Antipsychotic medicines are often prescribed ‘as required’ to manage behavioural and psychological symptoms of dementia, despite evidence that these medicines have little benefit for people with dementia and have numerous adverse side effects, including sedation. It is the nurse’s role to decide if and when to administer antipsychotic medicines that have been prescribed on an as required basis. This decision-making is underpinned by complex ethical considerations such as mental capacity, chemical restraint, quality of life and autonomy. Adopting a person-centred approach and considering the ethics, guidelines and legislation related to such decisions can support nurses to act in patients’ best interests. This article uses two ethical frameworks – the four principles of biomedical ethics and the ‘four quadrants’ approach – to examine this complex issue and to demonstrate their use in the context of ethical decision-making in nursing practice.