Nat Rev Neurol 18 (10): 579 - 596, 2022. doi: 10.1038 / s41582 - 022 - 00698 - 7 Etiology of Delirium The most common causes of delirium are the following: Drugs, particularly anticholinergics, psychoactive drugs or medications, and opioids Dehydration Infection Many other conditions can cause delirium (see table).