Creighton University School of Medicine Phoenix, AZ
Dillon Cardinale, BS1, Ericka Charley, MD1, Vikash Kumar, MD1, Amla Patel, MBBS2, Aida Rezaie, MD1, Shahab Aftahi, MD, BS1 1Creighton University School of Medicine, Phoenix, AZ; 2Creighton University, Phoenix, Phoenix, AZ Introduction: Mesalamine (5-ASA) is a first-line treatment for mild ulcerative colitis (UC), but hypersensitivity reactions occur in up to 11% of patients, with increasing reports since 2007. These reactions often mimic UC flares, presenting with symptoms such as fever, worsening diarrhea, hematochezia, chest pain, palpitations, and arthralgia. We report a case of mesalamine-induced hypersensitivity initially mistaken for recurrent UC flare and C. difficile colitis.
Case Description/
Methods: A 27-year-old female was initially diagnosed with suspected UC vs. Crohn’s disease at an outside facility and started on prednisone and mesalamine. She presented to the ED with severe bloody stools, chest pain, palpitations, flushing, weakness, and a ground-level fall. She had recently tested positive for C. difficile, untreated. On arrival, she was hypotensive and transferred to the ICU for suspected hypovolemic or septic shock. CTA showed colitis; troponin was elevated to 1.072 ng/mL, fecal calprotectin was 1609, and ECG showed no ischemic changes. Colonoscopy revealed pancolitis with Mayo 3 severity; EGD was normal. She was treated with oral vancomycin and IV steroids for presumed severe C. difficile colitis on UC flare. She improved, transitioned to oral prednisone, and restarted mesalamine 4.8 g daily with plans for outpatient Anti-TNF therapy.
Two days post-discharge, she returned with recurrent bloody diarrhea, weakness, and chest pain, requiring ICU admission for pressor support. Troponin remained intermittently elevated (0.055–1.027 ng/mL); repeat ECG, echocardiogram, cardiac MRI, and chest CTA were unremarkable. Given her symptoms, troponin elevation, flushing, and timing, mesalamine hypersensitivity was suspected rather than myocarditis or pericarditis, both ruled out.
Mesalamine was discontinued, prednisone tapered, and infliximab initiated (10 mg/kg) due to low albumin and elevated CRP. At two months, she was clinically well, fecal calprotectin normalized, and remained on infliximab maintenance. Discussion: Mesalamine hypersensitivity should be suspected in patients with worsening symptoms soon after therapy initiation, especially when chest pain and troponin elevation occur without evidence of cardiac disease. Recognizing this reaction early is crucial to avoid unnecessary treatments for presumed UC flare or cardiac conditions. Discontinuation of mesalamine leads to symptom resolution and allows initiation of appropriate therapy.
Disclosures: Dillon Cardinale indicated no relevant financial relationships. Ericka Charley indicated no relevant financial relationships. Vikash Kumar indicated no relevant financial relationships. Amla Patel indicated no relevant financial relationships. Aida Rezaie indicated no relevant financial relationships. Shahab Aftahi indicated no relevant financial relationships.
Dillon Cardinale, BS1, Ericka Charley, MD1, Vikash Kumar, MD1, Amla Patel, MBBS2, Aida Rezaie, MD1, Shahab Aftahi, MD, BS1. P3376 - Flare, Infection, or Hypersensitivity? Recognizing Mesalamine Hypersensitivity in Ulcerative Colitis With <i>C. difficile</i>, ACG 2025 Annual Scientific Meeting Abstracts. Phoenix, AZ: American College of Gastroenterology.
