A sterile saline solution is made up of sterile water in which common salt, also known as sodium chloride, is dissolved. Sterile water is water that has been treated, commonly with high heat or chemicals, so that it contains no contaminants, such as bacteria, viruses, spores, and fungi, that can transmit infection or disease. Sodium chloride is also known by the chemical formula NaCl, and is the same kind of salt found in ocean water and cells of living organisms. Depending on what the sterile solution is used for, it can also contain additional ingredients such as glucose, dextrose, or various preservatives to keep it from becoming contaminated. Common uses for sterile saline solution include as an intravenous (IV) infusion for dehydrated patients, as a nasal rinse to treat congestion, to store soft contact lenses, and as a wound wash.
The most commonly used type of sterile saline solution contains 0.9% salt. This is the equivalent of 0.3 ounces (9 g) of salt being dissolved in 0.26 US gallons (1 liter) of water. This is very similar to the concentration of salt in human blood. A saline solution of this concentration is often used as an IV fluid to treat dehydration, for example in cases of severe diarrhea, and also after surgery. Saline solutions given intravenously often contain some type of sugar, like glucose or dextrose, to help maintain the proper chemical balance in the body.
Using a saline solution is often recommended for soft contact lens wearers who are allergic or sensitive to preservatives. It can also be used as a nasal rinse to relieve the symptoms of nasal congestion due to allergies, as well as viral or bacterial infection. There is no serious side effect associated with extended use of saline solution for nasal congestion, making it an alternative to many types of medications. A sterile solution can also be used to clean wounds and body piercings.
A sterile saline solution can easily become contaminated if it is exposed to the air, or objects that have not been subjected to sterilization. Some sterile solutions contain preservatives, or are sold in spray cans, to prevent contamination. A sterile saline solution can be made at home using table salt and boiled tap water. It is important to use sterile equipment, including sterile containers and utensils, for the saline solution to be completely sterile.