Dehydration is common among older adults. A narrative literature review was conducted to determine the current state of knowledge regarding the symptoms, prevention, and early treatment of dehydration. Fifty-three full-text articles from the years 2015–2025 were selected for the final analysis. The most common cause of dehydration in older people is insufficient fluid intake. Dehydration can also be a symptom of diseases common in older adults, including urinary tract infections, pneumonia and other febrile illnesses, as well as diabetes. In addition to medical causes, dehydration can result from a lack of knowledge regarding the importance of adequate fluid intake, lifestyle habits, and economic factors. Dehydration is primarily diagnosed through a medical interview and physical examination. Objective methods of diagnosis include serum osmolality, the serum urea-to-creatinine ratio, serum sodium concentration, haematocrit, urine specific gravity, and methods utilising bioimpedance, as well as devices such as smartwatches or wristbands. Consequences of dehydration can include delirium, renal failure, and cardiovascular diseases (stroke, transient ischaemic attack, myocardial infarction, and thrombosis etc.). The most important element of a dehydration prevention strategy is educating patients and their caregivers about the importance of proper hydration, early recognition and treatment of dehydration. Med Pr Work Health Saf. 2026;77(4)