Acute Severe Pancolitis After Initiation of a Calcitonin Gene-Related Peptide Receptor Antagonist: A Case Report.

Calcitonin gene-related peptide receptor antagonists (CGRP-RA) are increasingly prescribed for migraine prophylaxis. Gastrointestinal side effects have been described, but association with inflammatory bowel disease (IBD) is reported rarely. A 50-year-old woman with well-controlled ulcerative proctitis developed a severe flare shortly after commencing a CGRP-RA (atogepant). She presented with abdominal pain and diarrhea. Investigations showed elevated inflammatory markers, predominantly right sided colitis on computer tomography scan, as well as endoscopic and histological evidence of severe pancolitis. Treatment with intravenous steroids was ineffective, but she responded to infliximab and discontinuation of the CGRP antagonist. She was well at follow-up 3 months later. CGRP-RA may can be associated with IBD relapse or de novo disease. We present a case of acute flare with change in phenotype of disease. Clinicians should exercise caution when prescribing CGRP-RA in patients with known IBD.