Review article: drug-induced microscopic colitis - proposal for a scoring system and review of the literature.

The pathophysiology of microscopic colitis is unknown, although it is thought to be because of an abnormal immune reaction to luminal antigens in predisposed hosts. Specific antigens have not been proved, although various infectious triggers and drugs have been proposed. The responsibility of several drugs has been questioned, some with strong clinical and/or histological evidence suggesting causality. The issue of drug-induced microscopic colitis is important because of the burden of this disease. Thus, any case that can be cured by withdrawal of a drug must be identified. In this report, we propose a scoring system for drug-induced microscopic colitis, adapting existing criteria of drug causality, and review the literature using this framework. Based on this review, several drugs are identified with intermediate or high likelihood of inducing microscopic colitis. Finally, we suggest how to treat individual patients suspected of having drug-induced colitis according to the level of evidence for that particular drug.