Polypharmacy is the concomitant prescribing of multiple medicines usually 5 or more. It is an important and preventable risk factor for adverse drug reaction with a huge cost burden in terms of related hospital admissions as well as patient morbidity and mortality. Whilst polypharmacy may improve symptom and disease management, it increases the risk of adverse drug reactions, drug-drug and drug-disease interactions, non-adherence and poor adherence to drugs, risk of the prescribing cascade, adverse health outcomes, increased mortality in frail older adults, increased health service use and costs.