OBJECTIVES: Product labeling conveys information about the potential risks of medication for healthcare professionals and consumers, but the consistency (or inconsistency) of such information is unknown.  We sought to investigate the consistency of information intended for healthcare professionals versus consumers about cardiovascular risks from stimulants approved in four English-speaking countries. METHODS: Professional and consumer drug product labels were obtained in July 2014 from regulatory agencies in Australia, Canada, United Kingdom, and United States.  Language describing the nature of the relationship between the drug and four major cardiovascular adverse events (elevated blood pressure and/or heart rate, stroke, myocardial infarction, and sudden death) was extracted verbatim and classified into one of four mutually exclusive categories: confirmed, unconfirmed, mixed and not mentioned. RESULTS: We obtained professional and consumer product labeling for 24 unique, approved stimulants (16 US, 6 UK, 6 Canada, and 5 Australia). Language regarding the relationship between drug and cardiovascular adverse events was consistent for professional and consumer audiences 54.5% of the time (59% US, 20% Australia, 58% Canada, 67% UK).  One in three (32%) labels for professionals and consumers included inconsistent language that described a drug-adverse event relationship as both confirmed and unconfirmed. CONCLUSIONS: Regulator approved product labeling provides healthcare professionals and consumers with inconsistent messages regarding the certainty (or uncertainty) of the relationship between stimulant use and specific cardiovascular risks in children and adolescents. Professionals and consumers often receive “mixed” messages about the actual risk of a particular cardiovascular event within the same label.  The implications towards patient safety and outcomes warrants further study.