S6063 A Gut Reaction: Duodenal Vasculitis Unveiled After Mounjaro Use

Introduction: Tirzepatide and other glucagon-like peptide-1 receptor agonists are widely used to treat type 2 diabetes and obesity; however, their potential effects on drug metabolism and immune regulation remain important areas of ongoing investigation. They have been linked to immune-related side effects, including hypersensitivity reactions, hives, and bullous pemphigoid. Other reported effects include facial fat loss commonly referred to as ‘Ozempic face’ and hair thinning. There are only a limited number of published reports documenting vasculitis associated with tirzepatide. Case Description/Methods: A 63-year-old man with type 2 diabetes, hypertension, and obesity presented with 2 weeks of non-radiating abdominal pain, nausea, loose stools, and decreased appetite, beginning after his tirzepatide dose was increased to 7.5 mg. Vitals were stable; exam showed mild diffuse abdominal tenderness. Labs revealed leukocytosis (WBC 15.2), normal renal and liver function, lipase 77, and negative infectious and inflammatory bowel disease workup. Computed tomography imaging including enterography showed duodenitis and proximal jejunitis. Endoscopy showed erosive esophagitis and duodenal inflammation; biopsy revealed duodenal vasculitis with no evidence of infection. He was treated with intravenous steroids (solumedrol 40 mg three times a day), with symptom improvement, and discharged on an oral steroid taper. Outpatient rheumatologic evaluation ruled out systemic autoimmune vasculitis, confirming drug-induced vasculitis likely due to tirzepatide. Discussion: Medication-induced vasculitis involving the gastrointestinal (GI) tract is a severe condition in which drug-related inflammation of blood vessels results in injury to the digestive organs. This condition generally arises within a few weeks of beginning a new drug and tends to resolve once the medication is stopped. As GLP-1 receptor agonists become more commonly used for weight management, clinicians should remain vigilant for potential side effects. Upcoming prospective research, along with ongoing adverse event monitoring and post-marketing data collection, will play a vital role to better understand the immunomodulatory properties of tirzepatide and if vasculitis occurs more frequently as a side effect than is presently understood.