[Extract] Medical excess threatens the health of individuals and the sustainability of health systems. Unnecessary tests, treatments, and diagnoses bring direct harm to people through adverse effects of interventions, psychosocial impacts of labelling, and overwhelming burden of treatment. Overuse and overdiagnosis also consumes scarce resources, leading to underuse and underdiagnosis in other areas, which indirectly harms patients. As healthcare spending grows all over the world, with poor correlation between increased costs and improved health in high‐income countries, there is growing recognition that much of that spending is unnecessary. Increased costs of healthcare also draws resources from other societal sectors capable of improving health and wellbeing for the population. By tackling the crisis of medical excess, we can reduce harm and prevent waste, making our health systems more sustainable and more beneficial for patients and societies.