Drug-induced pathology in the large intestine

Many drugs can cause pathology in the large intestine. Major classes include antibiotics, non-steroidal anti-inflammatory drugs, laxatives, anticancer drugs and immunosuppressive agents. The pathogenesis of the lesions caused by drugs is highly variable. Toxic injury and vascular insufficiency are probably the most important mechanisms. The microscopic pattern of such lesions is generally non-specific. They may produce histological patterns that resemble acute infectious-type colitis, microscopic colitis, ischaemic colitis and even chronic idiopathic inflammatory bowel disease. Specific features, such as the presence of crystals (Kayexalate), pigment and diaphragms, indicating a specific diagnosis are less common. The precise incidence of drug-induced damage to the large intestine is not known, but the importance of the phenomenon is probably underestimated. A correct histopathological diagnosis is difficult and requires a careful clinical history and the consideration of the possibility of a drug-related aetiology.