Saline, also known as saline solution, is a mixture of sodium chloride and water. It is used to clean wounds and remove foreign objects, such as dirt, from the eye. Saline solution is also used in contact lenses and eyeglasses.
The human body is about 60% water, give or take. In a healthy person, most of that water is inside cells where it helps them function properly. The rest is extracellular fluid, which includes blood plasma and interstitial fluid between cells. Saline solutions are isotonic with respect to human blood; they have the same concentration of solutes as plasma (0.9%). This means that they can be used to intravenously infuse fluids into the bloodstream without disturbing the body’s fluid balance.
One liter of 0.9% saline solution contains 9 g of sodium chloride (NaCl). The solution has a slightly salty taste but does not contain enough salt to be harmful if ingested in small amounts.
Saline solutions are commonly used in medicine because they are safe and easy to administer IVs with. They are also useful for irrigating wounds and cleaning out debris before applying bandages or stitches. Additionally, sterile saline solutions can be used as contact lens cleaners and rinses for those who wear contacts regularly.