This guideline contains recommendations about general principles for managing intravenous (IV) fluids, and applies to a range of conditions and different settings. It does not include recommendations relating to specific conditions. Many adult hospital inpatients need intravenous (IV) fluid therapy to prevent or correct problems with their fluid and/or electrolyte status. Deciding on the optimal amount and composition of IV fluids to be administered and the best rate at which to give them can be a difficult and complex task, and decisions must be based on careful assessment of the patient’s individual needs. Errors in prescribing IV fluids and electrolytes are particularly likely in emergency departments, acute admission units, and general medical and surgical wards rather than in operating theatres and critical care units. Surveys have shown that many staff who prescribe IV fluids know neither the likely fluid and electrolyte needs of individual patients, nor the specific composition of the many choices of IV fluids available to them. Standards of recording and monitoring IV fluid and electrolyte therapy may also be poor in these settings. IV fluid management in hospital is often delegated to the most junior medical staff who frequently lack the relevant experience and may have received little or no specific training on the subject. The National Confidential Enquiry into Perioperative Deaths report in 1999 highlighted that a significant number of hospitalised patients were dying as a result of infusion of too much or too little fluid. The report recommended that fluid prescribing should be given the same status as drug prescribing. Although mismanagement of fluid therapy is rarely reported as being responsible for patient harm, it is likely that as many as 1 in 5 patients on IV fluids and electrolytes suffer complications or morbidity due to their inappropriate administration. There is also considerable debate about the best IV fluids to use (particularly for more seriously ill or injured patients), resulting in wide variation in clinical practice. Many reasons underlie the ongoing debate, but most revolve around difficulties in interpretation of both trial evidence and clinical experience, including the following factors: Many accepted practices of IV fluid prescribing were developed for historical reasons rather than through clinical trials. Trials cannot easily be included in meta-analyses because they examine varied outcome measures in heterogeneous groups, comparing not only different types of fluid with different electrolyte content, but also different volumes and rates of administration and, in some cases, the additional use of inotropes or vasopressors. Most trials have been undertaken in operating theatres and critical care units rather than admission units or general and elderly care settings. Trials claiming to examine best early therapy for fluid resuscitation have actually evaluated therapy choices made after initial fluid resuscitation, with patients already in critical care or operating theatres. Many trials inferring best therapy for fluid resuscitation after acute fluid loss have actually examined situations of hypovolaemia induced by anaesthesia. There is a clear need for guidance on IV fluid therapy for general areas of hospital practice, covering both the prescription and monitoring of IV fluid and electrolyte therapy, and the training and educational needs of all hospital staff involved in IV fluid management. The aim of this NICE guideline is to help prescribers understand the: physiological principles that underpin fluid prescribing; pathophysiological changes that affect fluid balance in disease states; indications for IV fluid therapy; reasons for the choice of the various fluids available principles of assessing fluid balance. In developing the guideline, it was necessary to limit the scope by excluding patient groups with more specialised fluid prescribing needs. It is important to emphasise that the recommendations do not apply to patients under 16 years, pregnant women, and those with severe liver or renal disease, diabetes or burns. They also do not apply to patients needing inotropes and those on intensive monitoring, and so they have less relevance to intensive care settings and patients during surgical anaesthesia. Patients with traumatic brain injury (including patients needing neurosurgery) are also excluded. The scope of the guideline does not cover the practical aspects of administration (as opposed to the prescription) of IV fluids. It is hoped that this guideline will lead to better fluid prescribing in hospitalised patients, reduce morbidity and mortality, and lead to better patient outcomes. Strategies for further research into the subject have also been proposed. The guideline will assume that prescribers will use a drug’s summary of product characteristics to inform decisions made with individual patients.