The US Food and Drug Administration approved a revised package insert for two cancer drugs to include information about the increased risk of severe adverse events owing to enzyme deficiencies caused by genetic variants. The label revisions stopped short of recommending or requiring pharmacogenetic testing prior to or following an adverse event. Despite (or because of) the lack of specific recommendations, we believe the actions taken by US Food and Drug Administration will have implications for pharmacogenetics research, clinical integration, and other policy considerations. We review the reasons behind the cautious label changes and discuss some of the lessons that can be learned from these experiences.