Intravenous fluid therapy is ubiquitous in modern medicine. The range of fluids available for intravenous administration represents a major advance from the early days of intravenous fluids in the 1830s, which began in the midst of the cholera epidemic in London, England. Latta is credited with treating the first patients with intravenous fluids consisting of “two drachms of muriate, and two scruples of carbonate, of soda, to sixty ounces of water” (or 106 mmol/L of Na+, 78 mmol/L of Cl−, and 15 mmol/L of CO32−).1,2 Today, physicians can choose from a large menu of intravenous fluid replacement products: hypotonic, isotonic, and hypertonic crystalloids of varying compositions; synthetic colloids (gelatins, hydroxyethyl starches, dextrans); and human-derived colloids (albumin, fresh-frozen plasma, and red blood cells). The choice depends on the clinical context, physiological considerations, and geographic, institutional, or subspecialty custom.3