This guideline covers the general principles for managing intravenous (IV) fluid therapy in hospital inpatients aged 16 and over with a range of conditions. It aims to help prescribers understand the optimal amount and composition of IV fluids to be administered and the best rate at which to give them, to improve fluid prescribing and outcomes among people in hospital. It does not cover pregnant women, and those with severe liver or renal disease, diabetes or burns.