The United States Pharmacopeia (USP) drug substance monograph for Heparin Sodium, and drug product monographs for Heparin Lock Flush Solution and Heparin Sodium Injection, recently have undergone several revisions following serious and fatal events related to the use of heparin sodium products. Investigation of heparin product overdose errors identified the expression of drug strength in the labels as a major contributing factor in these errors. This guidance document addresses these safety concerns by clarifying new expectations for labeling with regard to the revised heparin USP monographs, as well as outlining safety testing recommendations.