esophagogastroduodenoscopy (EGD) were performed, both of which were negative. Upon review of this recent workup, the diagnosis of cyclic vomiting syndrome (CVS) was entertained and the patient received a therapeutic trial of subcutaneous sumatriptan. His symptoms abated dramatically. Subsequently, he was able to keep oral liquids down and his orthostatic hypotension resolved. On hospital day 2, his white blood cell count normalized without intervention. Blood, urine, and stool cultures remained negative, and workup for acute intermittent porphyria was negative. Upon discharge from the hospital he was counseled to discontinue all marijuana use and was scheduled for follow-up in the residents' clinic. He failed to keep this appointment. After being lost to follow-up for 17 months, he presented to the emergency department with nausea and vomiting. As before, his symptoms promptly improved with sumatriptan. Discussion CVS, initially described in 1861 as a pediatric illness, is being increasingly recognized in adults. 1 It has been estimated that up to 1.6% of children experience symptoms consistent with this disorder, but the prevalence in adults is unknown. 2 The essential features of CVS, as noted in our patient, are multiple discrete episodes of nausea and vomiting lasting less than ...