Classification and clinical features of adverse drug reactions in patients with ulcerative colitis treated with 5‐aminosalicylate acid: a single-center, observational study

Background 5-Aminosalicylate acid (5-ASA) is a crucial drug for ulcerative colitis (UC) patients. 5-ASA has several side effects. However, the types of side effects vary and are sometimes severe.Methods A single-center, retrospective cohort study was conducted from September 2001 to June 2020. We surveyed consecutive UC patients who visited our hospital and investigated adverse drug reactions (ADRs) related to 5-ASA formulations. We grouped patients into four subgroups: (1) lupus-like symptoms, (2) blood test abnormalities, (3) mimicking IBD exacerbation and (4) others. Their clinical courses were evaluated.Results We surveyed 288 consecutive UC patients, 35 of whom developed ADRs of any grade (12.9%), and analyzed 27 patients. The median age and 5-ASA doses were 43 years and 4000 mg, respectively, and 48% were male. The ADR triggers were the first use of 5-ASA (n = 17, 63%), 5-ASA switch (n = 9, 33%) and 5-ASA dose escalation (n = 1, 3.7%). The median time to ADR was 15 days (IQR: 7, 63). Ten patients (37%) had grade 3/4 ADRs. Fever was the most common ADR (n = 6, 23%), followed by hyperamylasemia and headache (n = 4, 15%). Lupus-like symptoms accounted for 56% (n = 15), blood test abnormalities for 26% (n = 7), mimicking IBD exacerbation for 15% (n = 4) and others for 3.7% (n = 1). The time to ADR was shorter in the mimicking IBD exacerbation group (median 11 days) than in the lupus-like symptoms (22 days) and blood test abnormalities (55 days) groups.Conclusion Classification of ADRs related to 5-ASA into four groups might lead to early recognition of ADRs.