Summary Delirium is described in the DSM-5 as an acute fluctuating syndrome characterised by a change in consciousness, perception, orientation, cognition, sleep–wake rhythm, psychomotor skills, and the mood and feelings of a patient. The delirium prevalence varies among hospital patient populations ranging from 5% for elective orthopaedic surgery to 87% for intensive care unit (ICU) patients. The causes of delirium vary, but there is almost always a somatic cause, putting frail and cognitively impaired patient and patients with multimorbidity at the highest risk of delirium. Patients with delirium often have a risk of morbidity, mortality, prolonged hospital length of stay, high rates of institutionalization, and cognitive decline. Delirium is also associated with long-term cognitive decline. Delirium increases the cost of the index hospitalization as well as the need for post-acute care and the demands on unpaid, often older caregivers. Delirium and delirium prevention continue to be a challenge for healthcare professionals, especially for nurses who form the basis of patient care. It also causes distress for patients, their caregivers, and healthcare professionals. In 30–40% of cases, delirium is a preventable condition. Prevention starts by patients at risk of delirium being identified using a delirium risk model, followed by management of these patients using delirium screening tools and non-pharmacological preventive interventions. Twenty-eight delirium risk models have been developed for several populations with different variables to score. Most models use lab values and cognitive tests and require trained personnel and time to score. The Delirium Risk Assessment Score (DRAS) is a model which is easy to score, needs no training and extra tests. It is based on the predisposing risk factors for delirium which can be found in a nursing admission interview. The DRAS is validated in different patient populations including a surgical and a covid patient population. Several delirium screening and severity scales for hospital inpatients are described in different review articles. The delirium screening scales are developed for doctors, nurses, psychologists or psychiatrists. The scales can be divided into screening scales for the detection of delirium and severity scales for measuring the severity of delirium. In total, 21 delirium screening scales were found and 9 severity scales which can be used in hospitals. The first screening scale was published in 1992 and the first severity scale in 1994. Many of the scales mentioned have not been implemented into daily practice or outside the centres where they were developed. Furthermore, it is noted that most scales are only used in research regarding delirium in specific patient populations. The exceptions are the CAM, CAM-ICU, DOSS, NEECHAM, DRSR-98, MDAS, and the 4AT. Non-pharmacological treatment for the prevention of delirium involves providing an unambiguous, supportive environment to improve the orientation and maintain the competence of the patients. The components of non-pharmacological prevention can be divided into providing support and orientation, providing an unambiguous environment, measures at maintaining competence, and providing other supportive measures. Several non-pharmacological interventions consist of an orientation plan, therapeutic activities, sleep enhancement, (early) mobilization, a vision and/or hearing protocol, encouraging fluid intake, feeding assistance, family involvement, or an individual care plan. Delirium prevention increases patient well-being, as well as decreasing staff workload and reducing costs. And a successful implementation of prevention of delirium in daily practice starts with knowledge and the attitude of nurses and doctors. Nevertheless, several studies reveal a shortfall in nurses´ knowledge of delirium prevention, which has a negative impact on the number of appropriate outcomes. In addition, despite the fact that the knowledge from research on delirium detection, control and prevention is available, its application in daily practice can still be improved.