Intravenous fluids are routinely given to children when the enteral route is not sufficient or it’s not an option, such as during surgery and anaesthesia. Lack of understanding of the composition of fluids and the appropriate rate to administer them has been associated with serious morbidity and mortality in children. Recent evidence has shown that giving children isotonic fluids with a sodium concentration similar to plasma decreases the risk of hyponatraemia without an increase in adverse effects. This has led to a change in guidelines, which now recommend that isotonic fluids are used in children along with regular monitoring of fluid balance and electrolytes. Current evidence supported by several anaesthesia societies across the world recommend that children are allowed and should be encouraged to drink clear fluids up to one hour before elective surgery. Evidence is starting to emerge from enhanced recovery programmes in children of improved outcomes from individualised perioperative fluid therapy and avoidance of prolonged preoperative fasting. Strategies to reduce blood transfusion in children having surgery include treatment of preoperative iron deficiency, acceptance of low transfusion thresholds, cell salvage and tranexamic acid administration.