(1) Objective: We performed a systematic review to explore the prevalence of intravenous (IV)
rehydration therapy in hospital settings, and we assessed it by patient groups and populations. (2) Methods: A systematic review of major databases and grey literature was undertaken from inception to 28 March 2022. Studies reporting prevalence of IV
rehydration therapy in a hospital setting were identified. The data were synthesised in a narrative approach. (3) Results: Overall, 29 papers met the inclusion criteria. The prevalence of IV
rehydration therapy in paediatric patients ranged from 4.5% (hospitalised with diarrhoea and
dehydration) to 100% (admitted to the emergency department with mild to moderate
dehydration caused by viral
gastroenteritis), and in adults this ranged from 1.5% (had single substance ingestion of
modafinil) to 100% (hospitalised with
hypercalcemia). The most common indication for IV
rehydration therapy in paediatric patients was
dehydration due to fluid loss from the gastrointestinal tract. Other causes included
malnutrition,
neuromuscular disease,
bronchiolitis, and
influenza. In adults, indications for IV
rehydration therapy were much more diverse:
fever, diarrhoea,
drug intoxication,
hypercalcemia,
cancer, and
postural tachycardia syndrome; (4) Conclusions: This systematic review showed that IV
rehydration therapy in paediatric patients is often used to treat
dehydration and diarrhoea, while in adults it has a broader spectrum of use. While IV
rehydration therapy is important in correcting fluid problems and
electrolyte status, the maintenance fluid prescribing practices vary considerably, and guidelines are scarce.