Saline solution is a solution of sodium chloride, or salt, in sterile water. Normal saline solution is 0.9% sodium chloride, though this refers to only one possible concentration. Other concentrations may be used for different purposes. Normal saline is most commonly used as an intravenous (IV) infusion, administered through an IV drip for patients who have become severely dehydrated and to prevent dehydration in patients who cannot consume liquids and nutrients by mouth.

As an intravenous infusion, a saline solution is typically mixed with dextrose or glucose to reduce any complications from infusing saline solution and to reduce the amount of sodium circulating through the blood stream. This works particularly well as a water and nutrient supplement to sustain hospitalized patients who are unable to eat or drink or who have suffered dehydration from severe vomiting or diarrhea. Other medical purposes for saline solution include rinsing and safe storage of contact lenses, as well as nasal irrigation. Saline solution for rinsing and storing contact lenses may sometimes contain other chemicals for sterilization, and it is not recommended that contact lens solution be used for nasal irrigation without being certain it is a normal saline solution.

As a nasal irrigation, saline solution helps to safely rinse out the nasal cavity and promote nasal health. People who suffer from chronic sinus problems, including congestion and nasal irritation, can benefit from periodic nasal irrigation because it helps clear mucus and reduces congestion, irrigates the nasal passages to clear out pollen and dander, and can reduce post nasal-drip that may irritate the throat. Nasal saline solution is sold over the counter in most drug stores and can also be made at home.

An at-home nasal saline solution can be made by combining ½ teaspoon of non-iodized salt with one cup of purified water and allowing it to reach room temperature covered. A solution prepared at home should never be used for anything other than nasal irrigation. If you are not sure how to safely rinse nasal passages, ask for directions from a doctor or pharmacist.