Ischemic colitis induced by indigo naturalis in a patient with ulcerative colitis: a case report

BACKGROUND: Indigo naturalis is a Chinese herbal medicine that has currently been used to treat various inflammatory diseases, including ulcerative colitis. Recently, there are several reports concerning severe adverse events associated with indigo naturalis. CASE PRESENTATION: We described a case of a 44-year-old female with ulcerative colitis who presented with lower abdominal pain and hematochezia. She stopped taking her medicine for ulcerative colitis and started oral indigo naturalis 3 months before admission. Computed tomography showed segmental edematous wall thickening of the descending and sigmoid colon. Colonoscopy findings revealed erythema, edema, and submucosal hemorrhage, the surface of which presented a dark blue pigmentation. The histologic finding was consistent with ischemic colitis. We therefore considered an ischemic colitis induced by indigo naturalis, and the patient improved after supportive care and withdrawal of indigo naturalis. CONCLUSION: Indigo naturalis has currently been used in the patients with ulcerative colitis as an alternative therapy. However, physicians should be aware of possible severe adverse events such as ischemic colitis.