Saline solution is a solution of salt (sodium chloride) in water. While it’s commercially available, saline solution is easy to make yourself, using nothing more complicated than salt and water.
Use the Right Salt and Water
If you’re making saline solution to soak sore muscles or as a mouth rinse, you don’t have to be as selective regarding the purity of the salt and water you use. However, for cleaning a wound, maintaining laboratory animals, or rinsing contact lenses, it’s important to use high-purity ingredients and maintain aseptic (sterile) conditions.
Salt: Salt from a grocery store is fine, but it’s best to select non-iodized salt. Rock salt or sea salt contain additional compounds, besides sodium chloride, so they are not suitable for some uses.
Water: For some purposes, ordinary tap water is fine. However, it’s generally best to use water that has been purified using distillation or reverse osmosis.
Uses of Saline Solution
Although you might not expect it, dissolving salt in water changes its pH, making it acidic. The combination of the low pH and the high salt content makes saline an excellent disinfectant and oral rinse. When saline is prepared to isotonic concentration (i.e., the same salinity as body fluids), it is used as a surgical rinse and for lab work. Isotonic (physiological) saline causes less tissue damage than pure water. Saline solution may also be used to hydrate contact lenses. Freshly prepared homemade saline may be used for this purpose, in a pinch, but commercial preparations are recommended for contacts because they contain added chemicals that aid with disinfection and prolong shelf life.
How to Prepare Saline Solution
To soak unbroken skin, simply dissolve salt into very warm water. For this purpose, it’s fine to use tap water and any form of salt. Epsom salt (magnesium sulfate) is another salt that’s good to use.
For an oral rinse, dissolve non-iodized salt into very warm water. You can add a bit of baking soda or sodium bicarbonate.
For sterile, isotonic saline solution, dissolve 9 grams of non-iodized salt per liter of purified water or 1 teaspoon of salt per cup (8 fluid ounces) of water. Sterilize the solution by bringing it to a boil. Place a lid over the container when you turn off the heat to help keep out pathogens.
Sterile solution may be dispensed into sterile containers. Containers may be sterilized either by boiling them or by treating them with a suitable disinfectant. Label the container with the date and discard it if the solution is not used within a few days. Sterile, isotonic saline is suitable for rinsing wounds, treating fresh piercings, and for lab work.
References
- British National Formulary : BNF 69 (69 ed.). British Medical Association. 2015. pp. 683, 770. ISBN 9780857111562.
- Dittman, Gerald L. (February 16, 1977). “Calculation of Brine Properties“. Lawrence Livermore Laboratories. Livermore CA.
- Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. pp. 8–71, 8–116. ISBN 0-8493-0486-5.
- Pestana, Carlos (2000). Fluids and Electrolytes in the Surgical Patient. Lippincott Williams & Wilkins. p. 11. ISBN 9780781724258.
- Reddi, BA (2013). “Why is saline so acidic (and does it really matter?)”. International journal of medical sciences. 10 (6): 747–50. doi:10.7150/ijms.5868