Medication-associated lesions of the GI tract.

At a Harben Lecture in London in 1908, German scientist Paul Ehrlich described the ideal drug as a “magic bullet” (Zauberkugel). Such a drug would be aimed precisely at a disease site and would not affect healthy tissues. Today, over 3.5 billion prescriptions are dispensed each year in the United States to manage a broad number of health disorders. Although many drugs are aimed more accurately than their predecessors, none of them, as of yet, hit their targets exclusively. Several medications are associated with an increasing incidence of drug-induced (iatrogenic) adverse events, a frequent site of which is the GI tract. In fact, 10% of the drug-induced adverse effects are related to the GI tract. The consequences of such can range from asymptomatic histologic changes in the GI mucosa to fatal adverse events. In some instances, the adverse events are worse than the illness for which the drug was prescribed. However, many drug-induced adverse events are preventable. Therefore, it is becoming increasingly important to recognize both the clinical and pathologic manifestations of GI tract drug-induced injury early, so that the offending drug can be discontinued or replaced. This review uses an organ-based approach to present both clinical information and pathologic findings to increase clinical awareness of the most common druginduced GI conditions. Although each part of the GI tract has been considered separately, some drugs exert a