Background Prescription medication borrowing and sharing is a behaviour that has been identified in patients of all ages. This behaviour is recognised by medical researchers and government health authorities as a potential risk factor in adverse drug events across the community. Objective This article discusses prescription medication borrowing and sharing and identifies populations more likely to participate in this behaviour. It also focuses on the classes of drugs identified in the research literature as those being more likely to be borrowed or shared. Discussion Prescription medication borrowing and sharing behaviours have been associated with several risk factors such as polypharmacy and multiple chronic comorbidities. General practitioners and health professionals are therefore encouraged to counsel patients, at the time of issuing prescriptions and following discharge from hospital, on the risks of borrowing and sharing prescription medications and the safe disposal of ‘left over’ prescription medications.