Ischemic Colitis Following Baloxavir Marboxil Administration.

A woman in her 60s developed abdominal pain, diarrhea, and hematochezia two days after taking a single 40 mg dose of baloxavir marboxil for influenza A. Colonoscopy on day 10 revealed mucosal edema and longitudinal ulcerations confined to the sigmoid colon. A histopathological examination showed neutrophilic infiltration, crypt epithelial detachment, degeneration, and atrophy, consistent with ischemic colitis. Stool cultures were negative. The patient was managed conservatively with probiotics and her symptoms gradually improved. This case highlights the importance of considering ischemic colitis as a potentially adverse event associated with baloxavir marboxil.