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Getting the latest healthcare news for you

Patients with ulcerative colitis (UC) who develop acute intolerance syndrome (AIS) to 5-ASA medications — experiencing fever, abdominal pain, and bloody stool shortly after starting treatment — are significantly more likely to progress to difficult-to-treat disease. A retrospective study of 919 UC patients found that AIS, not 5-ASA intolerance broadly, is the key driver of this risk, suggesting it may represent a distinct, treatment-refractory UC subgroup.
Among patients with ulcerative colitis (UC), those who develop acute intolerance syndrome (AIS) to 5-aminosalicylic acid (5-ASA) medications face a significantly higher risk of progressing to difficult-to-treat (D2T) disease — defined as failure of at least two advanced therapies with different mechanisms of action. A retrospective cohort study of 919 UC patients published in the Journal of Gastroenterology found that while 5-ASA intolerance broadly was associated with D2T progression, AIS was the primary driver of that risk.
Researchers also found that earlier therapeutic escalation — prompted by intolerance — appeared to account for much of the increased D2T risk. Notably, among patients who continued using 5-ASAs at 90 days despite intolerance, D2T progression was less likely, suggesting that not all intolerant patients need to abandon the drug class immediately.
Key Takeaways:
Why it matters: Identifying AIS as a specific high-risk phenotype — rather than grouping all 5-ASA intolerance together — could help clinicians better stratify UC patients and make more informed, timely decisions about escalating to advanced therapies.