Purpose: Delirium is common with serious short- and long-term sequelae. However, there are no licensed treatments internationally and relatively little biomedical discovery with the target of finding a cure, with the invisibility or underestimation of the economic implications as a potential driver for this inertia. Methods: We conducted a narrative review of published literature in English quantitatively evaluating the financial and social costs of delirium to the health and care systems, patients and their carers. Results: Delirium increases the cost of the index hospitalisation as well as increasing the need for post-acute care and the demands on unpaid, often older, carers. Delirium may cause as much as 10% of all cases of dementia and the ongoing need for care of these people with dementia doubles the cost of delirium. Prevention of delirium not only reduces the cost of delirium but also may decrease subsequent rate of dementia. Conclusion: The high cost of delirium itself as well as the resultant dementia warrants greater efforts to prevent delirium and discover effective treatment.