Comparative, cross-sectional study of the format, content and timing of medication safety letters issued in Canada, the USA and the UK.

Significant discrepancies in both the subject and timing of medication safety letters issued by health authorities in three countries (Canada, the USA and the UK) where medical practice is otherwise comparable, raising questions about why, how and when medication problems are identified and communicated to healthcare providers by the authorities. More rapid communication of medication problems and better alignment between authorities could enhance patient safety.