Ischemic colitis (IC) is thought to occur more frequently in the elderly, but the incidence in young and middle-aged adults is increasing. This study determined the clinical characteristics of and risk factors for young and middle-aged IC patients. The medical records of 190 IC patients from 2010-2020 were reviewed. The clinical features of the young and middle-aged IC group (group A, < 60 years [n=70]) were compared to the elderly IC (group B, ≥60 years [n=120]) and age- and gender-matched colon polyp groups (group C, <60 years [n=272]). Independent risk factors for IC in group A were assessed using multivariate logistic regression analysis. There were no significant differences in groups A and B with respect to season of onset, symptoms, signs, treatment, or recurrences. The main symptoms of group A were abdominal pain (98.6%) and hematochezia (98.6%). Lesions commonly involved the left half of the colon (87.1%) and the clinical conditions were generally not severe. The percentage of patients with constipation (11.4% vs. 4.0%, P=0.034) and using a calcium channel antagonist (21.4% vs. 11.4%, P=0.028) was significantly higher in group A than group C. Regression analysis demonstrated that constipation (OR 2.831, P=0.037) and taking a calcium channel antagonist (OR 2.486, P=0.012) were closely associated with the occurrence of IC in group A. Constipation and taking a calcium channel antagonist were independent risk factors for the onset of IC in young and middle-aged adults. Among young and middle-aged adults with abdominal pain and bloody stools who also have constipation or are taking a calcium channel antagonist to treat hypertension, the diagnosis of IC should be considered.