Normal saline (NS or N/S) is the commonly used phrase for a solution of 0.90% w/v of NaCl, about 300 mOsm/L or 9.0 g per liter.
Less commonly, this solution is referred to as physiological saline or isotonic saline, neither of which is technically accurate. Normal saline was invented by Dutch physiologist Hartog Hamburger in 1896. It is used frequently in intravenous drips (IVs) for patients who cannot take fluids orally and have developed or are in danger of developing dehydration or hypovolemia. NS is also used for aseptic purpose. NS is typically the first fluid used when hypovolemia is severe enough to threaten the adequacy of blood circulation, and has long been believed to be the safest fluid to give quickly in large volumes. However, it is now known that rapid infusion of NS can cause metabolic acidosis.
