A 58-year-old man with bilateral knee osteoarthritis presented to the emergency department with 1 week of dizziness and intermittent dark stools. He denied dyspnea on exertion, angina, history of liver disease, or recent dietary or medication changes. Home medications included as-needed ibuprofen. On physical examination, he was afebrile, blood pressure was 100/65, and heart rate 98 beats per minute. Abdominal examination disclosed a soft, nontender, nondistended abdomen with normal bowel sounds. Digital rectal examination (DRE) revealed black, tarry, foul-smelling stool but no fresh or frank blood. Fecal occult blood testing (gFOBT) was performed reflexively after rectal examination and returned negative results. Laboratory testing results revealed hemoglobin 11.0 mg/dL (baseline, 13.6 mg/dL 3 months previously; to convert to g/dL, multiply by 10.0), platelets 278 000 mm 3 , blood urea nitrogen of 28 mg/dL (to convert to mmol/L, multiply by 0.357), serum creatinine of 0.98 mg/dL (to convert to μmol/L, multiply by 76.25), and normal coagulation parameters. He was admitted to the hospital but a gastroenterology consultation was initially deferred given the negative results from the FOBT. The admitting clinicians consulted gastroenterology 7 hours later when the patient again had a black tarry bowel movement. The patient was subsequently given intravenous pantoprazole, and upper endoscopic findings revealed three 1.5-cm duodenal ulcers, 1 of which had a visible vessel, which was treated with epinephrine injection and hemostatic clips. The ulcers were attributed to ibuprofen use. The patient was given oral pantoprazole on discharge to be taken for 2 months or as long as he continued to use ibuprofen. He had no recurrence of GI tract bleeding at 9 months' follow-up.