Gargling with salt water is one of the old cold remedies that really helps treat a throat infection. So, how does gargling salt water help a sore throat? Well, there are two theories, each drawing from the same chemical theory of osmosis. The basic premise of osmosis is that water will move through a thin membrane, or skin, into another fluid of a higher concentration. This movement happens until the concentration inside the membrane is the same of that outside of it. The two theories on how gargling salt water helps a sore throat deals with osmosis in two very different ways.
Osmosis and Bacteria
The first school of thought regarding gargling with salt water follows the premise that most cases of sore throat are caused by bacteria. If you can remember from middle school biology, bacteria are one-celled organisms that group together to cause some very hideous symptoms in humans. Although bacteria are sometimes helpful to the human body, they are the catalyst behind several human illnesses, including sore throats. These single-celled organisms are full of fluid, and the saltwater is highly concentrated, more so than the fluid inside the bacteria.
When gargling, the saltwater stays in contact with the bacteria long enough to start osmosis. The fluid inside the bacteria moves across its membrane into the briny salt water, until the concentration of fluid inside the bacteria is the same as outside. Of course, this leaves the bacteria sufficiently lacking in the fluid it needs to operate. Thus, the saltwater works to stop the throat infection by dehydrating the bacteria.
Osmosis and Edema
Others believe that eliminating the bacteria with cold remedies like gargling with salt water, does nothing to relieve the swelling or oedema in the throat. According to this school of thought, the immediate relief from gargling salt water wouldn't come from killing the bacteria, but rather from eliminating the swelling. This theory uses osmosis the same way, however. It holds that while you are gargling, the salt water is in contact with the swollen throat. The fluid in the throat tissue causing the oedema or swelling is of a lower concentration than the briny salt water. T
herefore, the oedema fluid passes through the throat tissue into the brine until the fluid on both sides of that tissue is of the same concentration. Since the soreness is caused by the oedema and the oedema by the fluid build-up, eliminating the fluid eliminates the sore throat.
Does Salt Water Help a Sore Throat?
Both theories hold that gargling salt water one time is not enough to get maximum benefit. The process must be repeated and accompanied by other measures, such as the proper vitamin regimen and plenty of fluids. Another commonality is the composition of the brine. It must contain a high concentration of salt. You can gauge this by adding first a teaspoon of salt to the water and stirring until it dissolves. Taste it. Repeat until the water is salty to taste.
Remember to use warm water which will soothe your throat and gargle salt water a few times a day when you have a throat infection.