Clinical decision support systems--interactive computer systems that help doctors make clinical choices--can reduce errors in drug prescribing by offering real-time alerts about possible adverse reactions. But physicians and other users often suffer "alert fatigue" caused by excessive numbers of warnings about items such as potentially dangerous drug interactions. As a result, they may pay less attention to or even ignore some vital alerts, thus limiting these systems' effectiveness. Designers and vendors sharply limit the ability to modify alert systems because they fear being exposed to liability if they permit removal of a warning that could have prevented a harmful prescribing error. Our analysis of product liability principles and existing research into the use of clinical decision support systems, however, finds that more finely tailored or parsimonious warnings could ease alert fatigue without imparting a high risk of litigation for vendors, purchasers, and users. Even so, to limit liability in this area, we recommend stronger government regulation of clinical decision support systems and development of international practice guidelines highlighting the most important warnings.