Healthy Aging Pharmacogenomics and Polypharmacy (HAPPY) Polypharmacy (taking multiple medications, often classified as 5 or more) is associated with increased adverse drug reactions and in the UK 2million 65+yrs are on at least 7 medications a week. Pharmacogenomics (PGx) looks at how an individuals genetic make-up affects their likely response to drugs. PGx-informed medication management in the over 65’s has been shown to reduce medical changes, however several barriers have been identified preventing widespread adoption of PGx, including lack of evidence in using PGx results, uncertainty in interpretation of results, lack of integration with electronic medical records and decision support tools. The HAPPY project is developing an innovative, scalable, integrated clinical decision support platform to support the implementation of PGx into primary care and developing an implementation plan for PGx in polypharmacy patients via a clinical study providing PGx reports to general practitioners.