Indigo naturalis‑associated ischemic injury of colorectal mucosa: A case series study

Indigo naturalis, a traditional Chinese herbal medicine characterized by its dark blue hue, is utilized in the treatment of a diverse array of diseases, including ulcerative colitis, psoriasis, oral ulcers, radiation proctitis, chronic myelocytic leukemia and herpes zoster. The common adverse effects associated with indigo naturalis include liver dysfunction, headaches, abdominal pain and nausea. Notably, case reports have documented instances of ischemic injury to the colorectal mucosa attributed to indigo naturalis. The present case series study aimed to elucidate the clinical characteristics of patients that experienced an ischemic injury of the colorectal mucosa due to consuming Chinese patent medicines containing indigo naturalis. The present study included 15 patients (mean age, 61.7±15.1 years; 5 male patients) that were admitted to the Second Affiliated Hospital of Jiaxing University (Jiaxing, China) between March 2013 and February 2016. The patients developed ischemic colonic mucosal injuries after consuming indigo naturalis through Chinese patent medicines, with an incidence rate of 1.3% (15/1,157 patients). Overall, 9/15 patients had idiopathic thrombocytopenic purpura and 6 patients had schistosomal liver fibrosis with hypersplenism but normal myeloproliferative thrombocytopenia. The duration of continuous treatment with indigo naturalis-containing Chinese patent medicines ranged from 12-330 days, with a mean of 98.0±52.3 days. Gastrointestinal symptoms, including abdominal pain, diarrhea and hematochezia, were observed 6-90 days after starting the indigo naturalis-containing Chinese patent medicines, with a mean onset of 28.9±22.2 days. Abdominal computed tomography scans and colonoscopy revealed lesions predominantly in the right hemi-colon and the entire colon, including the rectum. Gastrointestinal symptoms resolved 17.3±12.4 days after discontinuing the treatment with indigo naturalis-containing Chinese patent medicines, and patients had a favorable prognosis and did not experience a recurrence of ischemic colitis. Therefore, individuals taking indigo naturalis orally may be susceptible to developing ischemic injuries of the colorectal mucosa. In cases where colonoscopy indicates a suspected mucosal ischemic injury, it is suggested that endoscopists inquire about the medical history of the patient in order to establish a definitive diagnosis and adjust the dose of the indigo naturalis-containing drug to mitigate the adverse effects.