5-Aminosalicylic acid (5-ASA) has structural similarities to both phen
acetin and aspirin, which are known to cause 'analgesic nephropathy'.
Because of the increasing use of 5-ASA, this paper draws attention to
two cases of severe interstitial nephritis resulting from 5-ASA and em
phasises the importance of monitoring renal functions of patients with
inflammatory bowel disease who are receiving 5-ASA preparations.